New Year Challenge

The coming year promises to be a busy one for anyone teaching HVAC/R. Enrollments are up at schools across the country as people turn to trade schools and technical colleges to increase their employability and earning potential. This is happening at a time when many schools are experiencing budget cuts due to the lagging economy. Other challenges are posed by significant industry changes starting in January due to the elimination of HCFC 22 in new equipment. The year ahead is starting to look like a difficult year. But these events also have a significant potential upside. First, business is booming. The HVAC/R industry has been wishing for years that more people would choose to enter this field because the qualified labor pool keeps shrinking while the need continues to grow. We now have a unique opportunity to help the HVAC/R industry and technical education as well. If we can turn this bumper crop of students into a bumper crop of trained HVAC/R personnel we can make a sizeable dent in the technician deficit and prove the value of the technical education system at the same time. The graduates of Air Conditioning Programs all over the country will be entering the job market just as significant new technologies are being adopted. Technicians who understand how to handle the newer refrigerants, who can work with the increasingly sophisticated control systems, and who read and follow manufacturer’s instructions and technical bulletins will quickly establish themselves as industry leaders. They are the future of both the HVAC/R industry and technical education.

I can hear you saying “how am I supposed to teach more students and adopt newer technology while my budget is being cut?” I will readily admit that is a big challenge, but it is not insurmountable. First, choose course materials that provide a lot of bang for the buck. I believe that Fundamentals of HVAC/R provides an unmatched value for HVAC/R course materials. One text can be used throughout the program, saving on textbook costs. The text is provided with many free additional resources including a powerpoint presentation for each unit in the book, a large test bank of questions, a test generation and management application, and an instructor’s guide that provides a detailed lesson plan for every unit in the book including suggested class activities. However, the really unique feature is the complete turnkey online module, MyHVACLab. Online course delivery and management is the newest buzz in technical education. MyHVACLab is not simply a set of questions that can be imported into a course you are constructing with Blackboard or Angel, it is an already constructed course complete with questions, interactive learning activities, animations, powerpoint presentations, and troubleshooting simulation software. It is ready to go out of the box. However, you are not confined to the default course, you can still build or customize courses any way you want. But with MyHVACLab, you can start with a complete course. To learn more about MyHVACLab click on Fundamentals of HVAC/R.

The payoff for adopting on-line course material is more than the fact that it can simplify your life. Having on-line course material impresses administrators. Your chance of successfully competing for scarce financial resources increases when you give administrators something they can show off. People invest in success. If you show success integrating online technology with your curriculum resources will follow.

Another way to stretch your training dollars is to utilize free online materials available from equipment manufacturers. It takes an investment of time to find them, but many OEM parts manufacturers, equipment manufacturers, and even wholesalers have articles, animations, powerpoints, and educational material available online to anyone who wants to download it. This material does often come in the form of product promotion, but it is typically professionally produced, technically accurate, and free.

Talk to local distributors, wholesalers, and contractors about equipment donations. Often they can get more by way of tax writeoff for a scratch and dent special or an old model by donating it to you than if they sold it. All manufacturers send equipment to third party testing organizations for testing. Afterwards, this equipment cannot be sold as new even though it only operated for a few hours. Again they can probably do better financially by donating the equipment.

Make your own trainers. Who knows better what you need to train with than you? You already have or can get the parts, and you have slave labor (students). The students building the trainers receive great experience doing things you might not be able to have all students do. Future students receive the benefit of using a trainer designed by the person who knows the most about what your students need – you.

This all boils down to one thing: you are being presented with both the challenge and opportunity to work harder than you have ever worked before. By accepting the challenge you have the power to make a positive impact on the lives of your students and on the industry as a whole.

The Gift of Teaching

Teaching is an exchange of gifts. Teachers share experience, knowledge, and skills with their students and students share their success with their teachers. One of the most rewarding aspects of teaching is sharing in the pride and joy students feel when they accomplish the goals they have set for themselves. Students are eager to return and show you how successful they have been. I believe most teachers take more pride in what their student’s accomplishments than their own. Because you have an opportunity to participate in the success of many students, your investment in them is returned with compound interest. You will accomplish far more through the compound effort of your students than you could ever do by yourself. One of the most rewarding experiences is watching someone transform their lives and being there to help along the way.

In Georgia adult education is tied to the Technical College System. We help people who did not graduate from high school study for and obtain their GED. The state offers students who earn their GED a $500 scholarship to attend a Technical College program. Once they are accepted in a technical diploma program like Air Conditioning Technology, most Georgia residents qualify for a HOPE Grant which pays their tuition and fees. Several years ago I had a student take advantage of this series of incentives. He is a single parent who was earning a living cleaning a local McDonalds at night. He paid a babysitter to stay with his daughter while he worked at night. Although he was very bright, motivated and a hard worker, he lacked even a high school diploma. He came to Athens Tech and earned his GED. The state tempted him with the $500 scholarship and he started the Air Conditioning Technology program. So now he was a single parent working at night and attending school during the day. However, because of his initiative he quickly began to put his investment in school to work by fixing things in the restaurant at night after cleaning up. His employers noticed. He was offered a job in maintenance during the day. He continued to do well. Now he is head over all the facilities maintenance at all the McDonalds in our area, drives a company truck, and earns an impressive salary. He comes by school every now and then and I sometimes see him when I visit the McDonalds down the road from school. And his daughter, the little girl who he had to pay a baby sitter to watch while he scrubbed floors at night, well she is now also an Athens Tech alum. Sometimes we get it right. Merry Christmas to all of you. In the new year I hope you are busy sowing the seeds of success and watching them flourish.

All I Want for Christmas is a Final Rule

The EPA has released a new final ruling on HCFC reduction for Christmas! I know you are probably thinking that is not much of a Christmas present, but it really is. First, the HCFC allocations were due to expire, so without a new ruling spelling out HCFC allocations, all R-22 manufacturing and importing would have ceased January 1, 2010. A new ruling setting allocations of HCFCs has been released, fixing this potential train wreck. You can download a copy of the ruling and read all the details on the EPA website

Next, the details of exactly when you may and may not install “new” equipment which uses HCFC refrigerant have been clarified. You may recall that last December the EPA shocked our industry by announcing that they considered systems which are field installed and charged to be “manufactured” when the refrigeration system was complete and the final charge added. For split systems, this would be when the system is installed. Most people in our industry were well aware of the manufacturing cutoff of January 1, 2010, but we assumed the more common definition of manufacturing date: when the equipment is made in the factory. The EPA is sticking with their definition of manufacturing, but that does not mean all R-22 inventory becomes rubbish on January 1, 2010. Packaged equipment like window units, PTACS, and packaged air conditioning equipment can all be legally sold and installed as new provided it is manufactured (in the factory) prior to January 1, 2010. You are allowed to sell and install pre-charged R-22 component parts made before January 1, 2010 to replace parts in existing systems. So you may swap out condensing units, evaporator coils, or even both in an existing system. Replacing both the condensing unit and evaporator coil on an existing system is legal. Another interesting twist is that manufacturers may ship component system parts with a nitrogen holding charge instead of refrigerant. These “dry” components can then legally be assembled into a new system provided the system is then charged with reclaimed refrigerant and not virgin refrigerant. The impact of these regulations will be minimized by the fact that most manufacturers reduced or eliminated their R-22 equipment manufacturing the past few years. Contractors have also widely accepted R-410A and few still install new R-22 systems now. R-22 production will be reduced to 41.9% of the baseline production, but that will probably be enough. With no manufacturers using it and no new systems being installed, I believe that R-22 will still be available for servicing existing systems.

I do not believe replacing an existing R-22 system with a new R-22 system is really in the customer’s best interest. Why would someone want a system that uses a refrigerant which is scheduled for extinction? Also, all new high efficiency equipment uses HFC refrigerant, not R-22. We still need R-22 equipment in schools simply because our students need to know how to work on it. You cannot assume that every call will be on a system with the latest technology. In fact, you can almost assume the opposite. Our students will continue to see R-22, so we need to teach it. However, we need to teach toward the future and not stay stuck in the past. Your lab should have many pieces of equipment with HFC refrigerant, like R-410A. You should have recovery equipment and gauges manufactured specifically for R-410A. Your texts, manufacturer’s literature, and technical literature should all support the newer refrigerants. One of our focuses in Fundamentals of HVAC/R is support for new refrigerants such as R-410A. The newer refrigerants are not only covered in the refrigerants section, but throughout the book with detailed examples using R-410A. You can learn more about Fundamentals of HVAC/R at Pearson’s site.

Oh the Weather Outside is Frightful!

Oh the weather outside is frightful, and the furnace is so delightful. But since it dries out the air so, humidify, humidify, humidify! I took a few liberties with the popular holiday tune “Let It Snow” to point out how important humidification is to maintaining comfort. Being warm blooded, our bodies normally produce more heat than they need and then regulate 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. Heated air is drier because the air volume increases, creating more places for water molecules to fit. In the winter, the cold outside air simply cannot hold very much moisture because of its decreased volume. Take it in the house, heat it up, and it expands in volume and decreases in relative humidity. It still has the same amount of specific humidity in grains, but its relative humidity is much lower because it can now hold more water. Many people overheat their homes to compensate. Have you ever had a customer that wanted to maintain 78°F in the winter and 72°F in the summer? They are not batty, they are using temperature to compensate for poor humidity control. However, overheating only increases static electricity, dry mouth, chapped lips, and other humidity related discomfort. So it fixes one problem, feeling cold, and creates a whole bunch of other problems. Adding a humidifier to their system will make them more comfortable by addressing the real problem, humidity. It also can save money because they can maintain a lower thermostat setting and still feel comfortable. 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 http://www.handsdownsoftware.com/Downloads.htm

Comfort Science

A few years ago someone came into my office asking for my help regarding installing an air conditioning system in his house. He was going to save money by doing it himself even though he had no training and had never run a piece of duct, much less installed a complete system. However, he was confident he could do the job after a five minute discussion with me to fill in any gaps in his information. “After all”, he said, “it’s not rocket science.” I must confess that after he told me more than once “it’s not rocket science,” I had no interest in even trying to explain to him the many pitfalls ahead. He had already determined that there was really nothing to know.

Air conditioning professionals can also be guilty of devaluing installation. Because installation involves more manual labor than service, it is easy to view installation as simply manual labor. After all "it's not rocket science." Nothing could be further from the truth.

I recently had an advisory committee meeting for my program. One contractor stressed that she really wanted people who would take installation seriously. She was especially emphatic that understanding airflow and airflow measurement was crucial. Another contractor mentioned that with the increasing complexity of today’s systems, including communicating controls and variable capacity systems, installing technicians really needed to understand how the systems operate. Yet another stressed that many customers will pay a premium price for a system that is energy efficient. However, if the system is not installed correctly they will be disappointed with the results. Another committee member mentioned that an Atlanta contractor had actually increased their sales by 27% this year. They are performing energy audits and system performance analysis and making selling customers solutions to improve system efficiency and overall comfort. Their technicians are closer to scientists than unskilled laborers.

Properly sizing and installing an HVAC/R system is “comfort science.” If you want the system to perform as advertized selection and design cannot be reduced to a square footage per ton factor and a six inch flex run for every room. After the system is chosen and the duct system is designed, it still must be installed correctly. A 20-SEER split system full of non-condensables will be lucky to operate at 13 SEER. A system with an ECM blower will use even more energy than a typical PSC blower if the duct is too restrictive. Setting up and checking out a communicating, variable speed zone system requires technicians who can read, understand, and interpret technical instructions. This is why I believe it is critical to teach the science behind what we are doing. As HVAC/R becomes increasingly technical, technicians who understand how and why machines work will become invaluable. Installing today’s increasingly technical HVAC/R systems requires technicians that are trained, understand how systems operate, can read technical literature, and can take detailed system performance measurements. In short – comfort scientists!

Fundamentals of HVAC/R has an entire section dedicated to the science of HVAC/R. These units discuss the science foundation of HVAC/R in a straight forward, approachable manner and give practical HVAC/R examples of its application. Units include:

• Unit 4 Properties of Matter
• Unit 5 Types of Energy and Their Properties
• Unit 6 Temperature Measurement and conversion
• Unit 7 Thermodynamics – The Study of Heat
• Unit 8 Pressure and Vacuum

Positively Thankful

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 affects your present and threatens 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.

Sometimes HVAC/R technicians have an opportunity to do more than make people comfortable, we can save lives. 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. Even people that should know better sometimes overlook the obvious. A friend of mine was conserving heat during a cold winter power outage by using his charcoal grill inside. His daughter became very ill and had to be rushed to the hospital where they correctly diagnosed her condition. This story ended well, she recovered and is doing well. Unfortunately there are many stories about CO that do not end well.

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/Aboutco.htm

http://www.clima-tex.com/consumer/carbonmonaction.html

http://annhyg.oxfordjournals.org/cgi/content/abstract/18/1/79

http://www.coheadquarters.com/colimits1.htm

http://www.coheadquarters.com/CarbonMonoxideHQ.com/index.html

Flue Season is Here!

No not the swine type, the furnace type! The weather is getting cold enough in many parts of the country that people are starting up their furnaces. Now is a good time to teach your students to check furnace flues during fall seasonal checks. The purpose of this article is not to discuss CO poisoning, but it deserves a mention since furnace flue problems can lead to carbon monoxide poisoning and CO poisoning shares many symptoms with influenza. One big difference is that influenza is normally accompanied by a fever and CO poisoning is not. For more information on CO poisoning check out the Carbon Monoxide Safety Organization web page.

A good place to start discussing furnace flues is to describe the four categories of vented appliances: Categories I, II, III, and IV. These categories are determined by the static pressure in the vent and the temperature of the vent gasses. For reasons of manufacturing and application limitations, Category II and III furnaces are rare. Most furnaces fall into either Category I or Category IV; 80% furnaces are category I while 90% furnaces are category IV. Category I furnaces are vented with type B gas vent. Category IV furnaces are usually vented using PVC. The combustion gas is cool enough to be safely vented through PVC and PVC is relatively easy to seal air tight.

In practical terms the vent gasses in a properly operating Category I furnace will not leak out small cracks because the vent gas pressure is less than the surrounding air. Vent gasses will generally not condense in a Category I flue because the temperature of the flue gas is considerably above dew point. Even though most 80% furnaces manufactured today have induced draft blowers, they still operate with a non-positive pressure vent because of the buoyancy of the hot combustion gas. However, the combustion gas coming from an 80% induced draft furnace is far more likely to condense in the flue than with older natural draft appliances. Oversized vents, single wall vents, masonry vents, or some combination of these can lead to condensation in the flue. Flue condensation can corrode metal vents and cause masonry vents to crack. Severe condensation can return water to the furnace and cause pre-mature heat exchanger failure. These situations most often occur when an older existing furnace is replaced with a newer, higher efficiency furnace. Even though the newer furnaces are designed for regular type B gas vent, they can not necessarily be connected to the old furnace flue. The extra heat in the combustion gas and the dilution air from the draft diverter of the older furnaces combined to make large single wall vent connectors and masonry vents work without condensation. The cooler combustion gas and lack of dilution air in the fan assisted furnaces makes their vent gas more susceptible to condensation. I have seen a single wall vent connector on an 80% induced draft furnace in a crawl space rust completely through and fall on the ground in a single year of operation. The furnace replaced a previous natural draft furnace that operated for many years without problems on the same type of vent. To prevent similar results when replacing an older furnace I recommend using only double wall vent and installing a metal flexible chimney liner when venting into a masonry chimney. An alternative to lining the masonry chimney is to vent horizontally using a power venter and not using the masonry chimney. More information on power venters is available from Field Controls

Another important step is to size the vent. The existing vent for the older natural draft furnace being replaced is often larger than is required for the 80% induced draft furnace. An oversized vent can also lead to condensation. You can download a pdf file on vent sizing from Hart & Cooley

Visual cues that furnace combustion or venting needs attention include: rust on metal vents, condensation weeping from vent joints, or carbon buildup anywhere in the vent system. Your students may run across non-condensing furnaces that were vented using a rigid plastic vent material called high temperature plastic vent, HTPV. This material has been recalled and should be replaced whenever it is found. HTPV recall If they see any of this material they should contact the furnace or vent material manufacturer or to find out what replacement vent material is recommended.

Fundamentals of HVAC/R can help your students prepare for flue season. Details on gas combustion can be found in Unit 37 Gas Fired Heating Systems. Furnace categories are discussed in Unit 38 Warm Air Furnaces. Vent sizing is discussed in Unit 40 Gas Furnace Installation, Startup, Checkout, and Operation. Gas combustion and venting problems are discussed in Unit 41 Troubleshooting Gas Furnaces.

The New 70

Many of the old timers I talk to who are still leery of R-410A want to know what the “new 70” is. They want a target number for the suction pressure of an R-410A air conditioning system. Many service technicians are in the habit of charging to a target number on the suction side. This is frequently 70 psig on R-22 systems. The saturation temperature of R-22 at 68.5 psig is 40°F and for many years the standard evaporator temperature at design conditions has been 40°F. But 70 is a nice round, easy to remember number and close enough for quickie rules of thumb. The problem is that systems seldom operate at design conditions. Another big problem is that conditions other than charge can cause low suction pressure. If a technician is only checking the suction pressure, they are not collecting enough information to recognize other system factors that can contribute to low suction pressure. A common error of inexperienced techs using the “70” method is overcharging systems that have low evaporator airflow. I have gone behind someone using the “70” method who had overcharged the system so severely the compressor stalled at startup and pegged my high side gauge past 500 psig. The customer was told that the compressor was bad. To be fair, most experienced technicians that use the “70” method understand how airflow and system operating conditions affect system pressures, they just don’t want to bother with manufacturer’s charts. They just modify the target up or down as they judge conditions affecting system pressures. These folks can usually get a system cooling; that is why they still have a job. However, the system will often not be performing optimally when they leave. Today’s customers are paying a premium for systems that are more efficient and have less environmental impact than older systems. Beginning January 2010, even the least expensive unit a customer can purchase will be non-ozone depleting and more efficient than the least expensive unit they could purchase just a few years ago. This means everybody is paying for efficiency and reduced environmental impact. However, if technicians don’t charge units properly, customers are not getting what they are paying for. Your students can be the vanguard of a new era that values professionalism. Make sure your students know how to handle new refrigerants like R-410A and know how to read and follow manufacturer’s charging charts. That will put them in a position of leadership early in their career.

Fundamentals of HVAC/R has a detailed discussion of system charging in Unit 27 Refrigerant System Evacuation and Charging. Variables affecting system pressures, common methods of determining the correct charge, and common methods of adding refrigerant are all covered. Charging is also discussed in other units including

• Unit 35 Residential Split system Air conditioning installations
• Unit 36 Troubleshooting Split System Air Conditioning
• Unit 52 Heat Pump Installation
• Unit 53 Troubleshooting Heat Pump Systems
• Unit 83 Troubleshooting Refrigeration Systems
• Unit 84 Installation Techniques
• Unit 85 Planned Maintenance
• Unit 86 Troubleshooting

What IS a Grain?

Learning all the different units of measurement HVAC/R technicians must deal with can be a daunting task for students. The inability to accurately describe what you need is a major barrier to performing your job. Understanding the different units of measurement used in the HVAC/R trade simply makes your job easier. However, all of us run into specifications or terms used in technical literature that we are not really familiar with. Knowing why we use certain units for particular measurements or knowing the historical background of the units helps me remember them. Ever wondered about the origin, definition, or use of an unusual unit of measurement? Maybe even one you use often but don’t really know much about? For me, the grain had been an enigma for years. Although I used it often when working with humidity and the psychrometric chart, it was always a bit of a mystery to me. The grain is a very small unit of weight: 7000 grains equals one pound. Grains are used to measure the weight of water in each pound of dry air when working with the psychrometric chart. Grains are a perfect unit of measure for that purpose, giving us reasonable whole numbers to work with when discussing very small quantities of weight. But why the name grain, and what measurement system did this odd 7000 quantity come from? I found the answers to those questions and more at a web site called How Many? A Dictionary of Units by Russ Rowlett of the University of North Carolina at Chapel Hill. It turns out that the grain was originally based on the weight of a grain of barleycorn in England, or a grain of wheat in France. The name is literal. Many of our common measurements are based on concepts and systems that go back hundreds of years. To introduce your students to the site, ask them to look on the site and find some air conditioning specific information, like the difference between American Wire Gauge and Metric Wire Gauge, or how the American Wire Gauge came up with the particular wire diameters it uses. Here is another challenge: how many of you know what the gauge of a shotgun is based on? To find out go to Mr. Rowlett’s site, How Many? A Dictionary of Units. However, I warn you that you can get lost for hours reading the intriguing background to common measurements.

The Formula To Success

A problem that many students have when beginning their study of air conditioning and refrigeration is that many of the most crucial concepts are traditionally presented primarily through math formulas. Even simple concepts become confusing when they are presented using traditional algebraic formulas that assign constants and variables for each measurement. For many students, algebraic explanations become barriers to learning. Presenting the foundation science conceptually and using analogies to common life experiences helps. If students understand the basic idea, learning the math that represents the idea is easier. That is why Fundamentals of HVAC/R presents science facts conceptually, not just as math formulas.

Take gas laws for example. Relate temperature to the average speed of the molecules: higher temperatures produce faster moving molecules; lower temperatures produce slower moving molecules. Next tell students to imagine gas pressure as the force of the gas molecules colliding with the sides of the container holding them. The more collisions produce higher gas pressure; fewer collisions produce lower gas pressure. Now tie the two concepts together: when a gas is heated the molecules move faster, increasing collisions with the sides of the container which increases the gas pressure. When a gas is cooled the molecules move slower, reducing collisions with the sides of the container which reduces the gas pressure. Discuss this point and ask questions to make sure they understand. After they have grasped the pressure temperature relationship you can introduce the related formula. Understanding the concept first makes the math a little easier to grasp because they have some context to hang it on. Remember it is more important for students to understand the pressure-temperature relationship than it is for them to calculate gas law formulas. Being able to work the gas law formula is not really the goal, understanding the temperature-pressure relationship is.

However, most standardized tests in this filed still rely heavily on manipulating traditional math formulas. So we also discuss common formulas that students are likely to see in HVAC/R literature and standardized tests, like the ICE or NATE. Throughout the book, whenever a formula is introduced, we give detailed examples showing step by step how the formula is used. To make the example formulas are easy to follow they are presented in the most straight forward, uncomplicated way possible. The text also uses practical examples showing the usefulness of the formulas that are introduced. Students are more willing to make an effort learning something that has a demonstrated application. Besides discussing formulas throughout the text whenever they are relevant, Fundamentals of HVAC/R lists many useful formulas in one place: Appendix B Commonly Used HVAC/R Formulas.

A good exercise in preparation for taking an industry standardized test is for the students to look through all the formulas listed in Appendix B and make certain they understand how to apply each formula. The unit in the text where the formula is discussed is listed beside each formula. This shows students where to look for a discussion and an example problem for any particular HVAC/R formula.

Teaching the Virtual Generation

Do you have students from the “virtual generation”? These are young people who are very bright, have great hand-eye coordination, but have never used a wrench because an increasing amount of their existence is online. They talk with their friends, do research, play games, and generally “live” online for a large part of their time. Studies have suggested that this actually improves their mental agility and problem solving skills, both valuable assets for service technicians. Unfortunately, their exposure and experience with real life tools and mechanics is limited to non-existent. HVAC/R mechanics rely on their tools for survival. It is not possible to install, service, or troubleshoot HVAC/R systems without tools. Having the correct tools for the job and knowing how to use them can be the difference between success and failure. That is why Fundamentals of HVAC/R devotes an entire section of the book to tools. The units in the Tools and Equipment section are:

Unit 9 Hand and Power Tools
Unit 10 Screws, Rivets, Staples, and Other Fasteners
Unit 11 Electrical Measuring and Testing Meters
Unit 12 Refrigerant System Servicing and Testing Equipment
Unit 13 Heating system Servicing and Testing Equipment
Unit 14 Calibration of Meters and Instruments

These units provide an overview of the tools used by technicians who perform HVAC/R work. The units are filled with high quality, full color photographs of the tools and equipment. These units not only show the tools, but also provide illustrations and descriptions showing how the tools are used. This is particularly important for more unusual tools. For example, the use of a duct stretcher is shown in Unit 9. Yes, there really is a tool called a duct stretcher!

One student confessed to me after he graduated that he had never held a wrench until he took my Air Conditioning class. What he didn’t know was that it was fairly obvious. The good news is that his innate intelligence and strong work ethic allowed him to overcome this and go on to be successful. We gave him lots of shop projects requiring tool use. We monitored, corrected, demonstrated, and advised as he progressed towards tool competence.

Before he graduated he took a job as a helper for one of the best refrigeration mechanics in town, who also happens to be a patient man. You see, the mechanic had cancer, and his ability to perform the physical part of the job was declining. The student became the hands and arms for a gifted mechanic. In the course of a summer became proficient at using tools. He has now been with that company for two years and loves his job and the people he works with. If you have bright eyed, eager students from the “virtual generation” show them how to hold a wrench, give them lots of shop work to practice their tool use, and be patient with them. They could end up working with the best mechanic in town.

It's Called a Compressor Because ..

How often have your students asked for study guides and hints before tests? Tell them that the hints are built into the terminology. In many cases, HVAC/R terms define themselves. The names for most components and processes are not randomly chosen, they are frequently drawn from general vocabulary to describe a component or process. For example, a compressor compresses gas. The word compress means to make smaller. When you squeeze something you make it smaller, or compress it. The compressor raises the pressure and temperature of the gas by squeezing it, making its volume smaller. If the students understand that compress means to squeeze, they should have no trouble remembering what the compressor does.

To truly understand HVAC/R terminology students should not simply memorize a list of attributes for the rather large number of HVAC/R terms, but should connect the function to the name. Making these connections also increases memory retention. The method that a compressor uses to accomplish its work is used to describe the types of compressors. Reciprocate means to go back and forth: a reciprocating compressor uses pistons that go back and forth in a cylinder. A scroll is spiral: scroll compressors use intermeshing spirals or scrolls to compress the gas. A screw compressor uses intermeshing auger shaped screws to compress the gas. Connecting the name to the function will help students get a mental picture of the device and increase both understanding and memory retention.

All the components of the refrigeration cycle have names that either describe their function or describe them physically. The key is for students to understand where the name comes from. If students understand that orifice is simply a three syllable word for hole, they should have not problem remembering what an orifice is. One of the reasons I believe in covering the science behind the refrigeration cycle before trying to discus the refrigeration cycle is so that these connections can be made. If the students already understand the processes of evaporation and condensation, they will have no trouble remembering what evaporators and condensers do. This same technique can be used for many aspects of HVAC/R. In electricity potential difference literally means the difference in electrical potential between two points. The refrigerant terms zeotropic and azeotropic can be better understood if you explain the vocabulary they are built on. For most of us, these words are presented simply as arcane terms for refrigerants that are mixtures of two or more refrigerants. The fact that they differ by a single letter makes remembering the difference between the two difficult. Most students complain that the two terms are “all Greek to me!” In fact they do come from Greek roots. “Zeo” is to boil, “trop” is to turn, so zeotropic refrigerants turn, or change as they boil. Placing the letter “a” in front means “not.” For example: amoral means without morals. Similarly, azeotropic refrigerants do NOT turn or change when they boil. Give a few vocabulary lessons and increase your student’s understanding and memory retention. For more HVAC/R vocabulary tips check out the glossary in Fundamentals of HVAC/R, the largest glossary in any major HVAC/R text.

Combustion Air

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 technicians view 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 also 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. In a room with inadequate combustion air, as the combustion process continues the pressure in the room becomes negative, reducing 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 the text Fundamentals of HVAC/R.

Comfortech 2009

I had the pleasure of attending the Comfortech Conference in Nashville, Tennessee this past week. A national convention like Comfortech provides the opportunity to meet and talk with industry leaders from all over the country. I set out to pick as many brains as possible. The people staffing the booths impressed me not only by their level of expertise and experience, but also with their generosity. I found that everyone was very willing to talk with me. When I introduced myself as an air conditioning instructor their faces seemed to visibly brighten. They wanted to talk about what they felt was important to teach. The people in our industry want to help us, because they recognize the importance of education to their own success.

Whenever I attend a national show I always look to pick up ideas for teaching. Many of these companies need to teach their potential customers in order to sell to them. In a trade show they do not have a captive audience, so they must get their point across quickly. I saw a demonstration by the National Comfort Institute on air filters that was compelling, simple, and quick. They had a blower set up with return and supply plenums, an external filter rack, and adjustable manual dampers on the end of both the return and supply plenums. They adjusted the dampers to achieve a total external static pressure across the blower of 0.5” water column, measured with a magnehelic. They measured the pressure drop across the standard 1” disposable filter as 0.05” water column. Then they replaced the filter with a 1” pleated filter and the pressure drop across the filter increased to 0.5” - as high as the entire system pressure drop before! Emerson was showing off their new communicating controls. They had a condensing unit board that handled all controls and power switching, including the compressor. No contactor! A little box about 1 inch square was switching the compressor! Rheem was using these boards in their newest units on display. I have to stop now because if I described all the cool stuff I saw my blog might be as big as my book. There were over 160 exhibitors, each with their own lessons. You can still see a list of the Comfortech exhibitors by going to the site where you can get links to many of the exhibitor’s sites.

I believe each of us should try to attend at least one national level convention a year. Most national conventions have a showcase event for vendors to display their latest and greatest. These are typically either inexpensive or free. There you can see the latest equipment, tools, and technology and ask questions face to face. If you missed Comfortech, don’t despair, there are several others coming up soon. RSES has its Annual National Conference coming up October 27-31. The grand-daddy of all HVAC/R conferences, the AHR Expo, will be in Orlando January 25-27 2010. The AHR Expo is a joint venture of ASHRAE and AHRI. There are two conferences aimed at HVAC/R instructors: HVAC Excellence National Educator's Conference March 14-16 2010 in Las Vegas and AHRI Instructor’s Workshop in March 24-26 in Landsdowne Maryland at the National Convention Center. Although each of these shows targets a slightly different audience, they are all very applicable to what we do. If you come to either of the instructor’s conferences you might see me. I will be there.

R22 Conversion

Most HVAC/R programs have a large number of R22 air conditioning systems in their shop. The ban on the use of R22 in new equipment begins January 1, 2010 – only a few months away. Although R22 will be available for servicing existing equipment, the amount of new R22 available is scheduled to be reduced by 75% in 2010. The EPA and many people in the industry believe that this will create a shortage of R22 in 2010. What this all means is that R22 will become more expensive and harder to get. I began exploring for an R22 replacement refrigerant to keep our shop equipment operating when R22 is either not available or not affordable. I would like to share a few things to consider when examining potential R22 replacement refrigerants.

Whenever possible check with the equipment manufacturer. Chances are they have some insight into what works, and more importantly, what does not work. Copeland has a six page service bulletin that discusses conversion from R22 to R422A and R422D in commercial refrigeration systems.

Copeland 422 Conversion

Tecumseh offers five service bulletins that discuss R22 refrigerant conversion. They are available at

Tecumseh Service Bulletins

There are a number of replacement refrigerants offered to replace R22 in existing systems. However, even if the system operates and cools, there are some potential negative outcomes that you should be aware of before proceeding.

Make sure that any refrigerant you propose to use has been approved for use by the EPA. You can check the SNAP list to see if the refrigerant is listed.

EPA SNAP List

There are many hydrocarbon based replacement refrigerants for sale on the internet which are NOT approved by the EPA for use in the US. Some are even manufactured in the US, but they may not be used in the US.

For the most part, most manufacturers do not endorse refrigerant conversions. Just because the EPA approves a particular refrigerant does not mean that the manufacturers must approve its use. Using a replacement refrigerant that is not approved by the manufacturer usually means any warranty is voided.

Systems may lose their UL approval since the UL testing was done with the original refrigerant. Many alternate refrigerants have been tested and classified by UL, but many have not. Consult UL or the refrigerant manufacturer to find out if the refrigerant is UL classified.

Zeotropic refrigerants (400 series blends) should never be used for flooded chillers. The refrigerant will separate in the evaporator. Since nearly all replacement refrigerants are 400 series blends there are very few acceptable non-ozone depleting replacement refrigerants for flooded chillers.

Finally, the refrigerant manufacturers will help. Even if you decide to proceed without the equipment manufacturer’s help you are not entirely on your own. The refrigerant manufacturer also bears responsibility for the application of their product. All refrigerant manufacturers offer application bulletins and guidelines for the use of their products. A few are:

Dupont

Forane

Honeywell

Smaller companies that primarily manufacture replacement refrigerants obviously have an incentive to help. ICOR has one of the most interesting support ideas – a toll free telephone number which you can call to talk to an experienced service technician.

ICOR Help

For more detailed information on refrigerants check out Unit 23 Refrigerants and Their Properties in Fundamentals of HVAC/R. For specific details on complying with EPA refrigerant regulations check out Unit 26 Refrigerant Management and the EPA in Fundamentals of HVAC/R.

Teaching Green Technology

I am sure by now everyone has heard about the green revolution. Chances are, you have been asked what you are doing to teach Green Technology? You might feel that you are not doing anything about teaching Green Technology, but I bet you are teaching Green Technology without realizing it. First, your students are already ahead because they are in school. They will be more likely to read and follow instructions than someone who is just “doing it the way we have been doing it for 20 years.” New installation and service techniques develop along with new equipment and technology. Installing a 20 SEER air conditioner incorrectly effectively erases its efficiency advantage. Therefore, the first and foremast Green Technology we should be teaching is correct system installation. Chances are the text you are already using discusses Green Technology. Fundamentals of HVAC/R includes 13 Units that include information relevant to Green Technology. Unit 54 Basic Building Construction , has a section on Green construction.The idea is the Green Technology is more than a separate device or product, but is a new way of thinking and doing things. These 13 Green Technology units are identified in the table of contents with a green asterisk after the unit title. If you are looking for a text that is specifically Green, take a look at Pearson’s Your Role in the Green Environment, or Green Building Fundamentals, or Sustainable Construction and Design. To read more about these texts visit pearsonhighered.com

http://www.pearsonhighered.com/educator/product/Your-Role-in-the-Green-Environment/9780136065968.page

http://www.pearsonhighered.com/educator/product/Green-Building-Fundamentals/9780135028391.page

http://www.pearsonhighered.com/educator/product/Sustainable-Construction-and-Design/9780135027288.page

I hear you saying “but they want me to buy a GREEN trainer!” No problem. I have two suggestions. One, get an ECM blower demo from thedealertoolbox.xom. It allows you to play with an ECM blower and measure the results. Not only will this help teach your students about Green Technology. it will help teach them about airflow. You can read more about it at http://secure.thedealertoolbox.com/p-20-ecm-blower-demo.aspx

Another obviously Green HVAC/R product is the new Lennox Solar Assisted Heat Pump. They are selling a heat pump with a solar panel that produces part of the electricity the heat pump uses. You can see more about it at http://www.lennox.com/pdfs/brochures/Lennox%20XPG20%20Heat%20Pump.pdf

If you are exploring Green Educational programs there are several alternatives ranging from a simple Green Awareness program to offering instruction in fields like Testing and Balancing or building Commissioning. If you would like to offer a Green Awareness program and certification you might check out ESCO’s Green Awareness program http://escoinst.com/GreenawerenessCertification.htm

Testing and Balancing and Building Commissioning are professional fields requiring specific training and credentialing, but if your school is serious about being Green, they are areas to look into. Without testing and balancing and commissioning, you really don’t know if the building and systems are performing as designed. You can get more information on Testing and Balancing at http://www.nebb.org or http://www.tabbcertified.org/ For building commissioning check out the Building Commissioning Association http://www.bcxa.org/ or the “Whole Building Design Guide” by the National Institute of Building Sciences http://www.wbdg.org/project/buildingcomm.php

The big mac daddy of Green right now would have to be the LEED program designed by the US Green Building Council. Buildings are certified as meeting the LEED standards by earning points in a variety of areas from energy efficiency, materials used, recycled content, and waste disposal to name a few. LEED buildings must be inspected by a LEED certified inspector. This offers another training opportunity. To read more about USGBC and LEED go to http://www.usgbc.org/

Again, I firmly believe that the HVAC/R field can be considered a Green Field when done correctly. After all, the Greenest design on paper turns brown if it is not properly installed.

Teaching Ohm's Law for Parallel Circuits

Many students have a hard time understanding why the total resistance of a parallel circuit decreases as loads are added in parallel. Comparing lanes on a highway to loads in a parallel circuit is an analogy that works for many people. Adding another load in a parallel circuit is like adding another lane on a highway. The more lanes you have, the more traffic you can move. So as lanes are added, the resistance to traffic flow decreases. In parallel circuits, the more loads you have in parallel, the more current you can move. So adding loads in parallel decreases resistance to current flow. 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.If you want to have some fun, take a parallel circuit calculation and use a number other than one, say 5. Divide each resistance into 5 to get the current for each load at 5 volts. Add all the individual currents up. Finally divide this total current into 5 to get the total resistance. You get the same answer as when you use 1! To prove it to yourself, do the same set of resistances with several voltages. If you don’t stumble on the math, the answer is always the same regardless of the number you start with.

Understanding Centrifugal Fan Motor Performance

Since air is what we work with it makes sense to insure that our students understand airflow and fan performance. Fan motor performance is one of the most often misunderstood aspects air conditioning systems. The amp draw on a centrifugal fan goes down as resistance to airflow is increased. For most people this seems counterintuitive. It is easy to picture the fan motor pushing harder to overcome the resistance and increasing in amp draw. However, this is exactly backwards. Centrifugal fans move air by throwing the air outwards through centrifugal force. The amount of air the fan is moving decreases as the resistance to airflow increases. If the fan blades are moving less air, they can actually spin easier because there is less air to sling. This causes the motor RPM to increase and the motor amp draw to decrease.

The most convincing way to teach this concept is to have students figure it out for themselves using a centrifugal blower. Have them operate a centrifugal blower in free air with no restriction and measure both the amp draw and the fan RPM. Note that most centrifugal blowers cannot operate in free air for an extended time without overheating, so try and keep the free air operating time to a minimum. Next have them block one side of the air intake with a piece of cardboard and recheck the amp draw and RPM. Typically the increase in RPM is immediately obvious, but measurements prove the point. Have them slide the cardboard to block the intake only half way while watching the amp draw. A few minutes of experimentation will convince the students that blocking the intake actually causes an increase in RPM and a decrease in the motor amp draw. Next have them partially block the fan outlet while checking the amp draw. Once again, the amp draw will decrease. Allow them a few minutes of play time to convince themselves. This experiment does more to explain centrifugal blower motor performance than a week’s worth of lectures.

Now that you have them hooked, refer them to Unit 56 Fans and Airflow inFundamentals of HVAC/R where they can read about the characteristics of different type of fans used in the industry and the basic principles of airflow. There the students can see examples of the different types of fans and read about their performance characteristics. Unit 56 Fans and Airflow wraps up with a discussion of the fan laws and using fan perfromance tables and curves. As always, examples show in detail how to apply each of these concepts.

Note that what I have been discussing assumes a "regular" PSC blower motor. ECM blower motors behave differently because they are programmed to adjust their output according to the resistance they are working against, but that is an entirely new discussion which I will save for another article.

Safety note: If you are not sure all of your students understand that it will hurt to put their hands into a moving fan blade, you should put a wire gaurd over the intake and exhaust to keep hands and fingers out. For a more polished trainer build sliding sheet metal baffles for both the intake and exhaust and mount the blower to a stand.

To see all my posts be sure to vist hvacrfundamentals.blogspot.com

Teaching Residential Design

One of the challenges that all HVAC/R educators face is convincing future contractors to ignore all the quick and easy rules of thumb for system sizing and duct layout and use design methods based on research. The problem with the ACCA standard design methods for sizing equipment and designing systems is that a considerable amount of time must be invested to understand how to use them. The first few systems someone does with Manual J and Manual D seem to take forever. Even using a computer design program requires the user to learn how to use the program. These methods appear overly difficult when compared to simple square feet per ton rules, or air changes rules. Still, the question really comes down to “do you just want an easy answer, or do you want a correct answer?” If you think from the customer’s perspective, they really want and need a correct answer. I believe that it is also in the contractor’s long term best interest to get correct answers as well. Avoiding a gaggle of unhappy customers that got the quick, easy, and wrong answer can be more time consuming than taking the time to get it right the first time.

I don’t think every Air Conditioning Technician needs to be able to whip out a Manual J load study, but I do think all technicians should be familiar with the overall concepts and general procedures used. Sometimes, the first step to learning is understanding how much you don’t know. Introducing technicians to the proper way to do a load study can be the light in the darkness that illuminates the path to greater understanding.

The truth is that the procedures are really not that difficult once you understand them. They will still take more time then dividing the square footage by a magic number, but an accurate load study on a typical residential home generally takes less than 30 minutes for someone who understands the process. It is true that you will have to invest hours of your time to get to that point, but that is really no different than any other skill that is required to perform HVAC/R work. The fact that time and effort are required to develop the skills and knowledge required to perform the job is part of what makes HVAR/R jobs valuable. The job is not as simple as memorizing a handful of rules of thumb.

Section 7 in Fundamentals of HVAC/R gives students the information they need to understand residential air conditioning application and system design with several unique features not found in other major air conditioning texts. The System Design, Sizing, and Layout section begins with Unit 54 which describes how buildings are constructed. It is important for students to understand how the air conditioning system fits into the building. Decisions about unit location, duct location, general duct design, and register placement are all very much affected by the building construction. Unit 55 shows students how to read and interpret drawings. Often, the first “look” an air conditioning technician has at a building will be in the form of a drawing. Teaching students how to interpret blueprints allows them to understand the building construction, even before the building is built. Unit 64 takes the students step by step through a manual J8 load calculation. Fundamentals of HVAC/R is the only major text to discuss the use of Manual J8, the latest version of ACCA Manual J, the ANSI standard for residential load studies. Unit 57 shows students the types the different types of duct systems available and how they fit different types of building construction. Unit 58 shows how to install duct systems and how to use friction charts and the ACCA Duct Calculator to design duct systems.