Comfort to the Maxx

January 07, 2010
January/February 2010
A version of this article appears in the January/February 2010 issue of Home Energy Magazine.
Click here to read more articles about HVAC

In the September/October issue of Home Energy, which includes the Home Performance Contractor’s Business Development Guide, David Butler makes an important point about home performance contracting (p. 6):

“The home performance industry is largely unprepared to provide HVAC guidance. This is incredibly ironic, considering that HVAC is by far the largest energy user in the home.” Having gone through home performance training, I find this rings true. A few years ago, when I started doing home energy audits, it became painfully obvious, very quickly, that the training I received had taught me very little about HVAC systems. I was able to advise clients about dangerous conditions, as per the Building Performance Institute’s combustion testing standards. To resolve comfort issues, I would suggest duct sealing and possibly equipment replacement. To address energy efficiency, I would recommend high-efficiency equipment. After offering that sage advice, I would point the client to a few local HVAC contractors with good reputations, washing my hands of the whole situation. It never felt quite right, but in hindsight, it’s downright embarrassing.

Some HVAC contractors are getting home performance training and putting it to good use. Likewise, a few home performance contractors are trying to learn as much as possible about HVAC equipment, but it’s not easy. If we really want to build energy-efficient homes, and retrofit existing homes so that they are as efficient as possible, we need to address this issue much more broadly. The question is, How can a home performance professional get a high-quality, real-world HVAC education?

You could become familiar with all the ACCA manuals, and learn how to calculate building loads, select properly sized equipment, and design proper duct systems with the help of any one of a number of software applications. That’s one approach, although I know quite a few HVAC and home performance professionals who say that blindly following the ACCA guidelines usually results in oversized systems. You could also take as many classes as possible offered by your local utility company. Here in California, Pacific Gas and Electric has free classes almost all year, many of them devoted to HVAC issues.

The National Comfort Institute (NCI) takes a different approach, one that it calls Performance-Based Contracting. Over the past several years, it has collected diagnostic information about tens of thousands of HVAC systems. Using this information, it focuses on identifying and correcting installation and performance problems. Forget textbook solutions—the folks at NCI like to use real-world data. Its expertise is offered in two classroom-based training courses: Carbon Monoxide and Combustion Analysis Training, and Air Balancing and HVAC System Diagnostics. I recently finished both courses. The first class was in Sacramento, the second in Pasadena.

Be Afraid, Be Very Afraid

Jim Davis—a self-described Bad Boy of Combustion, teaches the Carbon Monoxide and Combustion Analysis class. (If he had a theme song, it would be either “He’s a Rebel” or “I Fought the Law.”) He’s been doing combustion analysis and CO testing for more than 30 years.

The class is divided into three sections, taught over three days. The first section focuses on the hazards of CO, the state of the CO-testing industry, and some basic diagnostics. It’s very scary. Jim could write a book about his experiences, the deadly things he’s seen, and what he thinks about various professions that are involved with CO. Let me summarize this last point, just to give you a flavor for his style. He contends that your local gas company probably doesn’t know how to diagnose and fix CO problems; your local fire department doesn’t know how to identify CO-specific hazards or how to minimize any hazard that it manages to identify; doctors don’t know how to properly treat victims of CO poisoning; and code officials don’t have any idea what they’re doing when it comes to CO or combustion standards.

The second and third days cover combustion appliance testing, with an emphasis on water heaters and furnaces; a final certification test; and, if you’re lucky, some hands-on time testing real equipment.

Over the years, Jim has developed very detailed, very specific protocols for testing almost every type of combustion appliance. He’s developed these protocols based on field experience, not building codes or engineering standards. The tests, which include CO, flue draft, flue temperature, and oxygen tests, typically take just a few minutes, but they diagnose a wide range of problems. Jim’s protocols also help identify possible repairs or adjustments, some of which can readily be done by someone with modest HVAC experience and a steady pair of hands. All this is possible with minimal equipment. Accompanying each protocol is a detailed worksheet that you can take into the field to record numbers and do some diagnostics.

This course contains a wealth of information that will probably adjust the way you think about CO and combustion diagnostics. I know it rotated my brain about 145º. You can sign up for any one of the three days. The full three-day course, which I recommend, currently costs $785, including certification, for non-NCI members.

A Balancing Act

The following week I took the Air Balancing and HVAC System Diagnostics course, taught by Rob Falke, NCI president. NCI's Air Balancing and System Diagnostics courseLike Davis, Falke has years of field experience. The focus of this two-day course is testing and diagnosing HVAC performance problems. (There is a third day devoted to light commercial testing.) According to NCI’s materials, which were developed based on testing thousands of HVAC installations, typical system performance averages about 57% of equipment rated capacity. That means that 40¢ of every $1 you pay for heating or cooling is wasted. The purpose of this course is to recapture as much of that 40¢ as possible.

The first day, using just a manometer and a thermometer/ hygrometer, you learn how to calculate static pressure, system component pressure drops, fan air flow, delivered BTU, and overall system efficiency, using protocols called HeatMaxx and CoolMaxx. The second day focuses on calculating proper air flow to each room, using a flow hood to measure the actual air flow, and determining ways to improve overall system performance. This process is called ComfortMaxx. In this course, as in the CO course, NCI provides specific, detailed forms and protocols for recording field data and doing the analysis.

Probably the trickiest of the calculations is determining proper system air flow. To really nail that number, you need the manufacturer’s equipment specifications. Unfortunately, they’re sometimes difficult or impossible to find. Based on its experience, NCI has developed generic specifications for different types of equipment that it claims are within 3% on average of real performance for various configurations. NCI has also developed general rules of thumb for calculating room heating and cooling loads quickly and easily in the field without having to resort to a full Manual J calculation.

Like the CO course, Air Balancing and HVAC System Diagnostics is a good course with a wealth of information. I’ve been exposed to much of the information and concepts through both my home performance training and my local utility training. This two-day course, which costs $590 for non-NCI members, kind of pulled it all together for me.

Performance-Based Training Years of experience and field data have gone into the development of NCI’s training materials. The real question is, Are these courses an effective way for non-HVAC professionals, such as home performance contractors, to improve and expand their HVAC knowledge to a level that can benefit clients? The answer is yes and no.

First of all, these courses are designed for people with a fairly strong HVAC background. Most of my former classmates are in the HVAC industry in some capacity. The CO course had two people out of seven with home performance training; the HVAC course had three California-style HERS raters out of about 15 people, one with some decent HVAC background. You really need some HVAC experience before taking these courses, just so you understand the terminology and concepts that most of the students take for granted.

Second, these courses are not a substitute for hands-on field training. In the CO course, we did visit a real home and ran some diagnostics on the water heater and the furnace. (Envision five combustion analyzers simultaneously stuck into one side of the draft hood of a water heater, with three sets of hands holding them; or eight people stuffed into an attic crawlspace huddled around a fired furnace.) As part of the final exam, we also did quick individual testing on a really old furnace. Unfortunately, there was no hands-on time in the two-day HVAC course. The closest we got to a flow hood was to look at two of them sitting on the floor in the front of the classroom. It seems the basic NCI philosophy is to provide you with tools and information, and then it’s up to you to go out there and start testing. That’s easy for people in the HVAC industry—not as easy if you do primarily home performance work.

Like most good courses, both of these courses had topnotch instructors. The printed materials and the notes you take can’t possibly substitute for the stories and insider details that a good, experienced instructor brings to the classroom. This makes both courses excellent candidates for video presentations. The downside to all the extra informal content is that the official material is never completely covered because the instructor runs out of time. That was true in both classes. We ended up rushing on the last day, skipping whatever material the instructor decided was optional, particularly in the HVAC course. I could use more teaching and less story telling.

At the end of each course, you get a certification. Based on my experience, it should be called a certificate of completion, instead of a certification, which implies a measure of expertise. First, the final exams are lightweight. You’re spoon-fed the answers throughout the classroom time, and the passing grade is 70%. I’m pretty sure that most people passed just fine without a lot of head scratching or angst. Second, it’s kind of ironic that although NCI bases its material on extensive field experience, it downplays hands-on time in its course work I came out of both courses feeling like I’d just been exposed to a lot of new information, but that I didn’t have a solid grasp of that information.

NCI is as much a marketing organization as a technical training company. The HVAC class is designed to teach HVAC professionals how to evaluate systems so that they can sell new equipment or a duct renovation to a homeowner. The end game is not the diagnosis as taught in the class; it’s the follow-up sale. Fortunately, it just so happens that the diagnosis is also useful in its own right. In addition, the company offers memberships in various support groups, advanced classes, extended memberships, a CD-ROM with company-customizable forms, discounted tool prices, and much more. It does provide free tech support for 30 days for the HVAC class, and Jim Davis claims that you can call him any time, day or night (except for a few hours on his anniversary and his wife’s birthday). In addition, in each class you get a CD-ROM containing the basic NCI protocols and forms.

I’m not sure it’s possible to get this kind of information anywhere else. The fact that NCI hosts each of these courses once a week, almost every week, certainly suggests that there are lots of professionals looking for more. In my search for a solid HVAC education, the NCI courses certainly added to my knowledge, but they didn’t really answer the question, How can a home performance professional get a high-quality, real-world HVAC education? Unless the answer is simply practice, practice, practice.


If you want a quick summary of diagnostic procedures for evaluating the efficiency of an HVAC system, you might want to pick up a copy of Al D’Ambola’s Air Diagnostic/Troubleshooting: Pocket Guide for Residential Duct Systems. This 3-1/4 inch x 6-1/4 inch spiral-bound booklet, printed on heavy card stock for repeated field abuse, clearly outlines the procedures required to do much of the analysis taught in the first day of NCI’s HVAC diagnostics course. At a cost of $19.95—about $2 per page—it’s a bit expensive, but it’s useful. Note: It won’t teach you the procedures, or help you to understand what you’re doing; it will just help you to remember the steps when you’re standing in front of a piece of equipment.

Steve Mann is a HERS rater, Green Point rater, LEED AP, Certified Energy Analyst, serial remodeler, and long-time software engineer.

>> For more information:
Steve Mann can be reached by e-mail at D’Ambola, Al. Air Diagnostic/ Troubleshooting: Pocket Guide for Residential Duct Systems. Avon Lake, Ohio: D’Ambola Associates. To order a copy, visit
To learn more about NCI, visit

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