air filter dirty detailUnderstanding how indoor air quality affects the HVAC system is something every homeowner should understand. It may seem like two separate issues, but the truth is that unhealthy air quality can reduce HVAC system efficiency in a big way. Anything from visible dust to tiny, nearly invisible particles can cause premature system failure.


Common household dust typically contains lint from fabrics, dead skin cells, pollen and animal dander. All forced-air HVAC systems use air filters to trap these particles, but their ability to do so depends on their density and cleanliness.

Besides covering the blower’s motor and all the electrical components in the air handler, these particles can also cover the evaporator coil for the air conditioner or heat pump. When any of these components gets dusty, performance is impaired.

Particulates can even cause serious problems with the compressor, the system’s most expensive part. Dust insulates the coil and slows the heat exchange process, causing the coil to freeze, which harms the compressor.  If you use a heat pump for heating in the winter, you’ll also lose heating efficiency.


Mold spores, bacteria and viruses are not only bad for your health, but they’re also not good for your home. They exemplify how indoor air quality affects the HVAC system. These minute particles can be pulled through the system, landing on the evaporator coil where mold spores can grow and biofilms develop, reducing the efficiency of the coil just as dust does. Mold can thrive in ductwork and the spores can land anywhere. If there’s enough moisture in the air, it can cover many surfaces in your home.


Using the highest efficiency air filter you can and changing it monthly helps reduce problems associated with poor indoor air quality. Ultraviolet (UV) lights placed inside the ducts or inside the air handler help stop the growth of bioaerosols indoors, potentially improving personal health and eliminating some HVAC system problems.

To learn more about how indoor air quality affects the HVAC system, contact Gentry Heating, Inc. We’ve provided trusted HVAC services for Asheville area homeowners since 1963.

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