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Blower Door Testing For Residential HVAC Systems

From what I can gather, it seems as though many residential HVACR service technicians and service companies are of the opinion that there’s not a lot of opportunity when it comes to offering blower door testing to customers. I disagree.

The number of homeowners who are interested in having their HVAC system and their home evaluated to make sure they’re not wasting energy (money) is growing steadily, and technicians who understand the fundamentals of testing a building envelope for tightness can explain the benefits of blower door testing to their customers while they are there either on a service call to solve a problem, or if they are there for a regularly scheduled preventive maintenance check.

I’m not saying that a technician will be able to sell….there I go, I said the four-letter word, but it’s a reality that shouldn’t be looked upon as a negative….a building evaluation on every service call. After all, in some cases, the customer can barely afford the service call, labor and parts cost of, say, replacing a failed condenser fan motor. But, in some cases, the customer has the resources, and they are willing to entertain the idea of a blower door test if they understand the benefits of it.

They key to this is to first educate the technician on the fundamentals of the procedure, and the second step is to put together a simplified information sheet that explains the process of blower door testing to the customer. In the simplified graphic below in Figure One, the concept of a building envelope is illustrated.


Figure One
Figure One

 With this simple illustration, a technician can show and explain to a customer that cracks and problems regarding their building envelope can allow unwanted air into the conditioned space from either the outside or through unheated areas adjacent to the conditioned space. In our illustration here, the bold line shows the building envelope and its possible exposure to both outside air directly, or through the unheated attic space.

This just makes simple sense to me. If the outdoor ambient temperature is somewhere in the 90s and the humidity level is 70 or 80 percent, having even a small percentage of that outdoor air being drawn into the building in an uncontrolled manner through cracks and past whatever insulation, tar paper, etc… that are elements of the building’s construction materials, will have a negative effect on both the performance of the system from an unnecessary heat load perspective as well as the indoor air quality in the conditioned space.

And, another element of that simplified information sheet can show what blower door test equipment looks like. (See Figure Two below.

Figure Two
Figure Two

As this illustration (equipment manufactured by Retrotec) shows, the technician can explain to the customer that the testing process involves positioning a blower assembly in a doorway, then using an electronic device that is capable of accomplishing very precise measurements in order to evaluate the tightness of the building envelope and identify potential problems that need to be solved in order to make sure that the HVAC system is operating as efficiently as possible.

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