Mike Murphy

Ventilation. Ventilation. Ventilation. The three most important words in the HVAC business. OK, maybe the three words should really be airflow, airflow, airflow.

But, no matter how you slice it, the air has got to go in, the air has got to go out, and the air has got to move around. Just for fun, let’s say that the V in HVAC represents all the air, no matter which direction it is going.

Having met a number of heating contractors, cooling contractors, heating and cooling contractors, and some heating and a/c contractors, I have come to a conclusion - I’ve never met many ventilation contractors. Though most do have HVAC brightly emblazoned on their trucks and vans, the ventilation aspect of this business does seem to get short-changed.

Sometimes, the V gets almost entirely left out of the equation. Think about it. How many times have you walked into a building to repair a system and only looked for the obvious answer to the often-asked obvious question: “What seems to be the problem?”

The answer is usually something like: “It’s not working,” “It makes a loud noise,” “It’s too hot,” “It’s too cold,” or “I don’t know, that’s why I called you.”

Once you have made the system work again, or taken away the loud noise, or made it cooler or warmer - what next? The what next might just be the reason why the customer really called you in the first place. Once the apparent problem has been solved, it may be time to determine the origin or root cause.

After all, if the root cause isn’t treated, the problem might come back. It would be similar to treating a symptom, such as a fever, with an aspirin. The fever may go away for a few hours, but it will come back if the patient is suffering from malaria.

If ventilation has not been a regular part of your HVAC vocabulary for a while, perhaps now is a good time to get back in the routine.


According to recent research, HVAC systems account for about 40 percent of all energy consumed in commercial buildings, and “As much as half of the energy used in your home goes to heating and cooling,” according to www.energystar.gov. The Energy Star™ site goes on to say, “In fact, improper installation can reduce system efficiency by up to 30 percent,” and “sealing and insulating ducts can improve the efficiency of your heating and cooling system by as much as 20 percent - and sometimes much more.”

Commercial building owners and homeowners are fairly well tuned in to cost-saving measures, especially during this rough patch in the economy. But, how many of them understand the problems that can be brought on by improper airflow? Here is where the people who put the V in HVAC can step forward. Energy Star estimates that as many as 70 percent of all systems are not operating at their peak because of improper airflow. That means a poor installation is at fault.

Some might think of a poor installation as one that is improperly matched between the outdoor and indoor units, or one that has an improper refrigerant charge. All true; but what about the ductwork system that is not properly taped or sealed with a mastic product, or one that is improperly designed to begin with?

Both ailments likely occur much more often than anyone would like to admit. Duct leakage is a known thief of comfort and energy efficiency. Can a 16 SEER a/c unit deliver 100 percent of its efficiency if 20 percent of the air is whistling through unsealed crevices, the equivalent of a gaping hole the size of a basketball? Now, that is what I would call March Madness.


If ventilation really is the most important component of a properly installed system, then why isn’t more attention paid to it? In fact, many contractors do expend a lot of effort to ensure proper duct design, installation, and performance. It just makes sense. If the air can’t get to where it was intended to go, all the expert craftsmanship and top-notch equipment in the world won’t make much of a difference.

So where does a company find training to help learn the airflow basics if they don’t already know them? Here are a few ideas: www.acca.org, www.mcaa.org, www.smacna.org, www.msca.org, www.hvacreducation.net, www.nationalcomfortinstitute.com, or just bounce around the pages at the Learning Center at our own www.achrnews.com. There are plenty of resources available.

It might be a good idea to beef up on your V fairly soon. California began inspecting duct systems for new installations about two years ago through its Title 24 program.

Murphy’s Law:An HVAC axiom: As California goes, so goes the nation.

Publication date:03/16/2009