Fundamentals of HVAC/R

What is an LMS?

2012-02-11T06:07:00.000-08:00

A Learning Management System, or LMS, is a software approach to organizing and administering a course. Typically, learning management systems are used for online classes. An LMS is basically a web site construction kit that is targeted to education. The LMS allows teachers to manage rosters, design the flow of the course, deliver online content, administer assessments, and calculate grades. For most of us, trying to do just one of these on our own without would be a daunting task. The learning management system makes it possible for teachers to design and administer structured and effective online courses that would probably not be possible without the tools provided by a good learning LMS. Of course web content and technology can be used in traditional classrooms as well as online. The learning management system just makes this far easier. This is not to suggest that today you acquire LMS software and next week you are launching your own Cyber University. There is still quite a learning curve. Because these systems typically can do a lot of things, there is a lot to learn. Although there are many similarities in the different systems, each really has it’s own unique interface and set of tools that you must learn. Compared to the work in a traditional lecture course, I would say there is more work on the front end and less on the back end. This is especially true the first time you offer a course using an LMS. However, the beauty of technology is that once you have that course built, saving, maintaining, and reusing it is relatively easy.

There are many choices for LMS software includng the Open Source program Moodle, commercially hosted systems such as BlackBoard, or systems managed by publishers such as MyHVACLab. Moodle is free, but like all open source freeware, there is a cost, it is just not money. There is good documentation on how things work, but you pretty much have to figure it out for yourself because there is no paid support. There is an active community where you can often get questions answered, but there is no “tech support.” If you are a Linux fan and use Open Office for your general day to day office software, you would probably be very comfortable using Moodle.

BlackBoard is probably the largest and most well known commercially hosted LMS. Many publishers provide Blackboard course “cartridges” to accompany their texts. A cartridge is a collection of resource files, such as pictures, presentations, or test banks that can be loaded into Blackboard to make developing a course easier. Typically a school or school system pays Blackboard to host their courses, allowing teachers to develop courses using their system. Blackboard takes care of the hosting and provides technical support. A downside to this type of hosting is that you can lose all your courses if you decide to go with another system. Our Technical College System switched from Blackboard to Angel a few years back, and the change was abrupt and traumatic.

A third option is an LMS hosted by a publisher such as Pearson. Pearson has been offering online courseware for many years. One of the most well-known is MyMathLab which is used by thousands of schools all over the country. Publisher managed learning management systems are usually designed to support a particular text, so integration with the text is very easy. A big advantage of the publisher systems is that they deliver a finished product, ready to use. Moodle and Blackboard deliver a platform on which to build, but you still need to build the courses. MyHVACLab accompanies Fundamentals of HVACR. It is a complete course including e-book, interactive activities, and assessments all organized around the structure of the book. You can still make the course your own by editing, rearranging, adding, or deleting; but you start out with a complete course right out of the box. Also, you don't have to worry about your school system's contract expiring and losing all your classes. MyHVACLab does not cost the school anything to use. Instead, students pay a modest access fee. When bundled with the book, the cost is usually only $!5 - $20 more than the cost of a book by itself.

This post is a little long, but we have just scratched the surface. There is no question that using an LMS requires a good deal of effort, but I believe if you make the effort you will find it very rewarding.

Exploding Refrigeration Containers

2012-01-29T16:30:00.000-08:00

Prices for HCFC 22 are finally rising to the levels that were expected this past summer. With the rise in refrigerant price will come increased interest in replacement refrigerants. For your safety as well as your customers safety, make sure you know where your refrigerant comes from. Avoid bargains from people you don’t know. This is not just about obeying the law, it is also about safety. Several container refrigeration systems have exploded after being charged with counterfeit R-134A. Container refrigeration is more difficult to patrol because the containers travel all over the world. Three articles discussing the accidents involving the mystery replacement refrigerant can found World Cargo News, ACHR News, Huffington Post.

Although flammable refrigerant s can be used safely, systems using flammable refrigerant use components designed for that use. Systems designed for flammable refrigerant also have limits on the amount of charge in the system and carry warnings regarding the flammability of their refrigerant. To stay safe, only use SNAP approved replacement refrigerants and only purchase refrigerant through the normal supply chain.

AHR Expo 2012

2012-01-23T17:41:00.000-08:00

The AHR 2012 Expo is happening this week at the McCormick Place in Chicago. It runs Monday January 23 – Wednesday January 25. The AHR Expo is the granddaddy of all air conditioning industry shows. It is co-sponsored by two of the HAVC/R industry heavy hitters: ASHRAE and AHRI. This is truly a world class show with people and companies from all over the globe. My experience has been that it is really impossible to look at all the exhibits in a day because there is so much to see. If you are located anywhere close to Chicago and can find a day to visit the expo, it is well worth your time. Instructors and students can get so much free literature that it will take you hours just to read it all. There are many free seminars every day for discussion of new technologies and products. The AHR Expo is usually where HVAC/R companies roll out their latest and greatest, so it is a perfect place to see where the industry is heading. Perhaps most useful to instructors are the contacts you can make with OEM suppliers, manufacturers, wholesalers, and industry technical gurus of all stripes. You may not be able to swing by this year, but you can still see who is there and even take a look at some of their info via a virtual show feature on the AHR Epo web site. On the main page of their site are photos and tweets. At the top of the main page is an Exhibitors menu. One selection in the middle of the list is AHR Expo TV. Videos of different vendors booths are available to see the the booth without traveling to Chicago. Also, check out the exhibitors list. There are so many, that it is organized as a search. When you get to a specific vendor, their contact information is listed. This is a great tool for searching who's who in the HVACR field. So if you can't swing by the Windy City, take a virtual tour.

Transcritical Refrigeration

2012-01-15T13:03:00.000-08:00

There has been a lot of work in the last decade on using carbon dioxide as a refrigerant. It is inexpensive, non-flammable, non-toxic, compatible with most materials, relatively friendly to the environment compared to fluorinated refrigerants, and has the potential to be quite efficient. There is one large obstacle to using CO² as a refrigerant: its critical point. The critical point is the highest pressure and temperature where the refrigerant can still condense. At and above the critical point there is no distinction between gas and liquid, so no condensation or evaporation can take place. The very top of the hump in a refrigerant enthalpy diagram is the critical point. A normal refrigeration system is a subcritical system because all the system components operate at pressures and temperatures below the critical point. (See Unit 18 in Fundamentals ofHVACR for more details on refrigeration enthalpy diagrams.) The problem is that critical temperature for CO²is 88°F. The condenser saturation temperature for most refrigeration systems is above 88°F, especially for air cooled systems that must use hot outdoor air for cooling the condenser. This prevents the use of CO² in a “normal” refrigeration system which uses an evaporator to absorb heat and a condenser to reject heat.

One application of CO² refrigerant is called a transcritical system because part of the system operates above the critical point and part of the system operates below the critical point. Subcritical, supercritical, and transcritical all describe a refrigeration system’s operating pressures and temperatures relative to the critical point of the refrigerant in the system. A typical “normal” refrigeration system is a subcritical system because everything happens below the critical point. In a supercritical system, all the components operate at pressures and temperatures above the critical point. A supercritical system operates on gas compression and expansion with no change of state. All heat transfer occurs by the gas changing temperature. A transcritical system operates both above and below the critical point. Heat is absorbed in an evaporator where liquid evaporates to a gas, but heat rejection takes place above the critical point, so there is no condensation in what normally would be considered the condenser. The refrigerant does not condense back to a liquid until after the pressure is reduced. For more details on transcritical refrigeration systems, see Unit 85 Commercial Refrigeration Systems in Fundamentals of HVACR, 2nd edition.

The Christmas Gift

2011-12-24T06:26:00.000-08:00

A few years ago Mike would have been annoyed to be asked to work on Christmas day. After more than a year without a steady job, he is pleased to work this Christmas. Mike worked hauling sand and gravel for construction and there simply has not been much demand for those services. Last Christmas he was concerned about how he would provide for his family. This Christmas he is working at a local hospital doing systems maintenance, and he is happy to do it. Not only does he receive a steady paycheck, but he also receives decent job benefits, including health insurance. In short, he can provide for his family. Further, he is performing a valuable service that he takes pride in. Nobody is giving him anything, he has earned it. His employers are pleased to have a skilled worker at a time when truly skilled workers are hard to come by. There are a lot of people wanting jobs, but not so many offering the skills needed for an HVACR technician. The people in the hospital have a place to go to heal thanks to the workers like Mike who work through the holidays insuring everything in the hospital keeps running. So what is the difference between last Christmas when he did not know how he would support his family and this Christmas when his services are needed? Education. Mike enrolled in Air Conditioning Technology at Athens Technical College. He could not have afforded the cost of school entirely on his own, even though our costs are quite low compared to other colleges. He received help from government programs promoting technical education. In essence, we the people made an investment in Mike. So what did we receive? The government will get their money back in one to two years of taxes. Afterwards, the taxes on his income can be used for years to come. Mike’s family will not need any government support because he is supporting his family. The hospital receives a skilled and loyal employee to help provide a place for the community to heal. Mike practices a skilled trade in a profession he truly enjoys. We received a great deal. Merry Christmas Mike.

EPA Approves Flammable Hydrocarbon Refrigerant Use

2011-12-18T15:01:00.000-08:00

On December 14, EPA issued a final ruling approving 3 flammable hydrocarbon refrigerants for use in small domestic and commercial refrigeration appliances. The three hydrocarbon refrigerants approved as acceptable substitutes are propane, isobutane, and R-441A. Hydrocarbons will now be allowed in domestic household refrigerators, freezers and window air-conditioners in the USA. Isobutane R-600a and a proprietary blend R-441A. are approved for use in household refrigerators, freezers, and combination refrigerators and freezers. R-441A is a patented blend of ethane, propane, butane and isobutene. Both its ozone depletion potential and its global warming potential are 0. It is also considerably more energy efficient than R-134a. Flammable refrigerants have been used for many years in small refrigeration appliances in other countries, including China. One of the most likely immediate effects of this ruling is to allow importation of refrigeration appliances charged with hydrocarbon refrigerant. Propane is approved for use in stand-alone retail food refrigerators and freezers. There are restrictions on the use of these refrigerants due to their high flammability.

1. They me only be used in new equipment specifically designed for their use.

2. the appliances must meet the UL Standard 250 for household refrigeration or UL Standard 471 for retail food refrigeration.

3. The quantity of refrigerant in a refrigerator or freezer shall not exceed 57 grams (2.0 ounces) in the household refrigeration end-use or 150 grams or (5.3 ounces) in the retail food refrigeration end-use.

4. The appliances must be marked with designated flammability warnings.

5. The piping and service ports must be painted red with a specific red color : pantone 185.

6. The service aperture must differ from regular non-flammable refrigerant service apertures.

7. These refrigerants may not be sold for use as a refrigerant in containers designed to contain less than 5 pounds (2.3 kg) of refrigerant.

To read more check out one of the following links:
Draft of Final Ruling
Supermarket News Article
ACR News Article

Cold Weather Heat Pump Charging

2011-11-26T16:52:00.000-08:00

Checking the refrigerant charge of a heat pump in cold weather can be confusing for many technicians, at least partly due to the many different methods recommended by different manufacturers. Although there are many methods, most are described as heating performance charts or heating cycle check charts. A check chart is just that, a chart for CHECKING the charge during the heating cycle. It is not intended to be used for actually ADDING refrigerant. Why? Lower outdoor temperatures cause a lower evaporator temperature and pressure. Lowering the evaporator pressure increases the compression ratio, so the compressor capacity is reduced. Less refrigerant is being circulated in the refrigerant system because of the diminished compressor capacity at low outside ambient temperatures. The refrigerant that is not being circulated must sit somewhere, usually in the accumulator. For this reason, a charge which is adequate to maintain correct pressures and temperatures at 25°F may not be adequate at 35°F. How? Suppose that the unit was undercharged according to the check chart. If you add just enough refrigerant to bring it up to the required pressures, you have only added enough refrigerant for correct operation at that one condition. When the outside temperature rises, the unit will be capable of pumping more refrigerant. However, since you didn't add any extra refrigerant, there won't be any more to pump. The system will be undercharged. Just adding a little extra is not a great ida either because you really have no way to determine how much extra to add. This is why manufacturers say that the check chart cannot be used to CHARGE the system, only to check its operation. If the system is undercharged, the recommendation from many manufacturers is to recover the refrigerant in the unit and weigh in a total system charge according to the manufacturer's instructions.

Thanksgiving 2011

2011-11-20T17:26:00.000-08:00

Once again, Thanksgiving is here and I have so much to be thankful for its hard to know where to start. My family is doing well, my children are achieving and prospering, and my HVACR program has so many students that we have had to work really hard to meet their needs. All the Air Conditioning instructors at Athens Tech have really stepped up their game. Dennis Payton, Coleman Simmons, Gary Manley, Jack Parsons, Gene Smith, Bill Ely, and Kenneth Harris have done a stellar job this semester. I know that our students are fortunate to have the dedicated and talented instructors that I am fortunate to work with. We are coming to the end of our first semester since our system switched from quarters to semesters, and the transition has been smoother than expected.

I know that there are still far too many people without work and that the hard times have boosted our enrollment as people look to invest in their future. Our job as teachers is to insure that they have made a wise investment. We are preparing our students to answer the call when opportunity knocks. How many stories have you heard about someone being successful because they were in the right place at the right time? There is another part of their success that often goes unmentioned: they were prepared to answer when opportunity knocked. That is what students all across America are doing today – preparing for opportunities to come. Schools are bursting at the seams. We are planting the seeds of tomorrow’s success. I truly believe that a better educated, better trained pool of workers will propel our country into a time of prosperity in the coming years. Times will get better, opportunity will knock, and our students will be thankful that they were prepared to answer the call.

80% Furnace versus 90% Furnace

2011-11-12T15:25:00.000-08:00

This week I would like to follow up on the 80% versus 90% debate. The primary argument for installing an 80% furnace is the lower cost of the equipment. However, a colleague of mine suggested that there is really not much difference in the installed cost because of the difference in the cost of the vent pipe. Standard B-vent is far more expensive than the PVC that is used in 90% furnaces. If the furnace is in a crawl space or basement, the 80% furnace must be vented through a chase or closet while the 90% PVC vent can usually be run sideways out through the wall. This also saves on labor. His argument is that the extra cost associated with installing a Category I furnace vent eats up the difference in cost between an 80% furnace and a 90% furnace.

For a changeout, the math will favor an 80% furnace because there is already an existing vent. However, check to see if the vent is adequate. You may need to make improvements to the existing vent for the furnace to operate safely. Often, a fan assisted replacement furnace will use a smaller vent than the older natural draft furnace it is replacing. It is possible for the old vent system to be too big, causing condensation inside the vent which leads to rapid vent corrosion. Many older natural draft furnaces are vented into masonry chimneys, a practice that is usually discouraged when applying fan assisted furnaces. Several manufacturers require a metal flue liner for the masonry chimney, eating up most of the cost savings. Another common practice in older furnaces is the use of single wall vent connector. You really don’t want to connect a new fan assisted furnace in a cold location to a single wall vent connector, especially not an old one. I have seen single wall vent connectors rust through and fall on the ground in less than a year after installation of a new fan assisted Category I furnace. Again, replacing the old vent connector eats up some of your savings.

It is true that there is still quite a cost difference between an 80% single stage furnace with a PSC blower and standard controls versus a 90% two stage furnace with an ECM motor and communicating controls, but the cost difference has more to do with the improved blower and controls. For a true cost comparison, both furnaces should have similar blowers, staging, and control systems.

Appliance Energy Efficiency Standards

2011-11-05T07:21:00.000-07:00

The Federal Department of Energy, DOE, has issued a direct final ruling making on furnace and air conditioner efficiency. The regional efficiency standards ruling went into effect October 25. The country is broken into three regions: North, Southeast, and Southwest regions. A map can be seen at MAP. Read more about the ruling at RULING.

In a nutshell: in the Northern region furnace efficiency will increase while heat pump and air conditioning efficiency will remain the same; in the Southeastern and Southwestern regions furnace efficiency will remain the same while heat pump and air conditioning efficiency will increase.

The table below listing the changes comes directly from the final ruling.

Table I.1 Amended Energy Conservation Standards for Furnace, Central Air Conditioner, and Heat Pump Energy Efficiency

Residential Furnaces*
Product Class	National Standards		Northern Region Standards**
Non-weatherized gas	AFUE = 80%		AFUE = 90%
Mobile home gas	AFUE = 80%		AFUE = 90%
Non-weatherized oil-fired	AFUE = 83%		AFUE = 83%
Weatherized gas	AFUE = 81%		AFUE = 81%
Mobile home oil-fired‡‡	AFUE = 75%		AFUE = 75%
Weatherized oil-fired‡‡	AFUE = 78%		AFUE = 78%
Electric‡‡	AFUE = 78%		AFUE = 78%
Central Air Conditioners and Heat Pumps†
Product Class	National Standards	Southeastern Region†† Standards		Southwestern Region‡ Standards
Split-system air conditioners	SEER = 13	SEER = 14		SEER = 14 EER = 12.2 (for units with a rated cooling capacity less than 45,000 Btu/h) EER = 11.7 (for units with a rated cooling capacity equal to or greater than 45,000 Btu/h)
Split-system heat pumps	SEER = 14 HSPF = 8.2	SEER = 14 HSPF = 8.2		SEER = 14 HSPF = 8.2
Single-package air conditioners‡‡	SEER = 14	SEER = 14		SEER = 14 EER = 11.0
Single-package heat pumps	SEER = 14 HSPF = 8.0	SEER = 14 HSPF = 8.0		SEER = 14 HSPF = 8.0
Small-duct, high-velocity systems	SEER = 13 HSPF = 7.7	SEER = 13 HSPF = 7.7		SEER = 13 HSPF = 7.7
Space-constrained products – air conditioners‡‡	SEER = 12	SEER = 12		SEER = 12
Space-constrained products – heat pumps‡‡	SEER = 12 HSPF = 7.4	SEER = 12 HSPF = 7.4		SEER = 12 HSPF = 7.4

The increased standards will be phased in over a period of years. Compliance with the standards in the direct final rule will be required on May 1, 2013 for non-weatherized furnaces and on January 1, 2015 for weatherized furnaces and central air conditioners and heat pumps. Industry reaction has been split. AHRI helped to develop the standards and supports them. They want to avoid the confusion and cost that was associated with the 13 SEER efficiency change that gave the industry very little time to prepare. AHRI also points to the Canadian experience when they mandated 90% . Their sister organization, HRAI, has stated that there were very few problems with Canada’s implementation of 90% standards. Read the AHRI position at LETTER.

ACCA opposes the standards, especially the 90% furnace mandate, concerned that the extra cost will drive customers to illegal contractors, who feel no compulsion to follow the rules and will cheerfully install equipment that legitimate contractors are not allowed to offer. read ACCA position at ACCA.

HARDI also opposes the regional standards, citing the difficulty this will make for distributors who service two or more regions. Read HARDI position at HARDI. ACCA and HARDI also cite that there is currently no enforcement mechanism – no DOE police. Again, the problem is that contractors who don’t abide by the ruling achieve a competitive advantage over contractors who do. Regardless of how you feel about the ruling, this is now the law, and all of us in the HVACR industry should prepare ourselves. As far as the DOE police – be careful what you wish for!

Southface

2011-10-28T09:59:00.000-07:00

The Georgia State Consortium of Air Conditioning Instructors met on October 25 at Southface in Atlanta. Southface is a non-profit agency devoted to energy efficiency and sustainability in buildings and communities. In keeping with their ideals for sustainability, Southface does not allow bottled water, box lunches, or syrofoam cups in their facilities. I must admit, I was a little put out with all the rules. “Who do these people think they are?” But then I realized, they are actually practicing what they preach. They know who they are. A sponsor, Technical Training Aids, graciously provided our lunch wthin the confines of all the rules and it was great. We gathered there to hear about what Southface could offer and tour their facilities. They provided an overview of the new residential energy efficiency code and its application in Georgia. All new residential construction in Georgia is required to pass a blower door test and all new duct systems must pass a duct blaster test for tightness. Those two requirements are the big ones for HVACR contractors. Further, the people performing the test must be state certified to perform it. They get certified by taking a relatively short course that lasts less than a week and then passing a performance test. So at least in Georgia, installing tight duct systems is no longer an “add on” for the better homes, but a requirement. Although there will certainly be many contractors that will regard all this as a pain, at least one in Athens sees it as an opportunity. Anytime he sells a high efficiency changeout, he quotes a duct seal and wrap upgrade. A seal and wrap consists of removing the old duct insulation, sealing the duct, re-installing the old insulation, and insulating over the old insulation. The duct blaster is used to measure the duct leakage before and after the job to document the improvement. So even if you don’t work in Georgia, you might consider promoting duct sealing and insulation. If your competitors don’t do it, that is a way to differentiate yourself from them. Most homeowners can easily understand that leaky ducts cost them money. For many systems, sealing and insulating the ducts will improve system efficiency even more than installing a new high SEER system.

Making Connections

2011-10-23T19:04:00.000-07:00

Most curriculums, courses, and books are organized in a manner that resembles house construction. You lay the foundation and then add to that foundation as the material gets progressively more complex. The idea is to present the information in an orderly manner so that complex concepts can be understood. I believe that teachers have been using this general scheme for centuries. I also believe teachers have been frustrated for centuries when they discover that the reason the students don’t understand a higher level concept is that they really don’t make the transition from one conceptual level to another. The problem is that learning is really not too much like stacking bricks, but more like wiring circuits. We have to make connections to learn. It is not enough to present material in an orderly and logical fashion, we must also make connections between different pieces of information. Every chance you get, you need to show how one piece of information connects to another. The more mental connections the students make, the more likely they are to remember the information. Students sometimes ask how a particular piece of information is relevant. I believe what they are trying to say is that they don’t have anything to tie the information to. Random, disconnected facts are quite difficult to remember, and are not normally particularly useful. I like the Bing commercials where people blurt out a series of largely unrelated facts that are essentially useless because there is no logical connection between them. To students, I am sure our lectures can sometimes sound like one of these commercials. I try to connect ideas together – showing how one part of a system affects the others, how pressure is related to temperature, how resistance is related to current – you get the picture. Relationships and connections between ideas are just as important as a carefully crafted sequence of information. This is not to suggest that building a foundation of information is wrong, I would just use the analogy of a framework instead. A framework can allow connections in more than one direction. Understanding a few fundamental physics concepts provides a framework for understanding both refrigeration and electricity. Taken by itself, physics can be pretty dry stuff until you realize that it describes the world around us. Once the students start making connections linking concepts together the whole process can go viral – they start finding their own connections and asking their own questions. This can be a bit scary because you no longer have total control of the flow of information or questions, but it produces an energized, lively class. More importantly, when the students start connecting concepts they are taking an active role in their learning and are far more likely to retain the information.

Electric Heater Resistance - A Moving Target

2011-10-08T06:57:00.000-07:00

Most people know that inductive loads such as electric motors draw more current when they start. Did you know that this is also true of most electric strip heaters? The resistance of a conductor increases as its temperature increases. This is true of the nichrome wire used in electric heaters. The heater resistance is less when the heating coil is cold than after it heats up. The increase in resistance causes a decrease in current. In short: an electric heater draws a little more current when it starts than after it heats up. The difference for an electric strip heater is nothing like the huge surge that a motor has, but it is measurable. For incandescent light bulbs, the difference is huge because the temperature difference between hot and cold is much greater. An incandescent light is basically a heater that gets white hot and gives off light. Lights don’t work for Ohm’s Law experiments because their resistance hot is around 10 times as high as their resistance cold. Many years ago I tried having students do Ohm’s Law calculations with lights – it just does not work. The readings were so far off, that the results did not make sense. I tried to put the difference down to measurement error, but the readings were always similar. Screw in cone heaters work better, but if you put enough current through them for them to get red hot, their resistance will increase and your readings will still be a little off. At least they are in the ballpark. It is something of a catch 22. To measure resistance an ohm meter puts a small amount of voltage across a resistance and measures the current, and then determines the resistance based on the amount of current that flows through the resistance. The problem is that the resistance changes when different amounts of current flow through the same device, based on the temperature change of the device. Remember that the resistance is turning the electricity into heat, and the heat changes the resistance of the device. Fortunately, the relatively small difference we see in electric strip heaters does not create a substantial problem for us, but it does raise questions when trying to demonstrate Ohm’s Law. If you want to reduce the amount of error introduced by the temperature change, just work with lower voltages and current levels. Use a typical electric strip heater, but only put 50 volts through it. The current and voltage are still measureable and the results will be much closer to what Ohm’s Law predicts. I know there are probably many skeptics reading this, so I challenge you to prove it to yourself. Take a heater, a variable voltage source, a voltmeter, and an ammeter. Read the current draw of the heater at several voltages ranging from just enough voltage to get a current reading to the full voltage the heater can take. Then calculate the resistance using Ohm’s Law by dividing the measured current into the measured voltage. You should see that the resistance is higher at higher voltages because the heater is getting hotter. Have Fun!

Combustion Air - Don't Forget It!

2011-10-02T19:51:00.000-07:00

I am re-posting an article from October 2009 when I talked about combustion air because I believe failure to check the combustion air is a common error in performing gas furnace service.

The arrival of fall brings the start of gas and oil fired furnace seasonal checks. An easily overlooked problem with gas and oil furnaces is lack of combustion air. Although most technicians understand the necessity of adequate combustion air, it is easily overlooked if the technician views their job as servicing appliances rather than systems. Most school shops have no combustion air issues because they are typically great big leaky rooms. On the other hand, the newer homes your students are likely to see are typically very tight, requiring installers and service technicians to be conscious of the need for combustion air. I believe we should stress the consequences of inadequate combustion air. Most students understand that air is required for combustion and that new air must constantly be brought in to replace the air that was just used in the combustion process. They should understand that the carbon and hydrogen in the fuel are combining with the oxygen to make carbon dioxide and water, the normal products of complete combustion. You can then explain that if there is not enough oxygen, carbon monoxide and unburned carbon will start to form because there is not enough oxygen to complete the combustion process. As the combustion process continues in a room with inadequate combustion air, the pressure in the room becomes negative. This will reduce the effectiveness of the vent. In bad cases the combustion products can start to spill out of the vent. Now you have a scary situation: a combustion process producing carbon monoxide and combustion gasses spilling out into the room! I have heard of cases where smoke from fireplaces in newer homes comes rolling out into the room when the furnace comes on because the house simply does not have enough combustion air for both the fireplace and the furnace. Technicians should look for combustion air grills and vents when servicing furnaces. Typically there should be an opening or grille near the ceiling and another near the floor. If the grille opens directly to the outside the free area of the grille should be at least one square inch for every 4,000 Btuh of combined input rating. If the combustion air must travel through vertical ducts the ducts must also have a free area of at least one square inch for every 4,000 Btuh. If the air must travel through horizontal ducts, the grille and the ducts must be larger. They must have a free area of at least one square inch per 2,000 Btuh. Draft measurements and room pressurization measurements can tip off technicians to combustion air problems. Because a draft gauge measures the vent pressure relative to the room pressure, inadequate combustion air will cause the draft reading to decrease the longer the furnace operates. An absolute pressure reading of the room will show that the room pressure is decreasing as the furnace continues to operate without adequate combustion air. A quick test is to introduce more combustion air near the furnace by opening a window or door to the outside. If the draft increases when the window is opened and decreases again when it is closed, the room needs more combustion air. For more a more detailed discussion of combustion air check out Unit 37 Gas Fired Heating Systems, Unit 40 Gas Furnace Installation, Startup, Checkout and Operation, Unit 41 Troubleshooting Gas Furnaces, and Unit 44 Residential Oil Heating Installation in Fundamentalsof HVAC/R.

Budget Stretching Ideas

2011-09-23T06:22:00.001-07:00

Schools face a serious budget crunch these days created by expanding enrollment and shrinking resources. There are many small things that you can do to stretch your budget and still provide a reasonable level of training for your students. Refurbishing tools that have become shop worn rather than replacing them is one small possible savings. Tools that normally last for years in the field sometimes only last a few semesters in our lab due to the harsh treatment they sometimes receive as well as the constant use. The seals and depressors in hoses are one example. If you have refrigeration hoses that leak, often the leak is in the seal on the end. The seal in most hoses is a small rubber tube that slips into the end of a brass cup in the end of the hose. The core depressor is either held in place by the seal or screws down into it. Replacement seals and depressors are available for most brands of hoses. If the hoses you have are used for connecting to refrigerant cylinders, vacuum pumps, or recovery machines, there is really no reason to have the core depressor. Removing it will speed up all those operations by removing a restriction. A larger savings can come in the type of brazing rod you keep. While I prefer 15% silver, it is now over $100 a pound and we use several pounds a semester. I hate to have students braze any less because brazing is one of those skills that must be practiced. 0% copper-phos is just over $10 a pound and does the same job. No, not as easily, but I can buy a semester’s worth for less than one pound of the 15% silver. Another savings for many programs is to reduce the paper you hand out. I have always been fairly liberal with the handouts, believing that it is important to disseminate information. I still believe that, but I have modified the way I share information. I started by writing a book that had more of what I wanted in it. But there will always be new information you run across that you want to share. Increasingly, I do this electronically by sharing web addresses. Finaly, let the supply houses and contractors in your area know you need help. They can keep their eye out for opportunities to help you. This past year we have received several donations from contractors and supply houses of “stale” stock or equipment with issues. They receive a tax deduction and we receive equipment. A unit with an issue may be a problem for a contractor, but it is an opportunity for my students . We have received two new packaged heat pumps this past year that had leaks on the pilot tubes of the reversing valves. Students patched the leaks and the valves worked. Now we have two new packaged heat pumps.

Picture Perfect

2011-09-16T15:32:00.000-07:00

Several years ago when I was a student in one of myeducation classes at the University of Georgia, the instructor asked us whatshould have been a fairly simple question for a group of teachers: “How do youknow when learning has taken place?” I don’t remember my response, but I doremember that the question really brought me up short because it was not askinghow do you know when the student has mastered a particular knowledge or skill,but how do you know when they have learned something? Well it is a little late,but I received a great answer today: Learning has taken place when the student requests that theirpicture be taken with their project. We have a flaring project in whichstudents make an assembly of 1/4”, 3/8”, 1/2”, and 5/8” copper all connectedtogether by flare fittings. After it is done, it is tested for leaks with 100psig of nitrogen and soap bubbles. After completing their project, one studentwanted a picture. Then they requested I take a picture of them holding the project.The student’s broad smile gave me the answer to the question posed to me manyyears ago. Learning has taken place when the student can enjoy the pride ofachievement with tangible proof of their accomplishment. In technical educationwe have a huge advantage of being able to actually produce. The students’ prideis not based on my judgment, it is based on holding something they made thatthey could not make yesterday. Some people consider trade skills and knowledgeas inferior to pursuits that are purely academic. However, I feel that a strongcase can be made that technical skills are actually a higher form of learning because the students must actually perform. Reality is the harshest judge of all – either it worksor it doesn’t. Our students must not only understand the theory, they must alsoapply it and pass the performance test. So if I had to list a learning sequencetoday, it would be: you study, you struggle, you sweat, you smile!

Brain Building

2011-09-10T08:49:00.000-07:00

Your brain is an essential component for all forms ofeducation. One obvious way to improve learning results is to improve studentsbrain capacity. Some forms of teaching are better than others at building braincapacity. I have noticed that frequently, “smart” students actually work harderthan “dumb” students. I believe that their study habits and the way theyapproach life in general not only builds their knowledge, it also builds theirbrain capacity. Just as hockey players skate and football players run toimprove their ability to perform the fundamental movements of their sport,students should exercise their brains to improve their ability to learn. Sowhat types of things build brain capacity? One proven way to build your brainis by learning to play a musical instrument. Playing an instrument uses bothhalves of your brain simultaneously, requiring better communication to bedeveloped between the right and left hemispheres. A few years ago at my son’sband concert, I realized that the trumpet section was also three fourths of theschools award winning math counts team. Playing an instrument is both incrediblydifficult and incredibly rewarding. Looking into this a little, I learned that Einsteinplayed the violin. His brain was perhaps one of the most studied in history. Hehad grown an extra lump on the right side of his brain, a feature found inautopsies of other proficient violin players. Einstein had to expand his braincapacity to play the violin! Of course it is possible that playing music doesnot make you smart, but that smart people enjoy playing music. OK, so besidesbrain building there are some more obvious benefits. For one, you learn self-discipline.You simply cannot learn to play a musical instrument without the self-disciplinethat comes with practice. Then there is group disciple. The members of orchestrasand bands must learn to work together as a group to perform music. The groupobjectives can only be met by subjugating all their individual egos. As a parent,there are a few other benefits. After half-time we hand out drinks to bothbands. I am always impressed by how polite and truly thankful the band members are.They all say thank you and are gracious even if we have run out of cold drinksand are handing out warm water. When I look out over the gathering of the twobands I know I am seeing leaders in every imaginable field and I am positiveabout the future.

Looking for a Day On

2011-09-05T05:31:00.000-07:00

Aswe celebrate this Labor Day I am reminded of the many Americans who don’t wanta day off, they are looking for a day on. Your job provides you with more thanthe financial means to support yourself. For most of us, we are identified byour profession. One of the first things people ask when meeting is “what do youdo?” Having regular earned income also gives us a way to be more in control ofour destiny. With a predictable source of income, you can manage towardsimproving your lot in life. I truly believe all our political leaders want tohelp. We would all like for everyone seeking employment to find it. There havebeen many attempts by government at all levels to pass legislation that wouldstimulate the economy and create jobs. The problem is that it is very difficultto create truly new jobs, particularly in new and emerging technologies. Ibelieve we would have more success investing our time and money training peoplefor jobs that already exist, particularly in fields where industry growthexceeds the available workforce. HVACR is one such industry. Jobs are availablenow for skilled HVACR technicians, even with the construction industryoperating at historically low levels. Money spent in technical education preparesstudents for real jobs that we know exist, not jobs that we wished exist.Preparing people for a real job that pays real money makes them a contributingtaxpayer. In short, the government gets the money back. Some HVACR students willbe successful enough to start their own business. There are several in theAthens area who started as students at Athens Tech. One relatively smallbusiness with five employees can gross $500,000. That generates tax revenue of$75,000 at 15%. If those five employees are trained at Athens Tech, the cost oftheir training is less than one year’s tax revenue. Not all students will generatethat kind of return, but even a student earning $12 an hour will likely payback the cost of training in two years. For people who already have a jobin HVACR, education makes them more productive. Increased productivity means abetter bottom line for the government – more income to tax. It is not necessaryto start new programs with new administrative costs; there are already programsand institutions in place with proven track records of training workers forskilled trades. All we have to do is support them.

Variable Speed Motors

2011-08-27T17:06:00.000-07:00

Electronically commutated motors are widely described as variable speed motors. In truth, most blower motors used in air conditioning are variable speed, including shaded pole and PSC motors. Muliple tap shaded pole and PSC motors are designed specifically to vary their speed based on the tap that is powered. All induction motors vary their speed depending on the load. An increase in load will result in decreased motor speed. What makes ECM motors unique is their ability to vary their speed intelligently in response to the load. They are often used to vary motor speed to maintain constant airflow. To do this, the motors are programmed to match the performance of the blower on which they are mounted. When the airflow through the blower is restricted, the motor responds by speeding up enough to keep the blower CFM the same. In truth, a common PSC blower motor also speeds up when the air through the blower is restricted. However, it does not speed up enough to offset the loss of airflow caused by the restriction, so the airflow decreases. The PSC motor is just responding the way any induction motor does to a decreased load. On a blower with a PSC motor, an airflow restriction causes a decrease in airflow and in motor amp draw because it is not under as much load. A blower with a constant CFM electronically commutated motor will still move the same amount of air by increasing the speed enough to overcome the restriction. Because the motor is doing more work, the amp draw will increase. This is why good duct design and clean filters are important to ECM equipment. The blower motor on a new system with an ECM motor may actually draw a higher amp draw than the old PSC blower it replaced if it is connected to a restrictive duct system. The popular X13 motors by Genteq are constant torque ECM motors. They vary their speed to maintain a steady torque output. When the blower airflow is restricted, the X13 ramps up its speed to maintain the same torque output. This will usually not be enough to completely overcome the restriction, but it will not be producing less torque when the system needs more torque, as is the case with a PC blower. Airflow still drops off, but not as much as with a PSC blower motor. A few systems use an external pulse width modulated signal to the motor to create a feedback loop that maintains an external measured system condition, such as static pressure in a duct system.

NIOSH Safety Resources

2011-08-21T19:14:00.000-07:00

The National Institute for Occupational Safety and Health (NIOSH) is the federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness.

The NIOSH web site has many excellent safety resources that your students can view or download. The site is large, so finding what you are looking for can sometimes be difficult, but it is worth the effort. You can find many excellent publications in their directory of publications. Click on the “Directory of Publications and Products” link on the bottom left side of their main page. There is a search bar to enter subjects you want to research. These are all free to download or view. Smaller documents can make excellent class safety handouts. Larger documents are more like small text books. For example the Electrical Safety Student Manual is really a book in pdf form. It is really good. One word of caution - it shows graphic pictures of electrical burns and injuries, not cartoons. However, I find that after viewing the results of a severe electrical burn, students are far more likely to be careful in the lab.It is really too big to print and hand out, but it can be downloaded and shared as a pdf, allowing students to view it on a computer.Other publications available through the NIOSH site are

Electrical Safety Page

Protecting Worker from Heat Illness

Pocket Guide to chemical Hazards

NIOSH Safety Videos

Arc Flash Awareness Video

NIOSH Fact Sheets

Document Your Abilities

2011-08-13T08:07:00.000-07:00

It is common for people who work in the HVACR industry to have very little documentation showing their proficiency. Many have never been to any formal school, others started and did not finish. Although there are now many certified techs, there are more that are not certified. This does not necessarily mean that they cannot perform their jobs, but that they have not taken the time to document their abilities. Often, the explanation is “I have been doing HVACR for 15 years and that is worth more than any piece of paper.” I would be the last to suggest that experience does not count – it does. But without a diploma or certification, how does a prospective employer know what you can do? In a tight job market, credentials matter. Many places examine resumes first to determine whom they want to interview. With no credentials, your chance of even getting an interview is slim. If you are one of the many HVACR workers without credentials, my suggestion is that you make documenting your abilities a priority. Chances are, there is a school somewhere near you that teaches HVACR. I am not suggesting that you quit working to go to school. It is often possible to do both. If you do not have any professional certifications from NATE, RSES, or HVAC Excellence you should work on obtaining professional Certification. Yes, it can take some time to go to school or study for a professional certification exam, maybe even a matter of years. Rather than focus on the length of the road, concentrate on the destination. One or two years will pass whether or not you are doing anything to improve your position. The question is, at the end of the time, where will you be? Will you be graduating with a diploma that documents your ability and opens doors, or will you still be right where you are today?

Everybody Wins!

2011-07-30T07:43:00.000-07:00

This past week I had the pleasure of attending the Alabama Council of Air Conditioning and Refrigeration Educators, or ACARE. The meeting was held at the Alabama Power training center, in Verbena, Alabama. The training room was full with approximately 50 HVACR instructors attending. Not only were there people from Alabama, but also Georgia, Mississippi, and Arkansas. ACARE is a great example of what can be accomplished through cooperation between industry and educators. The meeting could not have happened without the help of Joel Own and Alabama Power, but the instructors are taking a very active role in making everything happen. Instructors set the program and invited the speakers. They put together an impressive Alabama Power discussing the COVER approach to troubleshooting, Harold Nelson from Mingledorff’s discussing compressor failures, a tech forum with manufacturer’s service reps, Jeff Marques of Air Engineers showing off the new Trane Hyperion air handler, Chris Mohalley of Genteq on ECM motors, and me showing MyHVACLab. Harold and Chris both came fully loaded with handouts including books, powerpoint presentations, and manufacturer’s specifications. The handouts were worth the trip! The instructors received training in the latest technologies and Alabama Power lightened their load in the future, both literally and figuratively. Encouraging the development of HVACR Training programs in their state will produce more capable HVACR technicians for the future of Alabama. This translates into fewer problems with systems and energy saving savings. The state of Alabama wins two ways – they save on both education and energy costs. Suppliers such as Mingledorff’s make more money on customers with educated technicians because they don’t have to spend as much money on tech support and warranty. The instructors also are able to learn from and help each other. In times of economic stress, it really makes sense to help each other as much as possible because everybody wins.

The Dark Side of Cell Phones

2011-07-22T15:52:00.000-07:00

Several months ago I wrote about the power of smart phones and how they can be used as a service tool. Properly used, phones can save mechanics a great deal of time. Unfortunately, they can also create problems. Many people that have grown up with cell phones are used to interacting with them continually, and that can be a problem in a service business. It is never appropriate to answer your phone when you are talking with a customer. It does not matter if it is voice or text, diverting your attention away from the person you are talking with is simply rude. If that person is a customer, the sin is compounded. Before you go to talk with a customer, turn your phone off. If you are accustomed to having your phone on all the time, it can be difficult to remember to turn it off before interacting with customers. I have been guilty myself. I once had my phone ring during a lecture that I was giving. I now try to get in the habit of checking my phone before I lecture. This advice also goes for talking with your coworkers and supervisors. A very talented student of mine lost his job because he was texting during a company meeting. The problem was not just that one incident, it was simply the straw that broke the camel’s back. Most places of business will expect your undivided attention when they are trying to talk to you. Similarly, customers expect your full attention. After all, they are actually paying for your attention. There can also be a safety aspect to phone use in a field that has many real physical dangers. You should focus your attention on whatever you are physically engaged in. Failure to do so can be downright dangerous. There are many articles on the web discussing cell phone etiquette. The Huffington Post has fifteen suggestions in an easy to digest list. But please finish your conversation with your boss before clicking on the link.

A Weighty Matter

2011-07-16T14:38:00.000-07:00

One day while I was setting up for a lab I noticed that two of my scales did not agree. What was worse, the discrepancy was significant, enough to make a system charge way off. One of the advantages of using electronic charging scales is the confidence that you have put the correct amount of refrigerant in the system. If you don’t trust your scale, you lose that advantage. I got a third scale to try and determine which was correct, but then I thought, how do I know ANY of these are right? Maybe I have two incorrect weights, not one. So I visited my friend Jimmy in the physics lab and asked for a weight. He gave me a 2 kilogram weight. I placed the 2 kilogram weight on the scale that I suspected of being off, and it weighed 2.3 kilograms. I then moved the weight to the scale that I thought was correct, and it read exactly 2 kilograms. This restored my confidence in my good scale and verified my suspicions about the bad scale. While this simple test does not replace NIST certification, it is a simple way to keep an eye on the accuracy of your digital scales and maintain your confidence in their readings. I do not believe most digital charging scales can be calibrated in the field, you have to send them into the manufacturer. But you can periodically check their accuracy. You may be wondering why I chose a 2 kilogram weight. Well, physics teachers work in SI, not inch pounds. Jimmy does not have any 2 pound weights. Nearly all science today Is done in SI units, not English units. If your school has a physics lab, you might want to pay them a visit. They have lots of cool toys. After all, air conditioning is really just applied physics.

Verify

2011-07-10T12:06:00.000-07:00

How do you know if your students have actually learned the material? Most teachers verify the results using tests. You check the student’s knowledge against a standard. If the student falls short, you provide some remediation and then test again until they meet the standard. In education, you would not assume that someone has mastered a subject simply because they read a book that had all the material in it or attended all the right lectures. You verify that they have learned the material using written tests, lab exercises, or some combination of both. How do you know that an air conditioning system performs efficiently as designed by the manufacturer? For many people this has involved using design using tools like ACCA Manual J and D, and installation using skilled personnel. These two steps are certainly important, but they can be compared to reading the book and attending the lecture. Without testing to verify your results, you really cannot be sure that the system is performing correctly. After installation, system performance should be verified by testing crucial system operating characteristics. The 2010 ACCA Quality Installation Standard provides a good format for keeping track of all aspects of a quality installation that need verification. Verification is becoming a very big deal in our industry. Increasingly, energy codes, utility rebate programs, and government programs such as Energy Star are insisting on performance verification. It is no longer enough to install a high SEER unit, you must now test and seal the ductwork and test system performance against manufacturer specifications. You can download the ACCA Quality installation Standard from their website https://www.acca.org/industry/quality/quality-installation

We the People

2011-07-02T06:44:00.000-07:00

Happy Birthday USA! We celebrate July 4^thas the start of our nation. More correctly, it was the official start of the rebellion with the Declaration of Independence. We would not be the United States of America until nine out of the 13 states had ratified the United States Constitution. The Constitution was signed on September 17, 1787. However, it stipulated that it had to be ratified by 9 of the 13 states before it would take effect. Some states were concerned that the Constitution did not specifically reserve powers not mentioned in the document for the states. The Bill of Rights was proposed as a solution. If these states would ratify the document, they were assured that the Bill of Rights would be quickly passed. On June 21, 1788, New Hampshire became the ninth state to ratify the document, and it was subsequently agreed that government under the U.S. Constitution would begin on March 4, 1789. On September 25, 1789, the first Congress of the United States adopted 12 amendments to the U.S. Constitution--the Bill of Rights--and sent them to the states for ratification. Ten of these amendments were ratified in 1791.

The point of the brief history lesson is that the whole process from inception to the start of the first congress was based on representation. The US Constitution starts with the phrase “We the people…” Not we the chosen, we the wealthy, we the powerful, or even we the elect, but we the people. Elected representatives wrote and signed the Declaration of Independence. Elected representatives wrote and signed the Constitution. Elected representatives in all 13 colonies eventually ratified the Constitution. And finally, elected representatives voted on the Bill of Rights. All were elected representatives from their respective colonies. The men that signed these documents put their lives and fortunes in peril. Had they been captured by the British, they would have been tried for treason and hanged. Had they lost the revolutionary war, they would have lost all.

My challenge to all of you is to learn more about your country. A good place to start is at the links in the article above. And during the next election, learn about the candidates and issues and vote. To remain we the people, we the people have to participate.

Locking Refrigerant Caps Now Code

2011-06-25T07:28:00.000-07:00

I want to point out a relatively new provision of the International Mechanical Code and the International Residential Code – a requirement for locking refrigerant caps. In the International Residential Code the provision reads “M1411.6 Locking access port caps. Refrigerant circuit access ports located outdoors shall be fitted with locking-type tamper-resistant caps.” Since the IRC has become so common across the country, there is a good likelihood that your area requires locking access port caps. If you are like me, that may come as a surprise. The primary reason for the requirement is to discourage people from releasing the refrigerant and huffing it to get a quick high. Before you all go out and start snorting refrigerant, let me first tell you what it does. Basically, it deprives you of oxygen and you feel lightheaded and dizzy as a result. That is all the high is - dizziness from oxygen deprivation. Since it deprives you of oxygen, too much for too long and you die. Since refrigerant is heavier than air, once you have filled your lungs with refrigerant, it is hard to get it to leave so you can replace it with air. I first heard of this way back in the ‘70s when people would do just about anything, including smoking bananas and sniffing refrigerant. I thought it had gone away with so many other crazy ideas of the 70’s. However, there is an alarming increase in the number of people sniffing refrigerant. The mother of a teenage boy who killed himself huffing refrigerant has founded an organization called UPROAR which works to prevent similar tragedies. So where can you get these caps? They are available at wholesalers and also online. You can read more about them at NOVENT, or AirTec. Here are a few links to different tragic stories where people died from inhaling refrigerant.

UPROAR - many stories on this site.

Coral Springs Florida

Dust Off

Inhalent.org

Are You Becoming Obsolete?

2011-06-16T14:54:00.000-07:00

There is certainly a lot of change taking place in HVACR! New refrigerants to replace old standards and even newer refrigerants to replace the new refrigerants. Variable capacity compressors, communicating control systems, and communicating thermostats that look like an I-pad. It is tempting to say, no thanks, I will just stick with my R-22 units with single speed compressors operated by contactors that are controlled by mercury bulb thermostats. And yes, many of those are still around. However, if you choose to specialize in only retro technology, you are choosing to become obsolete. Technology changes whether or not we want it to. If your job is to install and service air conditioning equipment, you need to be familiar with what is current, or eventually you will be out of a job. I remember many years ago a technician in a parts house declaring that he simply refused to work on heat pumps. He basically was saying it was too much bother to learn about them, so he would just keep working on natural draft gas furnaces and air conditioners. He would not be doing much today because most the systems in this area are heat pumps and the rest are induced draft furnaces. What he was comfortable with just does not exist anymore. As technology changes, we have to adapt. Studying is just part of a technician’s job. I read about what is going on in the HVACR field almost every day. There are so many resources now. My favorite is the RSES Journal, but I also really like the Air Conditioning Heating and Refrigeration News. I will even pick up a book on occasion. Yes, I realize that reading printed material is somewhat old school, but both publications also have on-line articles. And there are always blogs. If you prefer face to face, find a local RSES chapter. The point is we all have to be students to stay current. Otherwise, we become as obsolete as mercury bulb thermostats and natural draft furnaces.

Are You Working Hard?

2011-06-09T19:30:00.000-07:00

The summer heat is upon us. I truly hope you all are busy. Busy is good. It certainly beats not having anything to do. However, have you ever wondered how much of your business is tied to the way you do things? Although nobody can give you any more time, you often can use your time more efficiently, which has the same effect. Learning to use your tools more effectively is important in any field. One example in teaching is designing, giving, and correcting tests. I have had quarters where at the end of the quarter I would have a box that a case of 10 packs of printer paper comes in full of paper tests to grade. I emptied it out printing the tests, and then filled it again after the tests had been taken. I still give written finals, but all other tests are on line. Using the test database built into MyHVACLab, I can build a test quickly. Better, I don’t use any of my time or any class time taking the tests. Best, I don’t have to grade a huge box of tests every few weeks. Even if you want to write all your own questions, keeping them in a test database still makes sense. You don’t duplicate effort because you can re-use your own questions. Even for my written finals, I use the database to generate the test. Instead of using class time having my students take tests, I try to use the time going over tests that they have taken. Nothing sears a piece of information into your brain like learning you just missed it on the test. Tools can be the same way. You can keep on doing the same things in the same way even when there is a more efficient way to use the same tools you already use. I have met many people who did not know that the “extra” lines inside their gauges were saturation temperatures. Essentially, a PT chart built right on their gauges staring them in the face. Digital gauges take this to an entirely new level of accuracy and flexibility, but even analog gauges normally have a few of the most common refrigerants on them. Spending a little extra on truck stock can save a lot of time. If you have the parts you need on your truck, you can do two calls in the time it takes to diagnose the problem, go get the part, and then return to put it on. Whatever you work hardest at, spend a little time analyzing why you do what you do and asking if there is not a more efficient way. The time you spend will be saved many times over.

Ride All the Rides

2011-06-02T16:53:00.000-07:00

Summer is approaching quickly. Undoubtedly, many of you will spend some time at an amusement park, water park, or other recreational establishment. Many parks now have a single price for admission that lets you ride all the rides as many times as you like. After paying the price of admission, most folks try to ride as many rides as possible to get their money’s worth. I can remember planning out my day at Disney World so that I would make the most of my time. I can see many of you smiling because you have done the same thing and planned a manic day at a pricey amusement park so you would get your money’s worth. So here is my question. Why are we so intent on getting our money’s worth at an amusement park, but beg to be cheated in education? When you pay your tuition for the semester, you are paying to ride all the rides. Every lecture, lab, online assignment, and test is available for the price of admission. If you think tuition and fees are high, why would you not take full advantage of all that you paid for? Try reading the assignments more than once. It does not cost any more, and you get more out of the assignment. When you miss a lecture, lab, or assignment you are cheating yourself. Not only are you not taking advantage of the services you have paid for, but you are also limiting your earning potential later on. My brother Richard has a saying “work hard at school, or work harder all your life.” HVACR is a very performance based industry. If you can’t perform, you won’t last long. HVACR is also a very technical field. To excel, you need to understand the systems and how they operate. Sure, without a lot of training you can get a job holding the other end of heavy things or running to get tools for other people. But without training or education, you won’t advance much past that point. There are many ways to educate yourself, but the easiest and fastest is to go to school. Throw yourself into your studies. Attend all the lectures, read all the assignments, and do all the labs. Ride all the rides!

A Chance to Contribute

2011-05-26T18:27:00.000-07:00

Most of us have been guilty at one time or another of saying “they should …” Of course you may have a long wait if you are waiting for “they” to fix everything. My father used to encourage me to “be part of the solution, not part of the problem.” Usually I heard this if he felt I was engaged in compounding the problem rather than solving it. How many times have you wished your students were better prepared in basic subjects like Math

or English? Well now you have a chance to do something about it.

The National Assessment Governing Board, part of the U.S. Department of Education, is conducting research that will allow the National Assessment of Educational Progress (NAEP)—known as “the Nation’s Report Card”—to report on the academic preparation required of 12th graders to enter various job-training programs after they graduate from high school. As part of this effort, WestEd, an education-focused nonprofit organization, is conducting a study that will determine what academic knowledge and skills are required for students to be placed in job-training programs such as yours. For more information about this project, you may find the Governing Board’s press release at http://nagb.org/newsroom/release/release-100810preparedness.htm . For more information about the Nation’s Report Card, please visit the Governing Board’s website: http://www.nagb.org .

I am encouraged that someone in the U.S. Department of Education is interested in the trades, specifically the HVACR trade. Maybe they are finding out what we already know – teaching people to work is the real economic stimulus the country needs. If you would like to be part of the solution, contact Dr. Jennae Bulat at naep-jss@wested.org to learn more about the study. The study will take place during a 4-day workshop to be held June 28–July1, 2011, in St. Louis, Missouri. I cannot go because I will be in Alabama at the Alabama Council of Air Conditioning and Refrigeration Educators meeting, but I thought I could at least recruit a few of my friends. They can’t use all of us, but I would love for them to have so many well qualified HVACR educators from all over the country that they have a hard time deciding who to invite. I know that we are all ready to be part of the solution.

The Hunt

2011-05-19T21:10:00.000-07:00

I had a conversation with a local contractor today who told me some of the things that impressed him about different job candidates. I thought I would pass a few of his comments along in hopes that it might help some of you out pounding the pavement looking for a job. First and foremost, remember that employers hire you based on what you can do for them. They are not philanthropists. With that in mind, spend a little time thinking about what you have to offer an organization so you will be prepared to answer when asked. Try and learn something about the companies you apply to. If you get an interview, you definitely need to learn whatever you can about the company. If they advertise that their employees are NATE Certified, stress your qualifications. Even if you are not yet NATE Certified, graduating from a respected program or passing the ICE exam is a good step in the right direction. Tom (not his real name) is a successful local contractor. He told me a few things he pays attention to. One was persistence and follow through. If someone comes by just once, he figures they are not really interested. He is impressed by students who return a few days after completing an application to inquire. Appearance is huge. Another contractor told me that the way an applicant looks to him is how he assumes they will look to his customers. You need to be clean and neat. Tom told me he remembered one student’s shoes – how shiny they were. The second time he came, his shoes were just as shiny. He got the job. He showed persistence and was consistently neat and clean in appearance. Do not wear a shirt with a slogan, witty comment, or add. You can never know what the interviewer will read into it, but why take a chance on creating a bad impression? It is also important to be dressed appropriately. Don’t show up in a three piece suit to apply for a job as a service technician. They may assume you are afraid to get dirty. It also helps to know your stuff. A student recently applied for a job and they gave him a test. He told me he knew he did terrible and wished he had studied before going to the interview. Later when I inquired, the contractor told me they had never had anyone score as high as he did. He got the job. More contractors are administering their own in-house tests. Don’t be surprised if they ask you to take a test. If you have studied HVACR at school, tests are your best friend – they give you a competitive advantage. Last, you need to have an upbeat, positive, can-do attitude. Remember, people often hire people they can get along with. After all, they are going to be around you a lot. Do not put down your previous employer. What the interviewer hears is you are a whiner and complainer. Do not put down your school, fellow students, or the instructors. If you successfully convince the interviewer that the school you attended is bogus, then why should they be talking to you? Definitely do not offer any current political or religious inspiration. I had a student lose a job over a comment about Ronald Reagan. Tell your beer drinking buddies what an idiot the president is, not your employer. Finally, when preparing for applications and interviews, think about who you would hire, then be that person.

Keeping Cool While Working in the Heat

2011-05-14T08:04:00.000-07:00

When my students come in complaining about the weather I sometimes respond, yes, isn’t the weather nice today! After all, if the temperature was always pleasant we would have far less to do. Some students are surprised that they will be working in hot conditions. Even if you are working inside an air conditioned building, if you are there to fix the air conditioner, it probably is hot. Seriously, it is a fact that the temperatures we work in are often very hot. In the southeast, the high humidity adds to the temperature perceived by the body. This is because the evaporation of sweat is your body’s only effective cooling mechanism in high temperatures. These can be dangerous conditions to work in if you don’t take reasonable precautions. First, you need to keep yourself hydrated. Drink a lot. Many technicians keep a large igloo cooler of water or gatoraide on their truck so they will always have a ready supply. In general, you should avoid alcoholic beverages, they actually tend to dehydrate you. Of course, there is an obvious safety issue of working with power tools while consuming alcohol – not usually a good idea. Caffeinated drinks are also not recommended because caffeine is a diuretic. Kind of like taking three steps forward and two back. You have to consume more because your system keeps getting flushed out. Although you cannot avoid working in the heat, you can avoid prolonged work in excessively hot areas such as attics. If at all possible, plan attic work early in the morning or late in the evening. This not only protects the workers, it improves productivity. You just cannot get as much done in the extreme heat. I recall doing a change out in an attic on a 95°F, 80% rel humidity day. The roof had black shingles and there was no shade. It did not take long before we had consumed all the beverages the family had to offer, other than tap water. However, the water was really what we needed. We worked all day, if you counted our rest breaks. Towards the end of the day we were resting for longer periods of time than we were working. Our clothes were literally dripping wet. I have no doubt that we could have done the work in half the time in cooler temperatures. My partner and I were both young and in good physical condition (a long time ago for me). I think I would literally die if I tried to do the same thing today. There are two forms of illness associated with your body overheating: heat exhaustion and heat stroke. Heat exhaustion can be treated by resting, cooling off, and rehydrating. If heat exhaustion is not treated, it will lead to heat stroke. Heat stroke is a medical emergency that can be fatal. It has symptoms similar to a heat attack. Be careful in the heat. While working in the heat, if you feel faint or dizzy, nausea, rapid weak heartbeat, cramps, or headache, move to a cool place and drink some water to rehydrate.

Charing - Read the Fine Print!

2011-05-06T04:26:00.000-07:00

There is an old saying that “the devil is in the details.” That is certainly true of refrigerant charging. There are so many details to keep track of. Outdoor ambient temperature, indoor wet bulb temperature, evaporator airflow, condenser pressure, evaporator pressure, suction line temperature, liquid line temperature, superheat, subcooling and approach. I am sure I left a few off, but that list is long enough to make my point: there is simply a lot to keep track of. The confusion caused by trying to make sense of so many variables can cause some technicians to look at only one thing, often they look at only the suction pressure. This is like covering your ears so you won’t hear the thunder. It does not keep you from being struck by lightning. It is true that no manufacturer specifies all those things in their charging information. However, many of these details are assumed so that system performance can be judged by one or two key indicators. The problem is that even a manufacturer’s charging chart will not be accurate if the conditions you have do not meet the assumptions used with the chart. You must read the fine print. Most manufacturers disclose their assumptions somewhere on the chart or in their service manual. A commonly specified condition is that the evaporator airflow is 400 CFM per ton and the return air temperature is 80°F 50% relative humidity. In our shop we have a packaged unit with a very simple charging chart. It gives the suction and discharge pressure for five specific outdoor temperatures. However, it is assuming standard airflow across the evaporator and indoor conditions that meet AHRI rating conditions – 80°F dry bulb 50% relative humidity. It is seldom that warm in our shop, so the pressures are usually lower than those specified on the chart. In the field, it is common for the indoor temperature to be above the AHRI rating condition, that is why you are there in the first place. You can expect higher pressures as a result. Superheat charts that list only an outdoor temperature have a similar problem. They assume an indoor temperature and humidity level. Even charts that specify an indoor wet bulb and an outdoor temperature are still assuming standard airflow across the evaporator coil. For that matter, all charging charts are assuming both coils are clean, that you have good airflow across both coils, and that all the refrigeration components are performing correctly. If any of these are not right, no charging chart will work. You should make a habit of checking airflow, air filter, and condenser cleanliness on every call. Then read the fine print to check any specified conditions used with that chart.

Saturation Temperatures

2011-04-30T05:29:00.000-07:00

One of the great things about writing this blog has been the friendships I have made with other folks involved in HVACR education. People write and share their ideas, or just send me a thumbs up on something I have said that they agree with or appreciate. They also let me know when I have overlooked something or suggest changes for the book. Believe me, David and I work very hard trying to make Fundamentals of HVACR a valuable resource to help you teach. We really do appreciate all the comments and ideas. This week I wanted to pass along an idea from Thomas Bush at South Florida Community College.

Thomas writes:

“This past year I’ve found myself referring almost exclusively to saturation temps on both the high and low side, rather than pressures, when working with the students in the lab. That’s really the important reading, whether you’re measuring superheat, subcooling, or even just ball-parking and older system. All of our gauges have 22 and 410a PT charts built in. We have dedicated sets for 134a. Seems like talking saturation temps takes the whole 22/410a question out of the equation. A 40° evap temp is a 40° evap temp no matter what refrigerant you’re using.”

I really like this idea. It reinforces why particular pressures are important. Eventually, the students/techs will get used to seeing 120 - 135 psig suction pressures on R410 systems, but they will know where the pressures came from. The pressure reading will not just be a random number. I believe emphasizing the saturation temperatures can also reinforce why we have a high side and a low side in the first place. With all the new refrigerants coming out, it is especially important that technicians understand why they are looking at a particular pressure. If you know the saturation temperature you are looking for, then a PT chart is all you need to find the pressure for a brand new refrigerant you have never worked with before. If you are fortunate enough to have one of the new digital gauge sets that can hold 40 different refrigerants, you may already have the PT chart built into your gauges. Many of these automatically display the saturation temperature as well as the pressure. Thanks to Thomas Bush for sharing his idea. I am sure the folks down in South Florida will have plenty of time to practice it soon. If anyone else would like to share a tip or successful idea, please don’t be shy!

How much refrigerant does it take to make the fan blow harder?

2011-04-21T18:26:00.000-07:00

Have you ever noticed that right after you buy a car you seem to see that particular model everywhere? Similarly, once you solve a problem, every problem you see seems to be another iteration of that same problem. My theory is that we are programmed to repeat our successes. The brain says “that worked before, lets do that again!” We are all occasionally tempted by the same quick fix demon that whispers in our ear “this worked the last time!” The temptation is just to repeat our latest success without really looking carefully at the actual problem before us. We convince ourselves that this problem is just like the previous one. I think it is more difficult for younger technicians to resist the quick fix temptation. They have not seen as many problems, so their brain is less confused – it is certain the solution is whatever they have seen recently! Often the quick solution involves adding refrigerant. My brother Richard is a senior technician at his company. Having seen and experienced many things, other technicians often call him for help. Richard is also a joker, so they know they are going to have their tail twisted a bit when they call. Recently a young tech called Richard and said he could not get the suction pressure on an R22 unit above 50 psig even though he had added refrigerant three times and every time the pressure settled down to 50 psig. He didn’t understand why adding refrigerant did not raise his suction pressure. Richard asked him “how many pounds of refrigerant do you have to add to make the fan blow harder?” No reply. So he asks again “Say, I really don’t know, how many pounds of refrigerant DOES it take to make the fan blow harder?” Finally, the tech replies: “adding refrigerant won’t make the fan blow any harder no matter how much I add.” Richard then asks “so why are you trying to fix an airflow problem by adding refrigerant?” Of course there are several possibilities that could cause low suction pressure, but airflow is one of the most common. He could also have some type of refrigerant restriction or a metering device issue. However, more information is needed to differentiate these from each other. A high superheat and low subcooling could indicate an undercharge. A low superheat could indicate an airflow problem. A high subcooling and high superheat would point to a refrigerant restriction or metering device issue. The problem is that the tech was only looking at the suction pressure and nothing else. He had already decided what the problem was and how to fix it before actually finding the problem. To his credit, he did recognize that he was pursuing the wrong “fix,” that is why he called for help. The next time you can’t understand why your fix is not working, ask yourself if you are trying to make the fan blow harder by adding refrigerant. Then call Richard.

Dr. William Lipscomb

2011-04-16T06:46:00.000-07:00

I heard on the radio that Dr. William Lipscomb had recently passed away at the age of 91. I confess that I really had no idea who he was. I became a little more interested when the announcer reported that he taught chemistry t Harvard and had won the Nobel Prize for chemistry. There aren’t many people that have done that. Then I became really interested when they said three of his former students had also won Nobel prizes. To me, that is really a much greater achievement. The mark of a good teacher is not what he has done, but what his students have done. He accomplished more by being a great teacher than he could have possibly done individually. I had to Google him to learn more. When I did, I found out that he was a student of another famous Nobel prize winning teacher – Linus Pauling. One of the quotes attributed to Dr. Lipscomb was “For me, the creative process, first of all, requires a good nine hours of sleep a night. Second, it must not be pushed by the need to produce practical applications.” I love this guy and I never met him. Here is a Nobel prize winning Harvard professor saying he is motivated by a need for practical application. This week’s posting is dedicated to celebrating the life of a great teacher, Dr. William Lipscomb.

Digital Gauges

2011-04-07T16:41:00.000-07:00

Digital gauges are becoming more common. The first company to offer digital manifold gauges was Digicool. When the first Digicool gauge sets came out, only the air conditioning techno-geeks and tool hounds had them. It will still be a few years before most mechanics use digital gauges, but many companies that traditionally make gauge manifold sets now have a digital offering. The list includes companies like JB, Refco, Robinair, and Yellow Jacket. Even companies who do not traditionally sell gauge manifolds offer digital manifold sets, including Field Piece and Testo. Many of these are billed as digital system analyzers because they do more than read pressure. They also show saturation temperature and have a place to plug in a thermocouple temperature probe for reading line temperatures, providing all the information necessary to determine system superheat and subcooling. Many will calculate the system superheat and subcooling and display them in real time. Some will even suggest what the target system superheat and subcooling should be based on the system operating conditions. There are several digital analyzers available that will also read vacuum in microns, doubling as a deep vacuum gauge. The strongest argument for digital gauges is accuracy. They are more accurate than the best bourdon tube gauges can hope to be. Accuracy is becoming increasingly important as system operating efficiency becomes more important.

The prices are coming down, but you will still pay a premium for a digital set over a good quality analog set. If you decide to take the plunge here are a few things to consider. When comparing the cost of a digital gauge set that reads deep vacuum, remember that a vacuum gauge alone can easily cost $200. Also remember that you are buying a manifold, not just a set of gauges. So sets that come on better manifolds cost more, just like analog gauge sets. One caveat when shopping - there are some very inexpensive digital gauge manifolds advertised on line that are intended specifically for cars and 134a. They will NOT work on systems which use other types of refrigerant, especially not R410a! These days you really should not consider investing in a high tech tool that will not work with R410a.

However, in the next few years I expect the same type of technology/price inversion that we have seen with electric multimeters where the older technology actually costs more than the newer technology. When Fluke digital meters were first being used in HVACR, they typically were more expensive than their analog counterparts of comparable quality. Now, a Simpson 260 analog VOM costs more than a Fluke 116 multimeter, and the Simpson is less resistant to field abuse and really less useful for the HVACR technician in general. The older technology electric meter technology is actually more expensive than the newer digital meters. I realize the analogy is imperfect: a Simpson 260 analog VOM is considerably more complex than a bourdon tube gauge. However, I expect digital gauge sets to be in the same price range as good quality analog bourdon tube gauge sets within 5 years.

Good Company

2011-04-03T19:36:00.000-07:00

It is often said that you can judge a person’s true character by the company they keep. One of the prime benefits to the two major instructor conferences is meeting with a large group of people who share your enthusiasm for teaching HVACR. My posting is a little late this week because I have been out of town pursuing my avocation – music. I play trombone in the Macon Symphony Orchestra. I say avocation because for me, it is like grown men going to baseball camp. I get to play with a really great group of musicians and they pay me for it to boot! We played three concerts this weekend, the last one for a group of orphans. Several kids were allowed to come up on stage and sit during one of the pieces. They literally were right in the middle of the orchestra. When one young man headed towards the lower brass, our tuba player, Heather, excitedly said “that’s my 7^th grade tuba player!” You see, Heather teaches band at a local school during her day job. He sat right in front of us while we played. Not only did he get to hear the orchestra, he saw his teacher performing in a professional group. Heather is hooked on teaching. She talks about her students, what they are doing, and how they are progressing. She has managed to find a way to combine two loves into a profession: music and teaching. I hope that is the way you feel about teaching HVACR. Teachers receive the unique opportunity to share in other people’s success. If you approach teaching this way, you will be rewarded by the company you keep. After several years of teaching, you will find yourself in good company as your students develop into professionals who love what they do and give you more credit that you deserve for helping them along the way.

Dry R22 Units

2011-03-25T16:49:00.000-07:00

I got my first look at a “dry” unit the other day. A wholesale house had one on its showroom floor with a big sign “we have dry units!” I looked at the nameplate to see what it said about refrigerant. A refrigerant amount was actually listed. Instead of the familiar “factory charge” preceding the refrigerant quantity, it had “Field Charge” and then the amount. I asked about coil matching for older systems. They recommend 1/2 ton smaller condenser than the original for heat pumps and the same size condenser for air conditioning. Then I asked about warranty and they said the units came with a 5 year compressor warranty regardless of the coil connected to it. They pointed out that this was less than the warranty on new matched equipment. Many of the units are being sold to replace condensing units that have been stolen or chopped up in place, often in rental property. Another wholesaler requires you to take coil measurements and then uses software to try and figure out the coil SEER. If the calculated SEER is less than 13, they recommend against buying the dry unit. Companies that just a few years ago were cautioning against the perils of mismatches units are now selling units that will almost certainly be mismatched. They cannot provide any meaningful charging chart without knowing what coil is on the other end of the system.

If you do decide to install a “dry’ unit, make sure and follow good refrigeration system installation practices. The fact that you are creating your own special blend of equipment makes it all the more important to be careful, not careless. It would be wise to treat the job like a compressor burnout. Flush the lines and coil, install a filter drier, pull a good vacuum, and weigh in the charge using an accurate digital scale. You can see more about line flushing at Mainstream Engineering. They sell a flush designed for this type of use. You will need to adjust the data plate charge for line length and possibly coil mismatch, but the nameplate charge should be in the ballpark unless you have very long lines. I think it might be wise to start a little under, so I would not adjust for line length until after starting the unit. I found a good set of instructions for installing dry systems online provided by Century, a supplier that is offering dry units. No, these are NOT the folks who suggested the 1/2 under ton heat pump coil adjustment. The link to the guide is:

http://www.centuryac.com/DryChargeInstructionsandchart.pdf

Spring Fever!

2011-03-19T16:11:00.000-07:00

Spring is always a busy time for events and meetings. The state SkillsUSA Championships are going on across the country. I spent the day this past Friday at the Georgia International Convention Center in Atlanta viewing the competition. Shumate Mechanical provided all the judges for the HVACR competition. I was very impressed by the way they interacted with the students encouraging and teaching them. Kudos to Shumate for going out of their way to help with the SkillsUSA Contest. I was also impressed by the poise and professionalism of all the contestants. It is not easy to work under a microscope with judges and spectators peering at you while you work. They only had 18 minutes to complete each task, adding to the stress level. But despite these pressures, they all held up admirably. Along the way, the students competing learn more than HVACR skills, they learn something about themselves. Taking up the challenge and seeing it through requires a lot of effort above and beyond the normal demands of most HVACR programs. I was very proud of the preparation and hard work Keith Watermann from my program put into the competition and his hard work showed. The winners of the state contests will meet in Kansas City later this summer June 19-24 for the national championships.

The National HVACR Educators and Trainers Conference starts Sunday, March 20^th in Las Vegas. However, if you are not registered already you will miss it because it is sold out. I spoke with Howard Weiss, and he said he hated to keep people out, but they have reached the maximum number of people the fire code will allow in the room! If you are lucky enough to be registered, be sure and say hello to David Skaves, my writing partner on Fundamentals of HVACR. He will be at the Pearson booth and he will be speaking at 9:15 on Monday on Strategies for Connecting with Today’s Student in the Age of Electronics.

If you missed the Las Vegas show, you can still catch the HVACR & Mechanical Instructor’s Workshop in Landsdowne, Virginia at the National Conference Center. This longest running HVACR Instructor’s workshop was started by ARI and today is supported by an impressive list of industry heavy hitters including AHRI, ACCA, ACTE, CARE, HARDI, HRAI, NAOHSM, NATE, PHCC, RSES, SkillsUSA. It is March 23-25 and there is still room. It is too late to register online, but you can still register at the Conference Center. The Conference is free if you stay at the National Conference Center. There is a $65 per day fee if you are staying elsewhere. Freddie Williams will be there at the Pearson booth. He is the author of the MyHVACLab material. Freddie is the man to talk to if you have questions about using online material in your program. Besides being the author of MyHVACLab, he has extensive experience with both Blackboard and Angel. If you cannot go to anything this year, just remember next January to start planning your strategy for attending one of these events. It does take some planning, but it is worth the effort.

I-Phone, The HVACR Service Tool of Today

2011-03-11T04:12:00.000-08:00

Do you have an I-Phone on your list of required service tools? I can not help but notice the increasing number of students in my classes that regularly use smart phones, I-Pads, and laptops. One student brings in his I-Pad and follows along on MyHVACLAb while I am lecturing. However, creative phone use goes well beyond using MyHVACLab. Students are looking up compressor data, working with PT charts, comparing different gauge sets, and pulling down articles posted on the web. I-Phones, Androids, and I-Pads are not really phones, they are hand held computers that are always connected to the internet. Oh, and they can be used for phone calls too. So while discussing PT charts, superheat, and subcooling I notice that four or five of my students are looking at their phones rather than the chart I am displaying. Why? They are using the free Bitzer app that puts a PT chart on their I-Phone. When discussing different gauge sets, one student shows me different models he has found, asking about the pros and cons of each. Copeland has just announced that they have released an app that gives a complete reference of their compressor data. Add to that the many smart phone accessible standard web pages with service data and you start to see that a smart phone really becomes a very useful service tool, connecting the technician with more service literature and data than could be carried around in printed form. More than ever, I see the job of the instructor as teaching our students how to intelligently use this information. Having access to a mountain of information does not make you a technician. You have to sort out the useful form the junk, and you need to know how to apply the information to solve problems. It is more important that students understand how to use this information than it is for them to memorize any particular piece of information. Rather than restrict the use of phones in class, I allow students to use them so long as it is not for texting their girlfriend. Allowing students to use their phones in class can be a little intimidating because you realize that you do not completely control the flow of information. That is OK. I do not see my job as one of stuffing information into my students craniums. That is their job! I try to think of myself not as a walking air conditioning encyclopedia, but as a coach whose job is to get the best out of each member of my team. I need to figure out where the gaps in understanding are and guide each student to improve their understanding of the information. If you allow phone use in class, inevitably someone will be texting their girlfriend rather than looking up compressor data. They are easy to spot. They don’t ask any questions or participate in the general discussion. The HVACR app masters are looking up PT charts for some refrigerant you never heard of before, pummeling you with questions and sucking in information at a breathtaking pace. The next generation of technicians is adapting the tools of their generation to the problems they face today. Smart phones are the service tools of ~~tomorrow~~ today.

Consensus Appliance Agreements Act

2011-03-02T17:07:00.000-08:00

In the February issue of the RSES online Journal John Iwanski discusses the current proposals for the Consensus Appliance Agreements Act and new Energy Star standards. These are still proposals, not law, but they could definitely have a major impact on our industry. The most significant thing I see is that efficiency minimums would be different for different sections of the country. An 80% furnace would be legal in Georgia, but not in Maine. Or more interesting, Arizona would have different standards than Colorado or Texas. A number of industry organizations were involved in the negotiations, among them AHRI. The EPA is also proposing changes to the Energy Star program. To read more about the Consensus Appliance Agreement Act or the Energy Star proposal, go to

RSES

Actual Bill

Energy Star Proposal

Positions of Industry Organizations

PRO

ASE Alliance to Save Energy

AHRI Air Conditioning Heating and Refrigeration Institute

CON

HARDI Heating Air Conditioning and Refrigeration Distributors International

Thermostat Recycling

2011-02-24T15:46:00.000-08:00

What do we do with all these old mercury bulb thermostats? Very few contractors still install new mercury bulb thermostats, but they remove them every day. When I asked a local wholesaler a few years ago about thermostat recycling they proudly said “we don’t sell any.” I congratulated them on their eco stewardship and forward thinking and asked, “so what do I do with the mercury bulb thermostats that I take OFF?” One suggestion was to leave them with the customers. That makes it their problem, not mine. However, that probably increases the likelihood that the thermostat will be tossed in the trash. Besides, our customers expect service; that is what we are paid to provide. Service includes more than fixing machines and changing parts. Many thermostats, including digitals, include the little paper admonishing us to “dispose of properly” without giving a clue as to how to do that. That is where the Thermostat Recycling Corporation comes in. TRC is a non-profit corporation voluntarily founded by thermostat manufacturers Honeywell, White-Rodgers and General Electric for the purpose of collecting and properly disposing mercury-containing thermostats. TRC now represents nearly 30 manufacturers that historically distributed mercury-containing thermostats in the US. TRC’s commitment to collect and properly dispose of mercury-containing thermostats reflects its members’ commitment to keep those thermostats out of the solid waste stream. The program is simple. Participating wholesalers receive TRC collection bins. You just put the old mercury bulb thermostats in the collection bin at the wholesaler. The wholesaler sends the thermostats to TRC and TRC sends the wholesaler back an empty bin. TRC then arranges for the mercury in the mercury bulbs to be recycled. The HVAC contractor’s sole responsibility is simply to take the thermostats to a participating wholesaler. The program does not cost the contractor or wholesaler anything; TRC picks up the tab for the cost of the bins and shipping. HARDI, Heating, Air Conditioning, and Refrigeration Distributors International, is a partner in promoting thermostat recycling through TRC (read about it). For more information on the thermostat recycling program, check out the TRC website or ask your local wholesaler about the program. We all have a stake in this. Not just to prevent pollution caused by discarded air conditioning parts, but to promote our industry as a clean industry acting responsibly to take care of our own mess.

HVAC/R Language

2011-02-19T05:39:00.000-08:00

A little over a year ago I posted an article on acronyms. Today I am expanding on that idea and offering suggestions on how to avoid confusing your students with HVAC/R techno-speak. We have our fair share of acronyms in HVAC/R. Used properly; acronyms speed up communication by reducing long polysyllabic phrases to a few letters. For example, speakers would get a bit winded if they used the phrase “heating, ventilating, air conditioning, and refrigeration” repeatedly in a conversation. The abundance of industry specific acronyms and the use of more than one acronym for the same item can be truly bewildering to students. For example, one major valve manufacturer uses the acronym TEV to represent “Thermostatic Expansion Valve,” while another uses the acronym TXV for the same thing. They do not represent two different types of components, just two different ways to abbreviate the same words.

When introducing a new topic, using acronyms can lead to confusion and misunderstanding. Worse, students can start to pick up the jargon, but use it incorrectly. It can be difficult for teachers who have had years of experience with HVAC/R techno-speak to remember that the acronyms we casually throw around often have no meaning for our students. Imagine listening to a lecture in which every important concept was in Russian! For example: “The evaporator delta T is controlled by the TEV adjustment, the return air wb, and the CFM.” Now I believe that most any air conditioning instructor understands this sentence, but it is essentially unintelligible to many air conditioning students. It might as well be in Russian! Replacing the HVAC/R specific jargon with the wingdings font it looks like “The evaporator delta T is controlled by the TEV adjustment, the return air wb, and the CFM.” THAT is what this sentence looks like to a new student!

In general it is a good idea to resist using an acronym for something until that item or process has been discussed. Otherwise, the acronym will appear to students to be a mysterious grouping of letters used by air conditioning shaman to communicate with each other. The acronyms and jargon become a secret language which they are not familiar with. I believe that acronym free language promotes better understanding.

Of course, students must still learn the HVAC/R language. Having a solid grasp of the terminology is necessary to make use of essential technical literature produced by equipment manufacturers. Once they are understood, acronyms help us communicate. Can you imagine actually writing out or saying positive temperature coefficient thermistor every time we disused PTC devices? However, the acronyms must first be explained and defined before they are used. It is much easier to remember an acronym if you understand what the letters stand for. When using an acronym for the first time make sure and explicitly spell out what the letters represent, this will increase student’s understanding and retention of the term. It also helps for the students to have a good mental picture of the object or process being described. They are far more likely to remember what Δ T (Delta T) stands for if they have actually measured a temperature difference and you have discussed it in class. That way the abbreviation is not an esoteric piece of jargon attached to something they don’t understand, but a name for something they have done. In Fundamentals of HVAC/R, we always use the complete word or phrase before introducing an acronym. It helps to explain concepts plainly. After introducing the concept, we give the technical terminology that is used to refer to the concept. The students are more likely to remember the terminology if it is logically connected to something they understand.

Fundamentals of HVAC/R has a unique abbreviation and acronym dictionary to help students learn the language of HVAC/R. Students can find out exactly what is meant by a particular acronym or abbreviation in Appendix C which lists the definition of common acronyms and abbreviations used in HVAC/R. The acronym dictionary is very useful when students are reading industry literature and need help with a particular abbreviation or acronym. For definitions of acronyms the students use when texting each other you will have to refer to another reference, acronymfinder.com

BFN GTG

HVAC/R Instructor's Conferences Coming in March

2011-02-10T17:26:00.000-08:00

Two national instructor’s workshops are coming soon – one on the west coast and one on the east coast. The HVAC Excellence National HVACR Educators and Trainers Conference is this coming week March 20 – 2 at the South Point Hotel in Las Vegas Nevada. The HVACR & Mechanical Instructor’s Workshop is later the same week, March 23 – 25 in Landsdowne Virginia. This workshop is sponsored by a group of eleven industry organizations, including AHRI who initially started this annual workshop over a decade ago. Both conferences have an impressive list of speakers and topics. David Skaves will be speaking at the Las Vegas conference. He is co-author of the new AHRI text Fundamentals of HVAC/R. If you can find a way to attend one of these conferences you won’t be disappointed. They are well worth your time. Unlike generic teacher’s conferences that target all subjects, these are specific to our field. And unlike industry showcases like ComforTech or the AHR show, these are specifically for teachers. As a result, everything you see will have a direct application to teaching HVAC/R.

I know that times are tough and getting funding and permission to go is difficult. When presenting the idea to your school administrators be sure to forward a copy of the program from the conference(s) that you want to attend. Both the National Educators and Trainers Conference in Las Vegas and the HVACR & Mechanical Instructor’s Workshop have well done professional programs on the web (click on the conference name). Be sure to note the large number of educational sessions. There are literally more sessions than you will have time to attend. Point out that attending will keep you informed about emerging technology like communicating systems. Point out that by attending you will be better positioned to integrate green mechanical concepts into your curriculum as a result of attending the conferences.

Interactive Programable Thermostat Simulators

2011-02-05T06:43:00.000-08:00

Have you ever found configuring , programming, or setting a digital thermostat somewhat confusing? While the new digital do-it-all thermostats are really cool, they can be confusing to set up. If you don’t configure them correctly, you may be unpleasantly surprised at the system operation. Of course you need to read the instructions. These are not for shoot first and read later service cowboys. However, you may not want to be reading the instructions for the first time on the job. Open the box and read the instructions before you arrive to install the thermostat. Most will operate on batteries, they do not have to be wired to be configured and set. Put batteries in and become familiar with the thermostat before arriving on the job. If you already know the system type, you can perform most of the configuration before arriving on the job. If you would like to play with a touch screen thermostat but don’t happen to have one handy, you can often find interactive simulations on line. These let you configure and program the thermostat using the exact same touches, only the touches are mouse clicks. Here are a few to get you started

Honeywell VisionPro

Honeywell Prestige (downloads a file that you must run)

Rheem 500

Aprilaire

Lux

To learn more about HVAC/R check out Fundamentals of HVAC/R

New Age Digital Tools

2011-01-29T06:49:00.000-08:00

I am a big fan of tools that make my work easier. Tools that improve your efficiency not only make your life easier, they make sense economically. The most expensive part of a service call is the service tech. Your time is more valuable that most of the parts you put on. I don’t mean what you receive in your paycheck, but what you cost the company. You cost more than the parts. Saving your time saves the company’s money. I know one contractor that understands this. He does not want techs trying to work with worn out or inappropriate tools. He understands that the time they spend trying to work with the wrong tool costs him money. So his company supplies all the tools for his techs and even replaces them when they are worn or lost. Today’s technicians can benefit from a wide array of technology driven new-age HVAC/R tools. Digital everything! Now technicians can use digital tools to measure pressure, temperature, superheat, subcooling, vacuum, relative humidity, dew point, wet bulb temperature, weight, air pressure, barometric pressure, air speed, CO, CO2, and combustion efficiency just to name a few. I did not even include all the electrical measurements available with today’s multi-meters. Indeed, there are many tools available that measure several system characteristics. I must admit that when I look through a catalog of a company that carries several lines of these tools I feel like a kid again looking through the toy section of Sears Christmas catalogue checking off every shiny toy. I want this, I want this, …It would be easy to spend $10,000 on inexpensive digital tools. But since that exceeds the weekly take home pay of your typical service tech, we have to make some choices. The parameters I use in deciding are

Does it do something that I need to do often?
Is it really superior and faster than what I do now, or is it just digital?
Can it do something that I can’t do now?

So by all means, arm yourself with an armada of new-age digital tools, but take time to assess what the new tool will do for you before you invest your paycheck. Otherwise, you could end up with a large collection of expensive digital toys.

If you would like to learn more about HVAC/R, check out Fundamentals of HVAC/R.

Poly Who?

2011-01-24T04:16:00.000-08:00

The emergence of HFC refrigerants has added a new set of confusing chemical names and properties with which the HVAC/R technicians must be familiar. One of the more confusing developments in the refrigeration industry in recent years has been the plethora of impossibly difficult to pronounce polys used for refrigerant oil with the new HFC refrigerants. There are several synthetic lubricants with multisyllabic names that begin with poly: polyalkylene glycol, polyol ester, and polyvinylether. Polyol ester is actually “short” for neopentyl polyol ester. To make discussion of these chemicals possible, they are generally referred to by three letter abbreviations: PAG, POE, and PVE. Polyalkylene glycol(PAG) is widely used in car air conditioning systems, but is generally not used in hermetic and semi-hermetic systems because of its lower electrical resistance. Currently, polyol ester, POE, is the primary lubricant in hermetic and semi-hermetic systems using HFC refrigerants. POE has been used for years as a lubricant in jet engines. One advantage POE has in refrigeration is that it is compatible with a wide range of refrigerants including CFCs, HCFCs, and HFCs. Another important characteristic is relatively high electrical resistance, making POE superior to PAG for hermetic and semi-hermetic systems. A major disadvantage is that POE is very hygroscopic; it readily absorbs water. Water is never welcome in a refrigeration system (unless the system is a lithium bromide chiller). However, water in a system with POE is a particularly bad set of circumstances. To understand why this is such a problem you need to understand how POE is made. POE is made by a reaction with acid and alcohol which yields water and POE. Like many chemical reactions, it can be reversed. Add water and heat, and POE reverts to acid and alcohol. The hydrolysis of POE creates goo that clogs metering devices, filters, screens, and oil holes. Filter driers are absolutely essential for all systems with POE because of this added water hazard. Even deep evacuation will not adequately dehydrate a POE system if there is already any water in the POE. Some links to sites that discuss these lubricants are PAG, POE, and PVE.

Hero Convoy

2011-01-13T17:49:00.000-08:00

I was in Nashville this past weekend nervously watching the weather reports and trying to determine exactly when I needed to start my six hour trip back home in order to beat the impending winter storm. There was heavy traffic all the way, all manner of cars, trucks, and commercial vehicles. Maybe they were also trying to beat the storm south. Mixed in with the regular traffic were several convoys of cherry pickers from several states. There was a convoy of 30 bucket trucks from a power company in Michigan. I also remember another convoy of trucks from Kentucky. A lot of my pent up concern and worry melted away when I saw these convoys of heroes because I knew good people were positioning themselves to help. While the rest of us were trying to run away from the storm, they were running towards it. What does a hero look like? If you are cold and out of power, the guy in the bucket truck is way better than superman. A hero is someone who leaves the comfort of home and travels to places where the weather is guaranteed to be wretched so they can hang from a pole and play with wires that could have thousands of volts traveling through them. Heroes aren’t super human beings that accomplish awesome tasks easily without effort or suffering. No, heroes are everyday folk who put forth the effort and bear the suffering for the sake of the rest of us. Thank God for the heroes in the bucket trucks!

Absolute Zero

2011-01-10T05:27:00.000-08:00

Gary Reecher sends me information from time to time. One of the nice things about having a network of friends is that you don't have to know everything, you can use the network's collective knowledge. I am blessed with a good network. Gary recently sent me this on a show he saw on NOVA about absolute zero and I wanted to pass the information along. It is rare to find television that is both entertaining and educational, but NOVA usually accomplishes that. What follows is the text of Gary's message.

Many times when one watches television it is to be entertained. Occasionally a program not only entertains but educates and enlighten. That is the instance of NOVA's Absolute Zero series.

Our local PBS channel re-aired this 2009 2 part series. And here is an outline of the series.

NOVA brings the history of cold to life with historical recreations of great moments in low-temperature research and interviews with historians and scientists to reveal how civilization has been profoundly affected by the mastery of cold.

Hour one of the program (The Conquest of Cold):

reports on the pioneering experiments done by Robert Boyle to understand what cold was.
presents how the first temperature scales were determined by Daniel Fahrenheit and Anders Celsius.
recounts how Guillaume Amontons first came to speculate that cold had an absolute limit.
explains how scientists came to understand what heat and cold actually were, including the incorrect caloric theory proposed by Antoine Lavoisier.
reports on the first industrialization of cold through ice sales.
details how experiments on the steam engine led to the development of artificial refrigeration.
profiles how Clarence Birdseye and Willis Carrier harnessed the cold to create frozen foods and air conditioning.

Hour two of the program (The Race for Absolute Zero):

features the race between nineteenth-century scientists James Dewar and Heike Kamerlingh Onnes to become the first to liquefy hydrogen, the last of the so-called permanent gases.
notes how unexpected events in the study of cold led to new areas of research, including superconductivity and superfluids.
details how Albert Einstein came to predict that a new state of matter—one that behaved according to quantum mechanical rules—could be produced at temperatures just above absolute zero.
shows how particles would change into overlapping waves in this state of matter, known as the Bose-Einstein condensate.
details the race among scientists to create this condensate.
describes how one scientist found a way to slow down the speed of light.
reports on research being done to develop quantum computers.
shows how far down the scale scientists have traveled and explains why reaching absolute zero is not possible.

If one is interested in the history and development of refrigeration I would give this series a 2 thumbs up.

More information is available http://www.pbs.org/wgbh/nova/zero/ including instructor resources for using this program.

Christmas Spirit

2010-12-25T06:27:00.000-08:00

This will be a short post. I ran across this listing of organizations that help people in creative ways by redirecting resources we already have and i had to share it. I believe these good people have the right idea. Merry Christmas!

http://www.cnn.com/2010/LIVING/12/23/cnnheroes.12.ways.of.giving/index.html?hpt=C1

The Treasure Hunt

2010-12-23T08:00:00.000-08:00

Although this blog normally features articles on air conditioning instruction, I am taking the liberty of writing on the current Christmas Season in this one. It is nearly Christmas and many of us are neck deep in the annual last minute treasure hunt that takes place this time of year. We scour adds and the internet looking for elusive gifting treasure. We sacrifice time, health, and wealth in an effort to secure those must have gifts in our annual treasure hunt. The tension is heightened because we compete against each other; there are only so many baby bobble heads to be found! Even if you are not particularly religious, you probably have heard the famous verse from Luke 12:34 “For where your treasure is, there your heart will be also.” The normal interpretation of this verse is to point out that you invest your time and money in what you really love. I think most people recognize the truth in this statement even if it can make us uncomfortable. However, I would like to turn this around a bit and suggest that your heart will locate your treasure for you in this mad scramble treasure hunt. What would you miss most in your life if it were suddenly taken away? The answer is probably not something, but someone. Hopefully several someones. Afterall, why are you trying to locate the baby bobble head? To see the look of joy on someone’s face. So in the din of the treasure hunt let your heart guide you to your treasure. My treasure greets me in the morning, sings in the choir, plays in the marching band, and studies at Vanderbilt. I am a wealthy man!

Cool Toys for HVAC/R Instructors!

2010-12-16T16:41:00.000-08:00

Document camera? I thought this thing was an air conditioning component magnification system! I have been learning to use my new toys this quarter. I was given a document camera and video projector for my class room. Many people know these things as Elmos because that is who developed the first ones. If you are unfamiliar with them, they are able to zoom into a document placed on them so that you can project it to a screen using a video projector. That is OK, but what I use it for is projecting images of components and tools. Put a defrost board on it, zoom into the defrost setting jumpers, and show how to set the time on an electronic time-temperature defrost board. Look at the color bands on resistors. Ohm the coil out on a relay and show the meter as you ohm the coil out. Wire a simple circuit and operate it, then measure the voltage drop across the switch. Disassemble a TEV and show the difference between an internal and external TEV. Show the difference between the wire gauge of the run and start winding on a split phase motor. I am just getting started, but I think you get the drift. You can show detail in real time and everyone can see and follow what you are doing even better than if they were standing beside you. Having drawn many extemporaneous works of art on the white board, I still sometimes revert to my older chalk and talk methodology. Elmo helps there as well. If I really feel the need to scribble, I can draw on a piece of paper and project the drawing. If the scale is not quite right, the zoom lets me show it off to full advantage and I don’t have to clean the white board afterwards. I have an internet connected computer in the podium as well. The video projector works great for showing MyHVACLab on the screen. When we discuss the questions at the end of the units, I project the e-book from MyHVACLab. Then I can show relevant information from the book as we review the unit and the students can follow along in their textbooks. I use the mouse to point out any particular coverage in the book I want to highlight. Of course the video projector also works for showing powerpoint presentations and video clips, but I have not shown any videos yet because I am too busy showing all the cool HVAC/R parts. I have a large collection all around my podium of things I have confiscated from the lab, including a few unit panels. If someone asks a question about a part I don’t have I am likely to find one by the next class. I got the idea I wanted to show the phase shifts caused by inductive reactance and capacitive reactance. The electronics department loaned me a digital dual trace oscilloscope that is small enugh to fit on the Elmo. I am going to build a circuit to show phase shift on the oscilloscope. I know lots of text books have drawings of this, but I don’t think many students pay a lot of attention to them. I am hoping when they see the shift occur right in front of them on the big screen in real time the information will sink in. At the very least, I know that I will have a good time playing with my new toys. I hope my students will see how cool this all is and want to play too.

A Few Quick Service Tips

2010-12-09T18:30:00.000-08:00

Technicians often feel pressure to work quickly. Many technicians have quotas- either the number of calls per day or revenue dollars per day. Even without an explicit quota, everyone works on a quota. You have to make money for your company or they cannot afford to employ you. If you are working for yourself, you have to make money to pay your bills. It can be difficult to put this out of our mind when we are working. There are some tricks you can use to maximize your productivity that are helpful, and there are some shortcuts that can get you in trouble. I believe that you save time overall by not skipping steps, but you can arrange your work flow to avoid wasted time. First, take the time to talk to the customer to find out what the complaint is and ask questions. Often, symptoms that the customer has noticed may give you some clues. Next, I always want to see the thermostat to verify that it is set correctly and calling for the system to operate. There are a significant number of customers that do not know how to operate their systems, especially with today’s programmable touchscreen digital thermostats. If the indoor blower is not running, set the fan switch to “On” to see if it comes on. If it does you know that the indoor unit has power, the transformer is providing control voltage, and of course that the fan and its control are working. If the fan does not come on, you have a good idea of where to start checking. Always do the easy stuff first. This is not just being lazy, it is being time efficient. It is never wrong to check the air filter; that should be done on each call anyway. If the filter is blocked you are wasting your time trying to adjust the charge. More often than not, the problem is a relatively simple issue. While you are changing the filter, take a look at the vent if the system is a gas or oil furnace. I have found vents rusted through while under a house checking a stopped drain in the summer. If you are the last HVAC/R technician at someone’s house, you have a responsibility for the safety of the system. For more ideas on efficient troubleshooting, check out Unit 86 Troubleshootng in Fundamentals of HVAC/R.

New R22 Units Coming!

2010-12-02T04:24:00.000-08:00

The drama over the R-22 phasedown has been something of a soap opera. Just when you had adjusted to the fact that they killed off your favorite character, voila, they are raised from the dead! Manufacture of new equipment charged with R-22 stopped January 1, 2010. However, Carrier, Goodman, Lennox, Nordyne and Rheem are reported to be planning the production of dry R-22 condensing units for the replacement market. How is this legal? Well, these are for replacement, not new installation. And,. they are not charged with R-22 - at least not by the manufacturer. A dry unit is one that is evacuated and charged with dry nitrogen, not refrigerant. The units can be used to replace existing R-22 units and then charged in the field. The replacement installer needs to purge the nitrogen charge, evacuate the entire system instead of just the lines and coil, and then charge the system with R-22 according to factory recommendations. Alternatively, environmentally conscious contractors could opt for a non-ozone depleting R-22 replacement. Check out Fundamentals of HVAC/R for more specifics on how to properly install an air conditioning system.

These dry R-22 units would give customers an option other than replacing their entire system with a new high priced 410A system. In today's economy customers often simply cannot afford to purchase a complete R410A system. They are left with a few bad options. Do without, or put money into repairing an aging, inefficient piece of equipment that really should be replaced.

There are many questions to be answered, such as efficiency certification and avoiding potential legal landmines with the EPA. In some people’s minds it is not a good idea because they don’t believe today’s technicians properly evacuate the lines and coil on current systems. If these same folks charge an entire system without evacuating it, the head pressure would be so high that the system would likely not run long, if at all. This might be a blessing in disguise. If every unit they put in refuses to work, at some point even the most obstinate slacker would have to suspect that they are not doing it right. Success will depend more than ever on using skilled technicians that have the proper training. For more specifics, read the article on the Heating Air Conditioning and Refrigeration News website. R-22 has remained readily av available and the price has not spiked as much as had been predicted. Both of those situations may change if several major manufacturers start selling new products that require R-22 refrigerant. There are several R-22 work a likes now, but you had better check with the manufacturer before charging a new product with one of them. The equipment UL rating and manufacturer's warranty could possibly be voided by using an alternate refrigerant. For older equipment whose warranty has already expired, that is not too much of an issue. But for new equipment that still has a warranty, losing the the warranty would be a problem. Right now getting their efficiency certified is an issue. Air conditioners cannot be sold until they are certified to meet the minimum SEER rating. AHRI removed all their R-22 listing, thinking we were done with new R-22 systems. Stay tuned - it is bound to be interesting!

Count Your Blessings

2010-11-23T13:49:00.000-08:00

Last year I posted a thanksgiving article citing reasons for folks in HVAC/R to be thankful, myself in particular. If you are teaching HVAC/R, I know that you are experiencing record record enrollment at a time when your financial resources are dwindling. Although your job is difficult, you do have a job. A very important one at that. Your classes are filled with good men and women who do not have a job and they are looking to you for help. Both the economic situation and my reasons for being thankful in the face of adversity remain the same, so I am reposting last year's comments.

At thanksgiving we should all take time to reflect on our blessings. For me this has been a great year filled with an abundance of blessings for which I am truly thankful. Unfortunately, many of my students have had setbacks in their life the past couple of years. I suspect many of your students have as well. We are seeing a wave of students who are preparing for a second or third career because their previous career was abruptly terminated. The plant they worked for closed, the building contractor they worked for has no projects, or the company they worked for has gone out of business. These are good people whose life has been turned upside down. It would be easy for them to concentrate on the past and what they have lost rather than what lies ahead. Dwelling on past misfortunes can be harmful to your health, adversely affect your present and threaten your future. I believe that one of the most important things we can do for these students is to keep them focused on their future. I have seen economic downturns and displaced workers before and I know the end game. These folks will merge their current skills, knowledge and experience with the knowledge and skills they will learn in their HVAC/R program to quickly become leaders in their new field. HVAC/R needs them.

Here is a list of a few things today’s air conditioning students can be thankful for.

The need for heating, cooling, and refrigeration systems is only going to increase.
They are starting a new career in a field that desperately needs skilled workers.
There are still openings for skilled air conditioning technicians even during this economic downturn.
Installation and repair of HVAC/R systems cannot be outsourced to foreign country.
The wages earned will remain competitive because the work cannot be done by unskilled workers.
They will enter the field with training for new refrigerants at a time when this knowledge is crucial.
They will enter the field with training for new high efficiency systems at a crucial time as well.
They are entering a field that is consciously increasing the level of professionalism and certification.
They have experienced HVAC/R educators to help them make this career change.

I wish for all of you an abundance of blessings for the coming year.

CO Scare

2010-11-11T16:09:00.000-08:00

I think that warnings about common hazards can become so commonplace that we don’t pay enough attention to them. We need something to wake us up. This week I received a wake up call when one of my students showed up to class explaining that his entire family had been suffering from carbon monoxide poisoning. He had missed over a week of classes and had come by once to explain that everyone at his house was sick. His family physician suspected something was up after treating everyone in the family for symptoms that mimicked flu. The doctor confirmed that they were indeed all suffering from CO poisoning. A little investigation revealed that the vent for the furnace in the attic had never been connected. There was a vent pipe, but it ran to within a foot of the horizontal furnace and stopped. The furnace was changed when he purchased the house. He showed pictures of the furnace. It was a model that can be difficult to connect vent to because the vent comes through the front access panel. I imagine the installers did not have the right parts, left it for “later” and forgot about it. The HVAC/R contractor did not get a permit, so there was no county inspector to find the problem. The home inspector did not catch it, from the attic access the vent looks like it is connected. The student thought that he had combination smoke and CO alarms. Turns out, they were just smoke alarms. So an obvious safety hazard that is easily corrected went unnoticed until the weather turned cold. The good news is that nobody died, the house now has CO alarms, and the source of the problem was found and corrected. It is scary to think what the end result could have been if the problem had not been recognized or if the weather had stayed cold for a longer period of time.

More people are sickened or killed by carbon monoxide poisoning than any other type of poison. The Center for Disease Control and Prevention (CDC) reports that each year more than 500 people in the United States accidentally die from carbon monoxide. An estimated 10,000 people in the U.S. are treated for CO poisoning in hospital emergency rooms annually. It is believed that many more people suffering CO poisoning are misdiagnosed, or never seek medical care. This is because the symptoms of CO poisoning are very similar to influenza symptoms. One big difference is that influenza causes a fever and CO poisoning does not.

Carbon monoxide is an odorless, colorless gas that is highly poisonous. It is formed by the incomplete combustion of carbon based fuels, like natural gas, oil, coal, or wood. Incomplete combustion can be caused by lack of oxygen, improper mixing of the fuel and oxygen, or too low a combustion temperature. A correctly adjusted gas or fuel oil flame should produce very low levels of CO. Ideally a correctly adjusted gas or oil flame should produce no CO, but realistically, most produce at least trace amounts. Solid fuels almost always produce large amounts of CO; that is why charcoal comes with a warning that it is not to be used inside.

HVAC/R technicians are in a position to help. We can make sure all combustion appliances in the home are burning correctly, insure there is enough combustion air for proper combustion and venting, and finally by making sure the vent system is adequate and working correctly. For gas and oil furnaces also remember to inspect the heat exchanger for leaks. The heat exchanger separates the combustion products from the air circulating in the home. Although a defective or cracked heat exchanger can contribute to CO poisoning, more obvious problems are frequently to blame. Stopped vents, loose or leaky vents, and lack of combustion air are common causes of CO. While every technician should learn to look for conditions that can lead to problems, testing is required to verify that a system is operating at safe levels of CO and that there is no CO in the house. Every technician should have an accurate CO tester. Household alarms are not a substitute. While every house with gas or oil appliances certainly should have CO alarms, they are not a replacement for an accurate tool for diagnosis. I highly recommend a seminar done by Bob Dwyer for COSA (Carbon Monoxide Safety Organization) Make sure and take advantage of the opportunity if you have a chance to attend one of his CO Safety Seminars.

There are many units in Fundamentals of HVAC/R to help explain how to achieve safe, efficient combustion for gas and oil furnaces, including

Unit 37 Gas Fired Heating Systems

Unit 38 Warm Air Furnaces

Unit 40 Gas Furnace Installation, Startup, Checkout, and Operation

Unit 41 Troubleshooting Gas Furnaces

Unit 42 Oil Fired Heating Systems

Unit 43 Oil Furnace and Boiler Service

Unit 44 Residential Oil Heating Installation

Unit 45 Troubleshooting Oil Heating Systems

There are many good web sites for more research on carbon monoxide poisoning. A few are listed below.

http://www.bbc.co.uk/health/conditions/carbonmonoxide1.shtml

http://www.cosafety.org

Speed Up Your Service Calls

2010-11-05T15:39:00.000-07:00

HVAC/R Technicians are under a lot of pressure to work quickly. The customer wants the problem fixed now. In the customer’s mind, the problem is fixed when the technician answers the door. If it were only that easy! The company also wants the technician to work quickly because time is money. The technician’s significant other wants the technician to work quickly and get home on time. Today people are so accustomed to downloading what they want, when they want it that they expect everything to come as easily and quickly. Life conspires to pressure the technician to repair HVAC/R equipment in the time it takes to download a movie. About the only way to actually accomplish this type of blitzkrieg service is to jump to conclusions and get lucky. It can you look brilliant to go right to the offending part on a hunch, replace it, and have the unit operating in minutes. But you can also look foolish if the unit quits operating before you get back to the shop. The customer now loses confidence in your ability. They can also feel cheated, suspecting that you did not check out the system thoroughly because you were there such a short time. From a practical standpoint, you have not saved any time if you have to return. In fact, your quickness has cost you time. I believe that being careful saves time in the long run and builds your reputation as well. Here are a few ideas on real time savings. Before you go to the service call, you should

Study! Your knowledge is the most powerful weapon in your troubleshooting arsenal. Read texts such as Fundamentals of HVAC/R, subscribe to service magazines such as the RSES Journal, enroll in classes at your local Technical College, join the local RSES chapter, and attend manufacturer’s service seminars. There are so many excellent educational opportunities for the HVAC/R industry that there really is no excuse to remain ignorant. Each hour you spend learning about your trade will save you many hours later on.

Build a good service library. You can’t keep an entire HVAC/R service library on your truck, but you can keep a few of your favorites. Don’t sell your HVAC/R tests – you can use them in the field. Service manuals and bulletins from equipment manufacturers are also very handy. If you can afford it, get a laptop with wifi internet. Most Companies now keep very complete service information on their web sites.

Invest in quality tools. It always takes longer to do the job without the right tools. Don’t skimp on tools! Good quality tools that are made to perform the specific task at hand save you time. You can sometimes bang a motor shaft out of a blower wheel with a hammer and wood block, but it is so much faster and easier with a hub puller. And you will really cost yourself a lot of agravatino and time if you mushroom the shaft or warp the blower wheel.

Next week I will discuss some tricks to speeding up the call after you arrive on the job.

Are Your Capacitors Stale?

2010-10-30T14:03:00.000-07:00

A capacitor is a pretty simple device, basically a couple of rolled up sheets of aluminum foil or metalized film with paper or plastic between them. Any practicing service tech will tell you that service calls involving dead capacitors are common. Technicians that have been around for a few decades will also tell you that capacitors die a lot more now than they did twenty years ago. This is because the newer capacitors use a different electrolyte. The electrolyte in the “good old style” capacitors was polychlorinated biphenyl, PCB. PCB causes cancer, so it is no longer used. The newer capacitors are smaller and less expensive than the older PCB capacitors, but they are not as robust. The two most common causes of capacitor death are heat and over voltage. However, there is another less known cause: old age. Many capacitors have a shelf life. I have seen shelf lives listed as little as one year. The oxides on the metalized film break down when the capacitor is not in use, weakening the capacitor. They tend to self-heal during use. That is why a capacitor that cannot sit on the shelf for longer than a couple of years can last for ten years in use.

Always check the capacitance of any replacement capacitor with a capacitor tester or the capacitance scale on a digital multi-meter before using the capacitor. It may have already died of old age before you install it! Although a capacitor is a simple device, it is an extremely important part on most air conditioning systems. A bad capacitor can kill a system’s compressor. To protect your reputation and your customer’s equipment, only use capacitors that can pass the EIA-456 Highly Accelerated Life Test. The HALT test subjects a set of capacitors to 125 percent of their rated voltage and 10˚C above their rated temperature for 2,000 hours. For example, a capacitor that is rated at 5uf/440 vac, with an operating temperature of 70˚C, is tested at 550 vac and 80˚C for 2,000 hours. Two links for more detailed information on capacitors are

Aerovox

Genteq

Determining which capacitors to stock on your truck is another problem. There are so many sizes of dual capacitors that it is nearly impossible to have all the necessary sizes. American Radionic, AMRAD, has a solution – a multiple capacitor with enough sizes to cover nearly any application. Better yet, they will send instructors sample capacitors to use in your lab. These are great for demonstrating the effect of connecting capacitors in series and parallel. Their web site is AMRAD

Fundamentals of HVAC/R has coverage of capacitors and their effect in circuits in Unit 29 Electrical Power and Circuits, Unit 30 Electric Motors, Unit 33 Control Circuits, and Unit 83 Troubleshooting Refrigeration Systems. Unit 30 of MyHVACLAB has an interactive exercise on determining capacitance and a video on testing capacitors. Unit 83 has an interactive exercise on testing capacitors.

Simplify Parallel Calculations

2010-10-21T18:04:00.000-07:00

The total resistance in a parallel circuit is difficult to calculate because it cannot simply be added as in a series circuit. However, the total current flow in a parallel circuit is easy to calculate. It is simply the sum of the currents for all the individual loads. The famous parallel formula for resistances in parallel uses this concept. Dividing the resistance of each load into 1 calculates the current draw for each load at 1 volt. Adding these fractions gives the total current draw of the entire circuit at 1 volt. Since resistance can be calculated by dividing current into voltage, dividing the total circuit current at 1 volt into 1 volt gives the total resistance. I confess that I have used and taught this formula for many years without knowing why it works. Once I understood the reason behind the formula, it seemed far more logical and less imposing. Did you know that this works for any voltage you choose? We can use this to create a simpler parallel calculation.

I find that many of today’s digital students struggle with the fractions, common denominators, and all the trappings that go with fractions. One solution is to convert the fractions to decimals. But the decimal numbers you get when dividing whole numbers into one are always several decimal places to the right of 0, causing another own sort of confusion. My suggestion is to choose a voltage at least equal to the highest resistance; preferably, twice the highest resistance. That way, all the answers will have at least one whole number. This not only makes the answers easier for the students to deal with, it makes the decimals to the right of 0 less significant, so lopping off a few won’t have as big an impact on the final answer.

For example, with resistances of 15, 20, and 30 ohms choose 60 volts. Instead of trying to add 1/15 + 1/20 + 1/30 or their decimal equivalents, you are adding 60/30 + 60/20 + 60/15. Most people can add 2 + 3 + 4. Then, divide this total current, 9 amps, into the voltage we used, 60 volts, to get 6.6 ohms total resistance. OK, so I stacked the deck a bit. Another teacher’s trick – if you get to choose the questions, why not choose questions that make your life easier. After your students are adept at these “easy” problems, have them measure the resistance of some actual devices and do the calculations. This is where choosing to make the calculations easier really pays off. Anybody can make simple things difficult – the trick to teaching is to make difficult things simple.

A Story of Personal Courage

2010-10-16T07:19:00.000-07:00

Have you ever wondered how you would react in the face of personal tragedy? I have. When I read about tragedies in the paper or hear about them on the news, I find myself wondering “What if..?” Fortunately, I have never found out. Soon the business of the day drowns out my musings, and I return to the business at hand. However, the closer to home the tragedy is, the more difficult it is to dismiss.

Just before the start of this past summer quarter, my friend Bruce Arnold lost his 18 year old son Tyler in a motorcycle accident. Tyler was preparing to study air conditioning at Athens Tech and study with his dad. Bruce works in the field and takes classes in the evening. Bruce was so excited about his son going to school to study the trade he practices.

Only a parent can truly understand the feelings parents have for their children. You really cannot fathom how much you have been loved or how much of themselves your parents invest in you until you are a parent. When you are a teenager your parents unending questions about where you are going, what you are doing, and who you are going to be with are an incredible annoyance. Their interest in every detail of your mundane school day is perplexing. The reason is simple: parents have more interest in your safety and success than you do.

Nobody celebrates your victories and accomplishments more than your parents. I have been teaching longer than most of my students have been alive, and I know that my mother is still my biggest booster. I have a 20 year old daughter and a 15 year old son, and I know I get far more excited about their accomplishments than my own. That is why I know there can be no greater pain than losing a child. Truthfully, I hope I never learn what it feels like.

Bruce returned to school and completed his summer coursework. He explained that he felt compelled to come back to school because Tyler was so proud of his dad for going to college and so happy to be going himself. Many of Bruce’s friends counseled him to “put it behind him” and “go on with his life.” He couldn’t. Instead, he started a non-profit scholarship foundation in his son’s memory. He hired a lawyer to create the non-profit foundation, established a bank account for the foundation, started a web page to advertise his foundation, and is out personally raising money for the foundation. His goal is to raise money so other young men and women can realize their future, fulfilling their parent’s dreams. If you would like to learn more about Tyler or the scholarship foundation established in his name, go to http://www.thetylerbrucearnoldscholarshipfund.com/index.html

Where Do YOU Belong?

2010-10-09T10:29:00.000-07:00

You can tell a lot about someone by looking at who they hang with. The people and organizations you spend time with help form who you are and advertise to the world what you really think is important. I believe finding where you fit in is important. You may have heard people talk about networking: not a connection between machines, but a connection between people. Spending time with people that have similar interests and developing your common interests. Some of the benefits are obvious, like making valuable connections to folks that can help you. However, I believe part of the power of networking is that you find a group of people whom you enjoy being with. The truth is that most people are more inclined to put effort towards helping someone they know and like. Being with other people who share your interests makes all your activities more meaningful. Disneyworld is no fun by yourself; a big part of the magic in the magic kingdom comes from having fun with your family.

Joining an industry organization gives you immediate access to a group of people with similar interests. There are many groups organized around different aspects of the HVAC/R industry. There is a group for HVAC/R Technicians – RSES; a group for trades students – Skills USA; a group for Air Conditioning Contractors – ACCA; a group for HVAC/R Distributors – HARDI. If you teach HVAC/R you have some common interests with all of these groups. Every one supports HVAC/R education with resources and material. Trying to participate in all of these would probably not be possible for most of us, but joining and participating in one is doable for even the busiest folks. I suggest exploring what all of these groups have to offer, finding where you belong, and taking the plunge.

Each organization has an annual meeting where you can network with other HVAC/R folks, participate in training, see the latest in HVAC/R technology, and just have fun. If you have never been to a national HVAC/R convention, an opportunity coming up would be the National RSES Conference in Tucson, Arizona November 9 – 13.

Here is a partial list of HVAC/R organizations with links to their web sites where you can learn more about each one.

ACCA – Air Conditioning Contractors of America

ACTE – Association for Career and Technical Education

AHRI – Air Conditioning, Heating, and Refrigeration Institute

HARDI – Heating, Air Conditioning, and Refrigeration Distributors International

HRAI – Heating, Refrigeration, and Air Conditioning Institute

HVAC Excellence - Heating, Venitlating, and Air Conditioning Excellence

NAOHSM – National Association of Oil Heating Service Managers

PHCC – Plumbing, Heating and Cooling Council

RSES – Refrigeration Service Engineer’s Society

Skills USA

Understanding Relationships is Key

2010-09-25T12:58:00.000-07:00

During the quiet times between quarters, our team members will often discuss what students are struggling with, what WE are struggling with, and look for ways to address these issues. The other day we were discussing why many students have such a difficult time learning how to identify the common, start, and run terminals on compressors. A few other problem areas came up – reading diagrams, superheat, subcooling, and system charge compared to superheat and subcooling. Then it struck me what all these things had in common – they are all relationships. You have to compare two or more pieces of information to arrive at a solution. Over my years of teaching, I have noticed that the more abstract a concept is, the more students struggle with it. Identifying components is usually not a problem because that is very concrete, just putting a name with something you can see and touch. Memorizing definitions is also fairly straightforward, even if it is not very exciting. Most students can give us a pretty good definition of superheat. But we lose many of them when they have to actually measure it on a unit. We lose even more when they have to use that measurement, compare it to the manufacturer’s specification, and determine if the charge is correct. I believe if you made a list of all the most important things students should learn to do before they leave you would find the most important skills involve understanding relationships. I don’t know of a sure fire way to teach relationships. I think that people who have a good mechanical aptitude readily see relationships. Students that have difficulty understanding relationships need explicit instructions and lots of practice. Teaching something that is “obvious” to you can be difficult because you have to deconstruct your thinking process so you can explain how you accomplish a task that you do innately. For example, suppose you had to teach someone how to use a screwdriver. Do you know exactly how you hold it? How do you get the screw started? What do you do after turning your wrist a quarter turn so that you can turn the screw some more? I have actually had to teach people how to use a screwdriver and it was one of the most difficult things I have ever taught because I really did not know how to explain it. Admittedly, the screwdriver example is extreme. However, the same type of deconstruction process can be used to explain more analytical processes like measuring superheat. My prescription for helping relationship challenged students is to:

Analyze the task in detail – leave nothing out and assume nothing.

Teach the students the process in explicit detail making sure they understand each step.

Practice, practice, practice!

Patience, patience, patience!

Remember, if all the students could do everything easily on their own they wouldn’t need you.

Are You Practicing for Success or Failure?

2010-09-16T16:25:00.000-07:00

We are what we repeatedly do. Excellence, then, is not an act but a habit." – Aristotle

I would like to propose a slight revision to Aristotle’s line of thought: Success is not a condition, but a habit. Have you ever known someone that is lucky and seems to go from one success to another? It is sometimes difficult not to be envious of their success and wish we were so lucky. If the primary action you take towards becoming successful is to wish for success, chances are you will not find it. People are not successful because they are lucky; they are successful because they prepare for their success through repetitive practice. So the question is: “Are you practicing for success or failure?” You might ask “Who would practice for failure?” However, I have seen many students diligently practicing for their inevitable failure. They practice for failure by not preparing for class, arriving late, and making endlessly creative excuses for their failure to succeed. Eventually they become expert at failing – eliminating all chances of success. I will not tell you that if you work hard and put your best effort into everything you do that you will always be successful. But I can guarantee that if you do not work at being successful, you will fail. So you can take the sure thing – guaranteed failure, or you can put yourself out there and risk being successful.

The Strength Remains

2010-09-11T09:03:00.000-07:00

Nine years ago, I was working in my office at school when a teacher from down the hall came in and said that a plane had flown into one of the World Trade Center Towers. While I was searching for information about the first plane, the second plane hit the other tower. It was only then that I realized we were under attack. I believe the trade center towers were chosen because they became an icon of American strength. Rather than weaken us, the attacks strengthened us in many ways. We proved our mettle immediately following the tragedy. Stories abound about how people rose to the challenge: from police and firemen risking their lives to politicians speaking with one voice as Americans. My favorite story involves St.Paul’s Chapel directly across the street. Somehow St. Paul's survived the shower of debris and was transformed into a round the clock hostel, providing care and support for eight months to the rescue and recovery workers. Volunteers came from all over America to work there. So many volunteers came that they had to be scheduled and their time helping was limited to allow everyone a chance to experience the blessing of helping. People cried when their time was up and they had to leave.

The towers came down. The strength remains.

Are You Giving Your Students Cognitive Indigestion?

2010-09-03T14:24:00.000-07:00

One cold wintry Friday, the philosophy professor at a small college looked out at his class only to see a single student. The snow was deep, the wind was blowing, and the rest of the class just was not able to make the long, cold trek to school. Undaunted, the professor launched into the full text of the lecture he had prepared. He was determined to reward the student for his faithfulness and deliver his best lecture ever. He elaborated on each point. He quoted from multiple sources, contrasting their different approaches to the core argument. He gave stirring testimony about the marvelous accomplishments of visionaries who had followed the tenets of the philosophy he espoused. And finally, he concluded with a call to his audience, exhorting him to embrace the difficult but rewarding path he had just laid out. After speaking passionately for two hours straight, the professor was so excited he could not wait to ask the student his impression of the lecture. The student was quiet for a long time before he spoke. “Professor, I have to feed the cattle at my folks this afternoon. If there is only one steer in the barn, I’m not going to make him eat the whole bale of hay.”

I have sometimes been guilty of trying to feed my students the whole bale at once, trying to include every excruciating detail about a topic before they have gained a broad understanding. Information overload can cause cognitive indigestion. This occurs when the listener has a large amount of data without any real framework to organize and understand it. Most people tend to learn in stages, unfolding a little bit of the mystery at a time. The study of electricity is like this. We start with general description and then add ohm’s law to refine the idea. Then after the students have the hang of standard ohm’s law formulas, we add series and parallel calculations. After students can handle these we tell them that ohm’s law is not valid for most air conditioning work because of inductive and capacitive reactance. If you are really sadistic, you will then trot out the LCR calculations. There is method in our madness. If we were to drop all this on the students in the first week, most would become confused and frustrated. It is OK to leave out details and fill them in as the students gain subject maturity. In fact, for most folks it is preferable. It is far better to feel that you are making progress, than to feel that you are drowning in information. One of the ways that I know when a student is really “getting it” is when they comment that they are beginning to understand how much they don’t know. Typically, these are some of the brightest students – they are gaining enough insight to get a glimpse of the bigger picture. It is all right to try to teach your students everything you know. In fact, your goal should be for your students to learn more than you know. It just will not happen overnight. If you guide them well, it will happen and they will return to share their knowledge and success with you. There is nothing more rewarding.

Service IS What We Sell

2010-08-28T17:35:00.001-07:00

HVAC/R service technicians must master many different skills to be successful. There are the hard skills that involve manipulation and mechanical ability like electrical wiring, brazing, and refrigerant handling; there are the problem solving skills like refrigeration and electrical troubleshooting; and there are soft skills such as customer service. Service technicians must be competent in every one of these skillsets. Note that these skillsets are quite different from each other. The hard skills require mechanical ability and a good kinesthetic sense. Problem solving requires abstract thinking and the ability to take several pieces of information and form a reasonable judgment. Even if a service technician has great mechanical ability and is an accomplished problem solver, they must be able to deal with customers. Service work is primarily about customer service. Often, individuals who are mechanically gifted are not “people persons.” They would much rather rebuild a compressor than talk to the compressor’s owner. The problem is that the compressor is not who writes the checks, the owner is. So if you want to be paid, you need to learn to talk to the customers.

Increasingly, service technicians are required to make out a bill and collect payment. I consider this yet another skill set – financial. In the good old days, I would simply tell the customer that they would receive a bill. When they wanted to know how much it would be I honestly did not have a clue. I might as well have told them to write a check and leave the amount blank so I could fill it in for their convenience later on. Customers now expect to know what they owe before the technician leaves. In many cases, the company expects the technician to collect payment. To create bills and collect payment technicians must be familiar with the company’s pricing policies. Many companies use price books which list prices for specific services. The price includes all aspects of the cost - parts, labor, overhead, and profit . Technicians bill customers according to the services they deliver. The technician needs to learn how the book is organized and be comfortable looking up prices in the book. Many technicians are uncomfortable using the books, making bills, and collecting payment. Often, companies just hand the new technician the book without much training. Although every company’s price book and billing procedure are unique, most companies now require their service technicians to produce bills and collect payment.

I think every HVAC/R program should have some example pricing procedures available to their students. The point is not to tell them what to charge, but to help them prepare to make bills using pricing policies that are prevalent in your area. A vendor for a price book that is used by several contractors in our area supplied us with a sample book. The prices do not reflect any particular company and all services are not in the book. Further, SAMPLE is written prominently across every page. But this book lets us inject a dose of reality into troubleshooting. Students should not only be able to track down the cause of the problem, they should also be able to find the service required to repair the system in the price book.

One thing that many students have a hard time with is the large price discrepancy between the cost of the part being replaced and the cost of providing the service. I emphasize that the customer pays far more for the technician’s expertise and service than they do for the part. The cost of the part is almost negligible. I point out that this is true for nearly any service business. Otherwise, the company cannot make money and their technicians cannot earn a good living. They are not cheating the customer by charging a high price. They are cheating the customer if they fail to deliver complete and competent service. We are called service technicians for a reason.

Making the Connection with Schematic Diagrams

2010-08-20T16:41:00.000-07:00

Many of topics that our students struggle with the most have some level of abstraction. Reading a schematic diagram is near the top of the list. A schematic diagram is a symbolic representation of an abstraction – circuit logic. Mentally tying this symbolic representation to the physical components and wires can be a struggle for some students. This is especially true for devices like contactors and relays that are represented by multiple symbols because they have parts with different functions located in different circuits. Recently I have tried having students draw a schematic diagram of a basic packaged air conditioning system. Then I give them a pictorial diagram with drawings of components and ask them to “wire up” their schematic. Most students have a few difficulties drawing the schematic, but they usually make it past this part without too many scuff marks. The trouble comes when they have to translate the schematic diagram that they drew into “wires” on the pictorial diagram. I believe this is because students can essentially copy circuits they see in the book without understanding the details. However, details are important. Several years ago, we would put all our electrical theory up front. Students did not do any wiring until after covering all the theory. However, I noticed that many students who could draw a basic heat pump schematic diagram could not wire a toggle switch and a light. This caused me to wonder how much they really understood. Having students “wire” units on paper by drawing lines between pictures or drawings of components allows them to work out the connection between the abstract and the physical without burning up all your transformers. I am not suggesting that drawing lines to represent wires replaces wiring actual components, but it will quickly show you who has a clue and who doesn’t. You need to work some more with the folks who can’t differentiate between low voltage and line voltage circuits, or the people who want to put L1 on one side of a spst switch and L2 on the other side of the same switch. The pictorial diagrams with all the wires drawn in can look a bit messy and hard to follow. Using color coded markers helps. Better yet, use colored pencils that can be erased. Use two colors for line voltage and two more for low voltage. Have them draw in large dots where two wires are supposed to connect and little humps where two wires cross that are not supposed to connect. It does not take students long to figure out that neatness is its own reward. Loopy, hastily scribbled lines make for difficult circuit tracing and lead to confusion. I usually have a big stack of pages with the components that need to be “wired up.”

Your Job is NOT to Answer E-mail

2010-08-14T11:25:00.001-07:00

My job would be so much easier without the constant interruption from these students! It can be easy to lose your focus in the hustle and bustle of running an HVAC/R program. With the demands of documenting things like student learning outcomes, justifying the need for an expendables budget for items like copper, advising students, scheduling classes, attending faculty meetings, and answering e-mail, it sometimes seems like taking care of administrative details is your primary job. There can be a bit of a let-down when the fury momentarily subsides and there are no URGENT e-mails to answer. "Oh there are no e-mails, what do I do?” Then a student comes in, asks a question and I remember why I am there in the first place. It is important that we remember to save enough time and energy to focus on the students. All the other things are just supporting roles, not the main job. One way to keep the administrative part of teaching from completely taking over your time is to set aside a specific time for accomplishing administrative duties. One day a week I do not lecture or teach in the lab, I administer. That way I am not stealing time from the students, trying to complete reports five minutes at a time in between working with students. When you are juggling administrative functions and students at the same time it may feel like you are being productive because you are so busy, but an honest assessment of what you have accomplished afterwards can be deflating. I personally find that trying to juggle students and administrative details at the same time leads to lack of focus and poor performance on both tasks. That is not to say I don’t answer any e-mails until Friday, it just means that I know I have time to accomplish time consuming tasks on Friday. Another trick is to automate administrative tasks whenever possible. I confess that for many years I really could not understand why many of my friends liked using test banks to write quizzes and tests. I was a purist – writing all my tests from scratch so no two tests were ever the same. I would often save them in Word format, and use old tests as templates, but that was the extent of my automation. Then I became involved in writing Fundamentals of HVAC/R and everything that goes with it, including writing a bank of test questions for use with TestGen. It did not take long for me to see the advantage of using an organized test bank. I can write a good test in about five minutes by just selecting questions from the test bank. I can still write all the new questions I want, but saving them in the test-bank format means that I can retrieve them easily later on. With all the Word documents, I end up searching through lots of electronic documents looking for that gas furnace test I wrote last year. Finally, you should learn to use your tools. You expect your students to learn how to use gauges and electric meters. They have to become proficient in their use to do the job they are training to do. Similarly, all instructors should be proficient with office productivity applications like Word and Excel. If Microsoft is not your cup of tea, substitute whatever word processor and spreadsheet program you like, but mastering the word processor and spreadsheet will make your life much easier. I would certainly not try to pass myself off as an expert in either, but I do use both Word and Excel on a daily basis. Since I use them every day, learning to use them well saves me time. This requires an up-front investment of time, but it pays off almost every day.

Communicating Control Systems

2010-08-06T13:49:00.000-07:00

The standard air conditioning control system uses relay logic or an electronic representation of relay logic. Things are either off or on. The controls work something like a light switch – when the switch is on the light operates, when it is off the light is off. Thermostats are basically switches that are controlled by temperature. The thermostat closes a set of contacts to complete a circuit to a relay coil, the relay coil then closes the relay contacts to complete a circuit to a motor. When the thermostat is satisfied its contacts open, breaking the circuit to the relay coil. The relay opens its contacts, breaking the circuit to the motor. Everything works based on the presence or absence of control voltage. One advantage of this system is that it is easy to understand, and it has been the basis for HVAC/R controls for many years. However, this control system needs a separate control wire for each function. Some split system heat pumps require 12 control wires running between the indoor and outdoor section. Even with twelve wires, the range of control is still somewhat limited.

A communicating control system is more like a computer network. The system components communicate over a serial network. Each part has its own unique electronic signature or address, allowing the controller to recognize all the parts and coordinate their operation. Most residential communicating systems use four wires between all components – two for power and two for communication. It does not matter if the component is a furnace, air handler, air conditioner, heat pump, or zone control – everything uses the same four wire connection. This works because the units respond to commands sent over the communication network, not the presence or absence of control voltage. Commands for different components can be sent over the same network. Further, communication is not just one way. Communication between components allows them to know what the other components are doing and adjust accordingly. For example, Carrier’s Infinity zone control knows what the blower CFM is and what the CFM in each zone is. Better yet, it can report this to the service technician. The system airflow can be ramped up or down to match system capacity. Staged furnaces, air conditioners, and heat pumps give the system the ability to modulate system capacity and airflow as the house load requires, improving efficiency and reducing energy use. Just a few years ago Carrier was the only game in town if you wanted a residential communicating system. Some folks were not paying too much attention because these systems were only offered in high end equipment made by one equipment manufacturer. Today it seems like everyone is offering a communicating system. Equipment manufacturers advertising communicating systems now include Carrier, Bryant, Trane, American Standard, Lennox, York, Rheem, Ruud, Amana, and Goodman. I apologize in advance for leaving anyone off. The point is that communicating controls are booming. Communicating systems used to be proprietary, now there is an open standard called ClimateTalk. The ClimateTalk will encourage the development of equipment that plays nice across different brands. I don’t believe we are at the point of interoperability yet, but that day is coming. Besides the proprietary systems built exclusively for a particular brand, two major control manufacturers are producing communicating systems – Emerson and Johnson Controls. The availability of “standard” components and an open protocol means that smaller manufacturers can use communicating controls, opening the market up even more. In the very near future, every technician will need to work with communicating controls regardless of the brand equipment their company sells and services.

For more details regarding communicating control systems check out Unit 52 Heat Pump Installation, and Unit 59 Zone Control Systems in Fundamentals of HVAC/R. Many manufacturers also have some information online regarding their communicating systems, including

Carrier Infinity
Trane ComfortLink
Lennox Icomfort
Goodman ComfortNet
Rheem Comfort Control System
Emerson UltraTech
ClimateTalk Alliance ClimateTalk

Interactive PowerPoint Presentations

2010-08-02T17:36:00.000-07:00

Most PowerPoint presentations are used to as visual aids for a lecture or presentation. As such, they do not have to stand on their own. The speaker will fill in the details and keep the presentation engaging – or at least that is the plan. However, PowerPoint presentations can also be used as a self-paced leaning activity. This has the advantage of allowing the viewer to control the flow of material. If the presentation is designed for individual viewing, you can include more information in a slide, or you can narrate each slide to replace the live speaker. Try to layer the information so that it is presented a little at a time in a logical fashion, rather than all at once. For example, show a contactor with a title that names it: Contactor. Use the same picture on the next slide and add text that generally describes what it does. Then do a series of slides that label the parts: coil, contacts, L1 & L2, T1 & T2. The idea is to introduce the information a little piece at a time in a logical manner. After all the parts are located, have a series of interactive slides that ask the viewer to click on different parts.

Use shapes to make the clickable points. You can add shapes on top of a picture by gong to the “Insert” tab, clicking on “Shapes”, and clicking on a square or circle. Draw a square or circle over the area you want the viewer to click. It normally will draw a filled object. To make it transparent, click on the “Format” tab, click on “Shape Fill” and click “No Fill.” You can now see through the object, but the line is still there. You can leave the line as a general guide, or you can make it disappear as well. If you don’t want the line, click on “No Outline.” However, wait to do that until after you are finished designing the page because you won’t be able to see the object.

To make the object interactive, select the object, click on the insert tab, and click on “Action.“ A dialogue box will pop up that allows you to choose the action you want. First, you choose if the action is from a “click” or a “mouse over.” Then you can choose between a hyperlink, running a program, or running a macro. I like hyperlinks because they are relatively simple to do. The hyperlink can go to any slide in the presentation, an address on the internet, a file, or even another PowerPoint Presentation. If you know the viewer will have online access, you can hyperlink to manufacturer’s web sites to incorporate publicly available information in an organized fashion. Rather than just pointing your students to YouTube, the PowerPoint presentation can direct them to specific YouTube videos that fit in with the lesson.

PowerPoint Fast Lane

2010-07-24T15:20:00.000-07:00

Let me start by stating that I am far from a PowerPoint Guru. But even an old-school whiteboard warrior like me can learn to use PowerPoint presentations to improve instruction. PowerPoint presentations are built like an electronic slide show. I suspect that if you are younger than 30 years old you might not have ever seen an ACTUAL slide show. Suffice it to say, making a PowerPoint presentation is SOO much easier than making an actual slide show. The slide show format displays pictures in a sequence while a presenter narrates or discusses the slides. PowerPoint presentations retain this overall organization, but they allow a great deal more flexibility. It is possible to add animation, audio, video, time the appearance of different elements, and use interactive responses just to name a few. However, the most common presentation is still a series of pictures. It can take quite a while to select pictures individually, place them, and add titles. This can all be done quickly by inserting a photo album. To create a presentation quickly, follow the following steps.

Take a bunch of cool pictures with your digital camera.
Always take more than one picture of each item using different light levels and angles. It does not take much longer and will save you time in the end. You can’t always tell the quality of the picture using the small LCD screen on the camera.
Import the pictures into a folder on your computer. Make sure the folder is located where you can find it and named something appropriate – “Way Cool Pictures”
Start PowerPoint and click on “Insert” in the ribbon at the top.
Click on “Photo Album” and then choose “New Photo Album”
In the box that opens, click on the “File/Disk” button at the top left to open a file selector dialog.
Navigate to the folder containing your pictures and select the pictures you want.
You can select individually by holding down the “Ctrl” key down as you click each picture; or you can select a group by clicking on one picture, holding down the shift key, and then clicking on the last picture.
After selecting your pictures, click “Insert” at the bottom right of the dialogue box.
The next dialogue box shows a list of your pictures. You can rearrange their order or delete pictures you don’t like here.
At the bottom of this dialogue box you can choose how many pictures per slide and whether or not you want a title.
Next, choose the type of frame around the picture and any theme you want.
Finally, click “Create” at the bottom and your new presentation will be created.
You can now go back and fill in the titles for each slide. Just click where it says “Click to add title” on the slide and type in the title for that slide.

If you are using Fundamentals of HVAC/R, you can download all the supporting PowerPoint presentations at Download. As I said at the outset, what I don’t know about PowerPoint presentations would fill a book. Fortunately I have friends in the know. Gary Reecher sent me this link to Microsoft’s site Twelve Tips to Better PowerPoint Presentations. It is well worth your time. If you would like to have someone do the heavy lifting for you, you can’t do better than the presentations the Dick Wirz puts together. You can find out more about his material at

Dick & Irene Wirz

Refrigeration Training Services, LLC

6609 Briarcroft Street

Clifton, VA 20124

703-830-6004

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Do You YouTube?

2010-07-17T13:00:00.001-07:00

Electronic social networking has made it possible for people to enjoy global communication with millions of people who share common interests. HVAC/R is no exception. Take a look around the web and you can quickly find many discussion forums, web sites, and media aimed at HVAC/R technicians. You have to exercise some discipline when perusing web materials because it is easy to while away hours of time reading and viewing content on subjects that you are interested in. YouTube is especially addicting because they have figured out how to keep feeding you video clips that are related to what you are watching. If you start looking at clips of compressors, more and more compressor clips will keep coming up in the side bar for you to view. However, my discussion is not how to avoid internet addition, but how to employ internet addiction for teaching purposes. The easiest way is simply to give your students unfettered access to the web, point them to a list YouTube clips, and stand back. This approach does come with some amount of risk because everything is on YouTube. The very openness of the format which encourages sharing and communication also aids in the transmission of inaccurate or even offensive ideas. There are oscillating parts on YouTube videos that are not attached to compressors! For this reason, many schools filter or restrict online material so severely that it is not really possible to use YouTube live. Many schools block sites like YouTube entirely. If that is the case, you can still view and download the videos at home and then take them to school. This gives you control over what is seen and allows your students access to the material. Although YouTube does not provide point and click ability to download their files, many people provide sites or programs to do it. I use a free program called YouTube Downloader. It is available on CNET, a trustworthy site for downloadable computer files. I then download the files onto a jump drive to take to school.

There are literally hundreds of video clips on YouTube that are helpful in HVAC/R, but my favorites are clips that show things you can’t see elsewhere. A gentleman in Australia has several clips of compressors he has cut open. Many of them operate. Seeing the movable scroll on a scroll compressor orbit as the compressor is energized is way cool! I must admit that seeing him cutting open compressors with a grinder, sparks flying appeals to the kid in me! Before you run out and start sawing up compressors, why not take a look at what he has already done. To help you get started on your internet addiction, I have included a short list of YouTube compressor videos to whet your appetite. The titles are hyperlinked, just click on the title to go to the video.

Open Scroll 3

Off with its head

Daikin Relucance DC Swing Compressor

30 HP Carlyle Semi

Kirby Reciprocating Compressor

Managing Large Group Labs

2010-07-09T18:50:00.000-07:00

The easiest way to manage your lab is to have one lab instructor for every five students. I have actually taught lab classes where we had this ratio and it was a lot of fun. We were able to spend a lot of time with each student and we were able to do things you just can’t do with larger groups. So what if you have more like 20 students per lab instructor? It is still possible to give them a good lab experience, but a lot more planning and organizing will be required up front, and there will be things that are just not practical. One management technique is to split up large groups into smaller ones and schedule them at different times, effectively making several smaller lab classes. Of course this means you must spend more time than usual since you will be repeating the lab for each group. This may not be an option for everyone depending upon the number of instructors, students, lab equipment, and available lab time. For most of us, there will come a time when we have to work with larger groups in the lab.

A common technique is to have students work in groups. I try to avoid this if possible because it often means a couple of confident students do the work and the rest of the group watches and writes down the results. In group projects, you can see the 80/20 rule at work: 80% of the work is done by 20% of the people. However, this can be managed if you know it is going to occur. Ask every member of the group a question that requires an understanding of the process. For example, if the group is measuring the superheat on an air conditioning system you might ask different students

What is superheat?
What measurements are required?
How did you arrive at the current superheat?
What readings are necessary to use the manufacturer’s superheat charging chart?
What does the system charging chart say the superheat should be?
What does this system's superheat tell us about the system?

If they know they are going to be asked to perform a task or answer a question, they will at least pay more attention to what is going on.

Some skills are so important, every student must perform them for you individually. Lighting an oxy-acetylene torch is one example. An issue with large groups is simply the amount of equipment and tools available. Most of us would be hard pressed to come up with 15 oxyacetylene torch sets so that every student could have their own. Besides, I really do NOT WANT to have more than three rookies working torches at the same time. Once when I had a class of 18 students who needed to learn to braze, I worried about how I was going to teach all of them to handle an oxyacetylene torch safely. What I did was to demonstrate, as I always do and then ask questions to see what people remembered. We then went back over the procedure, paying particular attention to things that I felt they had missed the first time. Finally, I lined them up and had each student turn on the tanks, set the regulators, light the torch, adjust the flame, shut off the flame, and shut down the torch leaving it ready for the next student. If they hesitated, they repeated the process. I noticed that the students got progressively better, which was odd because the most confident students had stepped forward first. When I remarked to one student on how quickly and confidently he performed the task he replied “I saw it done 10 times before I had to do it.” In other words, the students waiting in line learned through the experience of their fellow students. This made me feel less guilty about having everyone wait in line to work with me. This method works well for procedures that can be demonstrated in a few minutes such as lighting torches, soldering, brazing, or installing gauges. If the students use their time wisely and pay attention to what is going on they will learn by watching others and everyone leaves with an important skill they did not have the day before.

Delivery Styles - Lecture

2010-07-03T11:25:00.000-07:00

I am sometimes asked which instructional delivery system I think is best: traditional lecture lab, self paced, or computer aided and online. Like a trick question, the answer is all of the above. Each method has strengths and weaknesses. I have used each at different times in my career and enjoyed the advantages and suffered the frustrations of each of these delivery styles. Most people are familiar with the lecture format. In fact, to many people the other formats are not really teaching. I do not agree with that sentiment, but I understand why people sometimes feel that way. I will talk today about the lecture format and cover the others in later columns.

Undoubtedly, the lecture format is efficient at disseminating information to large numbers of people. If we are honest, it also appeals to the ham in most instructors: we like to talk! I will admit that I enjoy lecturing, and I believe my students enjoy my lectures. However, I may not be the most objective judge. Lectures can be engaging with good preparation and a well developed style. However, they can also be deadly. The derisive terms “talking head” and “chalk and talk” are well deserved. Did you ever see a video that is basically a picture of someone while lecturing? Usually they are hard to sit through. After watching a few I decided that the reason the videos of my lectures were boring was that the original lectures were boring. I was talking, and talking, and talking and I am sure the students were nodding off. Remember, your job is not to just cover all the topics, it is to teach your students. A big problem with lecture is that people do not tend to retain most of the information they hear, active participation is needed to retain the information. A few ideas to increase student participation are taking notes (not a big hit with students), asking students questions, asking leading questions, regularly entertaining questions from students, or engaging them in a dialogue. I like the dialogue format. Today, I don’t tend to talk to my students as much as have a structured discussion encouraging their participation and asking them questions. Repetition is also good. If something is important, don’t just say it once, say it several times using different approaches. After you think the students know the information, ask some questions to find out.

Speaking style and delivery is important, but can vary a great deal from one person to the next. In general, you need to be interested in what you are saying. Students can hear the interest and passion in your voice. They can also hear disinterest and lethargy. You need to be interested and excited about your field. Humor works for some speakers, everyone loves to laugh. Don’t feel compelled to tell a joke, just use humor if it comes naturally. Stay away from jokes involving off color, racial, religious, or political jokes. Jokes on yourself are fairly safe and students enjoy a laugh at the instructor’s expense. Most people find stories more engaging than a recitation of facts. Having taught for many years, I have a large body of stories to draw on.

Visual aids are great for creating interest. Rather than draw a crude diagram of something on the board, pass around examples of the real thing. If you have a video projector and document camera you can zoom in on parts and show details to the whole class that are not easily visible even to someone holding the object. The table in front of where I lecture is usually a mess because it is covered in stuff I brought in from the lab to show. The ultimate visual aid was a complete transport refrigeration unit sitting in the corner of the class room when we were teaching transport refrigeration. Students disassembled the unit, brought the frame and pieces into the class room, and then reassembled the unit in the corner. When I talked about the location of parts I could actually put my hand on the part on the unit. We gave tests using sticky notes attached to components and students were required to identify components. They would come up, look at the component labeled #1, and write down its name and function. That room is now used for an Interior design class and for some reason they did not want a refer unit in the corner, so we disassembled it and took it out of the room.

Powerpoint presentations can also help, but avoid letting the powerpoint presentation BE the lecture. Nothing is more boring than hearing someone read the text of a powerpoint presentation. I remember being surprised when several students mentioned to me that another instructor’s classes were boring. This instructor had really world class powerpoints that he had developed. They were complete with movement, animation, great details, and good photos. In fact I was rather envious of them. However, the students said they started to doze off as soon as the lights were out. They were not actively participating and they tuned out. This is not to say you shouldn’t use powerpoint presentations, just remember that they are a supplement, not a replacement.

Personally I feel that the biggest weakness of traditional lecture lab is the lab component when five people are assigned to work together on something that really only requires one person. I will leave that discussion for next time.

A Father's Legacy

2010-06-20T13:45:00.001-07:00

When I was 13 years old my father started Stanfield Air Systems. He moved his family to a city he had never lived or worked in to start a brand new business in a field he knew little about. For capital, he used his life savings and a line of credit. It was not until many years later when I had my own family that I truly understood the courage it took for my parents to do this. He gave up a secure job with a major corporation that had just offered him a promotion. He was one of a class of businessmen recruited to start air conditioning dealerships. After five years, he was the only one of his class still in business. Stanfield Air Systems survived major builders declaring bankruptcy and not paying, strikes by compressor manufacturers when equipment was hard to get, and more than one economic downturn. Because of dad’s pioneering spirit, Stanfield Air Systems has frequently been in the vanguard of new or unique technology. We put in solar systems in the late 70s and water source heat pumps in the 80s. Some of the more unusual equipment we installed included Space Pack high velocity systems, Amana EG units, and Arkla Servel absorption chillers. People around Athens learned that if you wanted to do something out of the ordinary and be successful, you wanted dad’s company to do it. One thing that has stayed constant is a commitment to quality. He sold himself and his company, not any particular brand and certainly not price. His price was usually higher than the competition, but he offered services and quality not available elsewhere.

I have a brother and a sister, and we all work in the air conditioning field. My sister now runs Stanfield Air Systems and they are doing great. They remain the company people who insist on quality turn to. I am especially proud of the pictures in my book that came from Stanfield Air Systems showing what a good installation looks like. My brother is a top service technician – for the competition. He has customers that call and ask for him by name because he has the same commitment to quality service and honesty as our father. And I teach air conditioning at Athens Technical College. I am proud to say that many of the technicians at Stanfield Air Systems graduated from Athens Tech. For that matter, so did many of the technicians at competing companies. In Athens Georgia, if someone comes to your house to install or service heating and air conditioning equipment, there is a pretty good chance that they are a Stanfield, work for a Stanfield, or were taught by a Stanfield. My father’s legacy includes a legion of air conditioning professionals and three children who are proud to call him dad. I know my recent success started in 1968 when a courageous entrepreneur put everything on the line to start a new company in a new town. Happy father’s day dad!

A Father's Legacy

2010-06-20T13:45:00.000-07:00

Be a Problem solver

2010-06-18T14:03:00.000-07:00

Have you ever known someone that excels in finding the cloud behind the silver lining? Some people have a knack for finding the negative to any set of circumstances. Sometimes students can get the impression that a service technician’s job is to find problems. But in truth, the technician’s job is to solve problems. Yes, you have to identify a problem to solve it, but solving the problem is the goal. Customers and employers are more impressed by people that find solutions than people that find problems. Most people already have more than enough problems, so the last person they want around is someone who generates more problems than solutions. On the other hand, people that excel in finding solutions are a joy to have around. Encourage your students to offer solutions to the problems they find. They need to become practiced in providing solutions, not just identifying problems. This can sometimes be a matter of attitude. Rather than finding reasons why something cannot be accomplished, look for ways to overcome the barriers to get the job done. This attitude should start with the way you interact with your students. Make sure to recognize what they do correctly, and not simply point out their errors. Of course you need to correct their errors, but it should be done constructively, not destructively. Always offer a better way when correcting students who are struggling. The student who is trying to glob on solder that is balling up and falling off really does not have to be told that what he is doing is not working; he can see it for himself. What he needs is someone to offer a better way. Students who gain skills after struggling at first appreciate the accomplishment more. You can teach more than any particular skill when you help a student overcome a learning barrier, you teach them how to be a problem solver.

Understanding Relays and Contactors

2010-06-10T16:29:00.000-07:00

I promised last week to reveal my secret for teaching relays. I know I sound like a broken record, but the first step is making sure that the students have the necessary electrical foundation knowledge. Before introducing relays and contactors, students must clearly understand circuits, loads, and switches. A relay is essentially an electrically operated switch. A contactor is really just a bigger relay. The key to understanding relay operation is realizing that a relay is actually two electrical devices: a set of contacts and a coil. The contacts are a switch. They are wired in circuits exactly like switches and they behave like switches because they are switches. Relay coils are loads; specifically, solenoids. They wire in circuits like a solenoid and they behave like solenoids because they are solenoids. The purpose of the relay coil is to operate the relay contacts. Energizing or de-energizing the relay coil makes the contacts open or close, but the coil and contacts are almost always in separate circuits. This is difficult for many students to understand. What they see is a box with a lot of electrical connections. To demonstrate how a relay works I ask the student to wire a toggle switch to control a light. Then I ask them to wire another circuit to a relay with a 120 volt coil the same way, with a toggle switch controlling the relay coil. Make sure and reinforce the idea that the coil is a load. The student should operate the circuit and hear the relay click when the switch is closed. Have the student check the continuity across the contacts with the coil de-energized, then have them operate the relay coil and check the continuity again. If you are using a relay with both normally open and normally closed contacts they should check both. Now have the student combine the circuit to the light they wired earlier with the relay by replacing the toggle switch controlling the light with the relay contacts. This illustrates that the contacts are just a switch. Now have the student operate the relay to see it control the light. Next, mention that the coil and contacts do not have to be the same voltage. Have the student wire a toggle switch and a 24 volt transformer to control a 24 volt relay coil. Then have them use the relay contacts to control a 120 volt light. If you want to extend the HVAC/R component analogy you can replace the toggle switch with a thermostat, explaining that a thermostat is simply a switch. Before leaving the exercise, find a schematic diagram and show the circuit with the relay coil and the circuit with the relay contacts to illustrate that they are in separate circuits. You can point out that the labeling identifies which relay contacts are controlled by which relay coils. Figure 32-23 in Fundamentals of HVAC/R shows a simple diagram with a 24 volt contactor controlling a compressor. The figure shows that the coil in the 24 volt circuit is controlling the contacts in the 230 volt circuit. Building the circuits to the relay in steps helps students understand how relays operate by relating the relay coil and the relay contacts to components the student already understands.

There are many resources for teaching relays and contactors in Fundamentals of HVAC/R. Unit 29 contains good discussion and illustrations of how relays operate in 29.7 Relays and Contactors. Contactors are discussed and illustrated in 32.16 Contactors in Unit 32. Diagrams using relay and contactor circuits are discussed extensively throughout Unit 33.

Teaching Ladder Diagrams

2010-06-04T15:29:00.000-07:00

Reading electrical diagrams is a crucial skill that HVAC/R students must master. That is why all HVAC/R curriculums spend a lot of time discussing how to read electrical diagrams. Many students struggle with this even though every HVAC/R instructor I have ever met emphasizes diagrams. I believe this is because students must learn several pieces of information and then weave them all together in order to truly understand electrical diagrams. You really can’t understand diagrams if you don’t understand the basic function and operation of standard electrical components. Learning symbols for components that you don’t understand is like memorizing words in a foreign language without knowing what they mean. You still can’t read. Understanding basic circuits is also a must. Students should be able to construct basic circuits consisting of loads and switches. Finally, they must have a good concept of how the system they are working on heats or cools. If all this is in place they usually will have no problem learning how to read electrical diagrams. I find that students who are the weakest with diagrams are usually also weak in one or more of these foundation areas. After all, a diagram is simply a representation of a collection of circuits that are made up of electrical components. You really can’t understand an abstract representation if you don’t understand the actual component that you can see and touch. So we start by having students build basic circuits with switches and lights in order to learn how loads and switches work in a basic circuit. Loads should have a voltage drop when current passes through them, switches should not. Then we introduce components and relate them to either loads or switches. So thermostats are switches while motors are loads. Introduce symbols and have students draw symbols for selected components. Then have them identify components on a unit using the unit diagram. The most difficult components for students to grasp are usually contactors and relays. Understanding relays is a big stumbling point for many students. I have a method for teaching relays, but I will save that for another article. Just know that there is no use trying to explain a ladder diagram that contains 24 volt control relays to someone that does not understand how relays work. After explaining basic ladder diagrams and showing several examples ask the students to draw a simple diagram of a packages air conditioning unit without looking at an example. You don’t want a copy of the book; you want to see how much they understand. There will be lots of weeping and gnashing of teeth. Students will complain that they are not artists and that drawing diagrams is not necessary to service systems. However, you will find out quickly how much they understand about circuits, components, and diagrams. People that understand diagrams can draw them. Be patient, suggest corrections, and have them revise their diagrams until they have something that will work. This typically takes several revisions for many students. Finally, have them wire the circuit that they drew using the actual components as much as possible. For safety we have a simple rule: the instructor has to check the circuit before it is energized. The pride the students get from seeing their circuit operate will offset the anguish they experienced getting there. Gradually add more complex circuits – two stage cooling, cooling and heating, heat pumps, or whatever makes sense for your area. After the students have a good command of ladder diagrams you can start discussing the many variations they will see in different manufacturer’s diagrams. There are as many variations as there are manufacturers, adding to the difficulty for aspiring technicians.

Diagrams are discussed extensively in Fundamentals of HVAC/R in units 31 Electrical Components and Wiring Diagrams, 32 Controls, and 33 Control Circuits and Diagrams. There are some great exercises in MyHVACLab to help students learn electrical diagrams including an interactive electrical symbol recognition activity and a virtual wiring exercise that aligns a ladder diagram to the actual components as they are wired.

Problem Solving

2010-05-29T05:53:00.000-07:00

HVAC/R Service is about practical problem solving. All the tools, technology, training, and literature are just there to help us identify and solve problems. The primary skill that any service tech needs is problem solving. The most important tool at your disposal is your mind. I am frequently asked why we make students do BTU calculations of ice turning to steam, series parallel ohms law problems, gas law calculations, or any host of other primarily mental exercises that nearly all HVAC/R students must suffer through. Usually, the students asking are doing the most suffering. Although I can justify all of the above as an endeavor to garner a deeper understanding of the principles which make HVAC/R systems work, I usually tell them that you can’t become a champion weight lifter by lifting marshmallows. Service techs are not paid to connect gauges or take voltage readings, they are paid to solve problems. Obviously techs need to be familiar with all the tools at their disposal, but we should never overlook the fact that their primary tool sits on their shoulders. I am afraid the current focus on standardized testing throughout our educational system has not prepared our students for practical problem solving. Rather, they are used to selecting the best solution from a very limited set of answers. My prescription? Lots of work that requires students to recognize and define the problem, systematically find the cause, and offer a solution. Assign work that requires students to provide written answers. Ask questions whose answers have not been explicitly stated, but require students to put two pieces of information together. If you get an answer that is way off base, try and ask leading questions to help the student work their way through a solution to the problem. The exact answer is not as important as the process. Encouraging students to use their minds to solve problems is crucial. The shop is a great place to work on problem solving because real life problems are never as simple as a, b, c or d. But don’t accept “the part is bad” as an answer. The student should be able to explain what the unit is doing wrong, what is the cause, how they determined the cause of the problem, and what their proposed solution is. Truth be told, I believe this approach could work in a lot of fields besides HVAC/R. The leaders in any field are always people who have recognized and defined problems and then devised solutions.

Teaching Capacitive Reactance

2010-05-21T19:25:00.000-07:00

A capacitor is basically an electrical spring. It stores an electrical charge when the voltage increases, and it releases that electrical charge when the voltage starts to drop. Capacitors are used smooth out the output of DC power supplies. When a capacitor is connected in an AC circuit it alternately charges and discharges with the AC current. This has the effect of causing voltage to peak after the current peaks. Note that this is exactly the opposite of inductive reactance which causes current to peak after the voltage peaks. Adding a capacitor in series with an inductive load offsets the inductive reactance so that the voltage and current peak together. Capacitors are used with PSC motors to improve their efficiency by offsetting the inductive reactance of the motor windings. This is why PSC motors became the standard motor for compressors and fans. Several years ago I had a furnace with a shaded pole indoor blower motor. When it died, I decided to replace it with a similar size PSC motor. The replacement PSC blower motor was slightly larger in horsepower than the original shaded pole motor, but drew only half as many amps while operating. Of course today PSC motors are being replaced with brushless DC, or ECM motors for efficiency savings that are equally dramatic.

You can do a demonstration of the effects of inductive and capacitive reactance by wiring a 60 watt light, a 120 volt 10 watt unit bearing shaded pole motor, and a 10 MFD run capacitor in series to a 120 volt power source. Wire a switch in parallel to the shaded pole motor and another switch in parallel with the capacitor. The switches will allow you to take the motor or capacitor out of the circuit by simply bypassing them. Ideally, you want to use an oscilloscope to show the source voltage and the voltage across the light. The light will remain in phase with the circuit current since the light is a resistive load. The phase relationship between the source voltage and the voltage across the light will show the relationship between voltage and current. Operating the switches will show the effects of inductive reactance, capacitive reactance, and the combination of the two. Even without an oscilloscope you can show that the voltage across the three devices adds up to more than the applied voltage. This shows why run capacitors must be rated for a higher voltage than the voltage to the unit.

I did a powerpoint presentation for the National HVACR Educators & Trainers Workshop this past March that includes an interactive virtual lab to show inductive and capacitive reactance. You can download the presentation at the HVAC Excellence web site. It is listed in the free downloads as "Practical Labs." Students can click on the switches to control them and see the results. For more ideas on teaching alternating current fundamentals check out Unit 29 Electrical Power and Circuits in Fundamentals of HVAC/R.

Dry Out!

2010-05-15T05:56:00.000-07:00

Its spring, the weather is warming up, flowers are blooming, and our thoughts turn to dehumidification. In humid climates like the southeast, removing humidity from the air in warm weather is just is just as important to comfort as reducing its temperature. Being warm blooded, our body normally produces more heat than it needs and then regulates our temperature using different cooling mechanisms. The primary cooling mechanism is evaporation of perspiration from our skin. Dry air makes us feel cooler because it accelerates the evaporation from our skin. Humid air makes us feel warmer because the evaporation process is slowed down. Dehumidification can be the difference between being comfortable and being uncomfortable at 78°F. Dehumidification can save energy by reducing the amount of sensible cooling required for comfort. Many people with oversized air conditioning systems essentially over cool their house to be comfortable because their systems do not run long enough in mild weather to reduce humidity, so they do not feel comfortable until they reach temperatures of 70°F in their house. It takes several minutes for most air conditioning coils to get cold enough to sweat. An over sized system will often satisfy the thermostat and shut off shortly after the coil reaches dew pont. A properly sized air conditioning system will run longer, allowing longer operation with an evaporator operating below dew point and removing more water from the air. Systems with ECM blowers and thermidistat controllers have a special dehumidification mode that reduces system airflow for dehumidification. This increases the latent system capacity and decreases its sensible capacity. Two stage cooling systems can help by allowing longer system operation at moderate loads. All of these are a big improvement over the typical oversized single capacity system with a PSC blower. However, an air conditioner is still not a dehumidifier.

If you are really serious about dehumidification you need a dehumidifier. In a nutshell, a dehumidifier is an air conditioner with a single blower that moves air first over the evaporator, and then over the condenser. The air first passes over the evaporator where it is cooled to dew point to remove water, and then the same air passes over the condenser where it is reheated to a temperature slightly above its original temperature. If you have a basement in the southeast you NEED a dehumidifier. My basement stays below 80°F all the time without air conditioning, but it feels warm without my dehumidifier operating. In the past most dehumidifiers have been small console types that are noisy, inconvenient, and typically undersized. Several companies now offer whole house dehumidifiers that can be integrated into a complete comfort system for your house. They have enough capacity for a house, are far quieter, and do not require you to empty a bucket twice a day. Therma-Stor has a good short animation on why basements have high a relative humidity and how a dehumidifier addresses this problem. You will find other articles on their website which help address specific dehumidifier applications. They also have a psychrometric chart in a round format that looks like a ductulator that are great for teaching psychrometrics. To read more about the effect of humidity on comfort, check out Unit 61 Fundamentals of Psychrometrics in Fundamentals of HVAC/R. To download an interactive pschrometric chart for free, go to HandsDown Software.

Free RSES Jounal for Students

2010-05-11T19:03:00.000-07:00

I truly believe that one of the best career decisions anyone can make is to choose something they love. After all, most of us are going to spend the majority of our conscious lifetimes at work. So if you hate your work, your life will be miserable. By contrast, if you enjoy your work, your life will be more fulfilling and enjoyable. However, young people often have not experienced enough of the world to really know what they will like. Unless they grow up in a family that works in the HVAC/R field, most teenagers really know very little about it. We should be cultivating a love of the HVAC/R field. One way is to expose your students to the wide array of careers in the HVAC/R field through professional journals. I bring in my RSES Journals to school and strategically place them around the class and lab for the students to pick up and read. OK, so maybe I leave them laying around – the effect is that students do read them. They will ask me about articles they read and are interested in. Many students use them as resources in other classes. Students have used RSES Journals for research articles and even for speech class. One student discovered that he could stand up and give an extemporaneous speech on air conditioning anytime based on RSES articles he read. After a few speeches on the refrigeration cycle, scroll compressors, and heat pumps the teacher told him the next speech could not be on air conditioning. She later told me that she never met anyone before who loved his field of study so much. That should be our goal – to instill respect for the craft and pride in learning and practicing it. RSES would like to help us out. They are offering FREE one year subscriptions to HVAC/R students. To get their free subscription they need to go to the RSES website http://www.rses.org/studentjournal.aspx The good folks at RSES did stress that this offer is for students only.

I think getting the RSES Journal for free is a great start at getting a whole new generation of HVAC/R technicians interested in a great organization and a rewarding career. Right after getting all your students signed up for a free RSES Journal subscription, consider thanking RSES by joining JOIN RSES. If you are already a member, thanks!

Flooded Equipment

2010-05-02T19:54:00.000-07:00

Large portions of the country are experiencing flooding from unusually large amounts of rain falling in a short period of time. Areas that have experienced flooding typically have a big cleanup job and lots of rebuilding ahead. Make sure your students know to be careful when working on equipment that may have been flooded. Even after drying out, the corrosion and debris left behind can make the controls and motors inoperable. Worse, they can be dangerous. Safety controls that have been under water cannot be relied on to work. Silt and debris can create potential shorts. Another concern is for the health of the building occupants. Floodwaters contain all types of things that you really don’t want in your air conditioning system: chemicals, gasoline, dead animals, and sewage to name a few. Coils , equipment cabinets, and insulation all will retain some of these undesirable things even after the water has receded. Technicians may be asked to repair flood damaged equipment, but in most cases the proper repair is more costly than replacing the equipment. It is hard to tell someone who has just lost most of their possessions that you cannot fix their flood damaged equipment, but that is exactly what you should do. Then there is the matter of ductwork: obviously a good place to catch things. Again, cleaning may not really be practical. A danger to technicians is the muck they will often be working in. They will be walking, crouching, crawling, sitting, and laying on this muck when they go in the house to look at the equipment. Again, this is not just mud. This is a combination of nasty stuff that is definitely hazardous to your health. For more information on flood damaged equipment check out the AHRI page on flooded equipment.

Promote Active Listening With Questions

2010-04-25T16:52:00.000-07:00

I believe that what the students do is just as important as what the teacher does. One of the big problems with traditional lecture is that most of the students are doing very little, the teacher is doing all the work. The teacher talks and the students listen. In the days before whiteboards and powerpoint this was often referred to as “chalk and talk.” I must confess that I can slip into this mode if I am not careful. Delivering a well organized lecture and writing notes as you go is not bad, but keep in mind that just because YOU SAID IT does not mean that the STUDENTS LEARNED IT! It is important to use delivery techniques that keep the students engaged. One simple technique is to ask questions. Three types of questions I use are volunteer responses, shout outs, and directed questions. Note: these are my own labels. Other folks probably have their own descriptive labels for these common methods.

I often open a topic or discussion with volunteer responses. This gives me an idea of what my students know and opens a discussion on the topic in a relatively low stress way because students are not put on the spot. Students that have done their homework or already have knowledge in the topic are the most likely to respond. Volunteer responses are probably the most often used in many class rooms. Two potential hazards of volunteer responses are that the same students tend to do all the answering, and the answers you receive can be wrong. Wrong answers are OK, just try and steer the class in the correct direction without embarrassing the student that offered the incorrect answer. If people are shot down when responding, the responses will stop.

Shout outs (my term) are questions directed at the audience in general where the answer you expect is fairly obvious and several people are likely to shout out the answer. These work to reinforce material, review main points, and provide you with feedback before you go on to another topic. I just have the class finish my sentence. For example, after discussing the states of matter and the properties of each state you might say “So, the three states of matter are … and the class will respond “solid, liquid, and gas.” Then follow with some more specific questions like “The state which has both a definite shape and volume is...”

Both volunteer responses and shout outs suffer from a common flaw: they allow a small core of dominant students to do all the answering while less confident students hide. Directed questions ask a specific student a detailed and specific question. This can be done using homework questions. The idea is to make sure everyone has to answer at least one question. I had a professor in college that was great at this. He would ask a few questions over homework or the previous day’s lecture to start each class. He would ask the question before calling the name of the person who was required to answer. This kept all of us listening to the questions and the answers because you did not know when you would be required to answer. I can tell you this technique is effective at getting lazy students to study the material before class – it certainly worked on me! However, it does also create a fair amount of stress. I use directed questions about once a week when we go over homework. Everyone knows they will be embarrassed if they show up for class without having done their homework. I reduce the stress level by going around the room in order, so students have a good idea when their time will come.

The simple act of asking questions and requiring students to do more than sit quietly improves retention of the material. After all, the goal is not for you to say everything the student needs to know, it is for the students to learn it.

Manual J 8th Edition

2010-04-18T17:36:00.000-07:00

Many industry professionals that were familiar with Manual J7 find Manual J8 hard to navigate. The increased amount of information, detail, and forms discourages even seasoned pros who are used to the 7^th edition. Similarly, I have found that students are often intimidated and confused by the level of detail and the wide variety of forms they must learn in Manual J8. I try to make it more manageable by only discussing the averaging method and keeping the first calculations simple. Stay away from peak loads and zoning until the students have got a good handle on a straight forward load study. Also, I discuss the difference between the way heat loss and heat gain are handled. Heat loss HTMs (heat transfer multipliers) are all calculated using the temperature difference between the outside and inside design temperatures. Heat gain HTMs must also take heat storage and climate variation into account.

The most obvious difference between the 7^th and 8^th editions is how HTMs (heat transfer multipliers) are determined. The seventh edition provides tables that have basically taken the U value and multiplied it time a range of temperature differentials to produce a table of HTM factors. This saves the user from calculating the HTM themselves. The 8^th edition just gives the U values and leaves it to the user to multiply the temperature difference times the U value to get the HTM. For heat loss this is a very straight forward process. For heat gain it becomes more complicated because the temperature difference is usually not simply the difference between the outside and inside temperatures. Thermal storage of different materials and climate variations both affect the cooling temperature difference. Tables in the 8^th edition show both the U value of the material and the effective cooling temperature difference, abbreviated CTD. These can become confusing because they are arranged differently for different constructions and different building components. I find that if people understand some of the underlying reasoning they can do a better job managing the details. Explain to your students why the cooling temperature difference is different for each construction and material. Attic space and ceilings are a good example. Everyone has experienced how hot an attic can get in the summer. Clearly, the temperature difference across the ceiling is greater than the difference between the inside and outside temperatures. This is due to thermal storage in the attic. But this effect is not the same all across the country. Areas that do not have a wide variation in temperature store more heat, while areas with a wide temperature swing through the day store less and have an opportunity to release some of the stored heat. The low, medium, and high daily ranges found in the weather data are used to help determine the cooling temperature difference for most materials. Low daily range climates have higher CTDs because there is not much difference between the high temperature and the low temperature of the day: they get hot and stay hot. High daily range climates have lower CTDs because there is a big difference between the high temperature and the low temperature of the day: they get hot during the day and cool off at night. The combination of material heat storage and daily temperature variations makes cooling temperature differences complex. Once students understand the why, it is time to dig in and learn the how. There is really no substitute for working through several examples on each table. You can do worksheets for students to calculate heat transfer multipliers until they are comfortable. Then let them try an entire house, starting with a basic house.

ACCA has an excel file on their website that helps you perform a Manual J8 calculation. It does not replace Mnual J, but it does make using it much easier. The file is called a Manual J Speed-Sheet and is available at http://www.acca.org/speedsheet/ Another resource is my book.

Fundamentals of HVAC/R walks students through a simple house, filling in the Manual J 8^th edition form one step at a time in Unit 64 Residential Load Calculations. Remember, teaching your students how to do a proper heat load study is the first step in correct system sizing and application. Correctly sized and applied systems operate more efficiently saving energy and money. They are green two ways.

Why Teach Manual J?

2010-04-08T19:00:00.000-07:00

ACCA’s manual J has been the gold standard for residential heat load calculations for many years. The latest edition, Manual J8, is frightening to students in both its size and cost. Many people ask why we teach Manual J calculations when everyone does load studies using computer software, especially after they get a look at the size of Manual J8. Others think that the sheer volume and complexity of Manual J8 makes a good argument for 600 square feet a ton ball park guesses. However, using the same logic you might ask why anyone bothers to learn their multiplication tables when they are always going to be using calculators and spreadsheets to do their calculations. I believe that understanding the underlying process is important to intelligently using the available tools. During a sale where items were being priced at 80% of their original price a clerk insisted that 80% of $120 was $150. They simply could not grasp the obvious; 80% of something could not possibly be more than the original amount. Their proof that they were correct was the fact that the answer was arrived at on a calculator, therefore it could not possibly be in error. Of course they had divided by 0.8 instead of multiplying, arriving at $150 instead of $96. The clerk’s lack of understanding of percentages and total reliance on technology had produced a ridiculous result that they were unable to recognize. Similarly, performing load studies using computer software by just dropping in numbers into a program provides many opportunities for error. If you don’t understand the process you may not recognize a ridiculous answer. Since equipment selection and duct sizing both rely heavily on the load study, the cost of a mistake is multiplied. One way to make Manual J8 more approachable is to use Manual J8 Abridged. It is more the size of previous Manual J editions and costs about half of the full J8 edition. All versions prior to Manual J8 used the averaging method. The eighth edition added peak load calculations that are similar to commercial calculations. The eighth edition also added factors for a plethora of unusual construction types and nearly 40 pages on duct loss and gain. The abridged version achieves is size reduction by only doing averaged calculations, removing factors for some of the more esoteric constructions, and drastically reducing the duct loss section. These things are not missed when teaching people to do their first load calculations.

One way to reduce the cost of Manual J to the students is to have your school join ACCA for $250 a year. If your school joins ACCA the students can buy Manual J8Abridged for $50 instead of $72. Another way is to have the school buy several copies and keep them in the library for student use.

Fundamentals of HVAC/R devotes an entire unit for load calculations using Manual J8. It takes the student step by step through a simple house, showing how the worksheet is filled out as you go. It was written to work with the full eighth edition, but also works well with the abridged version.

Sure, some folks still use 600 square feet per ton. The same folks do the duct system using the two sixes to an eight rule so they don’t have to do any duct calculations. When they go to charge the unit, they just add gas until the suction pressure is 70 psig. Many of the systems installed this way kinda sorta work. Trouble is – kinda sorta just ain’t good enough any more.

Keep the Discussion on Track

2010-03-26T19:18:00.000-07:00

I attended the 2010 HVACR & Plumbing Instructor Workshop at the National Conference Center in Landsdowne, VA this past week. This past couple of weeks has been both tiring and rewarding. I often pick up ideas and teaching tips just by watching other people work. I went to see Wes Davis of ACCA discuss system efficiency and picked up a simple and effective idea for handling questions that could possibly sidetrack the discussion. I am particularly bad about exploring questions and ideas that students pose during my lectures because my lectures are often more discussions than lectures. However, if the discussion gets too far away from the outline, you run the risk of missing important points and losing most of your audience while you are engaging in exploratory oratory. Don’t get me wrong, I believe you should encourage questions. However, it is important to also keep the discussion moving forward in an organized and logical manner. Wes had a large flip chart with the title Parking Lot at the top. Whenever a question came up that did not fit well into the flow of the lecture, he wrote it down in the parking lot. The idea is to acknowledge the question and come back to it, while avoiding a possibly distracting trip down a side alley of thought. I noticed that many of the parking lot questions were eventually answered later on in his presentation. He addressed the ones that were left at the end, and this discussion created more questions and discussion. Putting questions in the parking lot allowed the flow of the presentation to continue while still encouraging questions. Actually writing the questions down insured they would be addressed and showed that he was not just dismissing the questions. Then when the questions were addressed it seemed to get the group’s juices flowing and created lively discussion. There were many good power point presentations that will be put up on the CARE website. You have to be a member of CARE to see many of them, but one good power point presentation is worth the $25 cost of joining CARE. I would recommend that you join CARE and go to the resources they have on their site for their members. The CARE website is http://www.carehvacr.org/