Arkansas HVACR NewsMagazine September 2018

S tate, National, Chapter News Education News

Return leaks —the house goes positive and that is not a positive. With return leaks, air from non- conditioned space is drawn into the return and less air is returned from the conditioned space. When the house is positive, you don’t have to worry about air being sucked down ventilating piping but the air that the coil sees is no longer the set temperature of the house but is actually greater in the summer and colder in the winter. That decreases efficiency, efficacy, and comfort while increasing run time and the utility bill. As you can see duct leakage is a major problem to the homeowner. The difficult task for the HVAC installer is that he can’t see the air leaking. Unlike the plumber who can easily identify a water leak, the HVAC installer assumes everything is OK because the leaking air is invisible to the eye. However, it is visible to the instrumentation of a duct blaster. Testing duct systems with a duct blaster is as much for the HVAC contractor as for the consumer. Our industry wants to do a good job and deliver full value for the price paid. Duct testing assures the contractor that his was a job done well. That gives peace of mind and a great story to tell the next prospect. It is good for everyone. One last note, you do not have to purchase your own equipment and test your own ductwork. You can hire a third party.

What is the value for all this duct testing?

Well, as far back as 1991, a study found that duct leakage in Arkansas, Florida, and the Pacific Northwest was increasing heating and cooling energy consumption by 25% to 40%. That is huge for a consumer— Arkansas consumers. Duct leakage also creates positive and negative pressure in a home. For example. Ducts do not leak --the house is at stasis. That is, the air that was returned was supplied to the conditioned space and the cycle repeats itself. Air infiltration and ventilation changes house air with the non-conditioned space but the HVAC unit does not aggravate or accentuate the process. Supply leaks —the house goes negative. Why, because part of the air that went through the return was thrown away to the non-conditioned space. Since more air was removed than supplied, the house goes negative and “sucks” air from whatever source is the least restrictive. That may be combustion ventilation vents; i.e., gas water heater or gas heater in the conditioned space, fireplace, bathroom or kitchen ventilation, and from all the cracks and crevices that are in most homes. Natural ventilation is increased / exacerbated by whatever degree the supply ducts leak.