Cool Toys for HVAC/R Instructors!

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

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!

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

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

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

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?

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.