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.