Derek ColeGM, Simmons One Hour Heating & Air · AI HVAC Answers

My Air Filter is Always Clean

9 Jul 2016 · 1 min

Watch on YouTube

1:12

In this YouTube segment, HVAC specialist Derek Cole explains why an air filter may remain visibly clean, which is a warning sign rather than a positive condition. He outlines three primary reasons: (1) the installed filter media is so low‑quality or thin that it fails to capture particles; (2) the return airflow is bypassing the filter entirely, often due to a faulty return design; and (3) the ductwork or return is so leaky that unconditioned, dirty attic or under‑house air is recirculating back to the unit without passing through the filter. Cole stresses that dirt accumulation is a leading cause of HVAC breakdowns, and that a clean‑looking filter often indicates that the system is not filtering air as intended, which can lead to overheating, reduced efficiency, and premature component failure.

Chapters

Filter never gets dirty. That is not good. One, could be the filter you're putting in is so, so terrible, it's so bad, it's so thin that it's catching nothing as it comes through, right? So it's staying clean that way. Or it's just bypassing the return altogether and not going to the filter. So it's not— it doesn't need to get the return because the house or the duct is so leaky that it's coming back to the unit through that method and not through the filter, which is what it's designed to do. The reason you want it going through the filter is because you want that cool conditioned clean air coming back to the unit, not the dirty hot under the house in the attic air coming back to the system. Makes sense? So one of the big problems is dirt. So dirt is the cause of most breakdowns. And the reason being is because that filter at the point where it's supposed to filter that air before it gets into the unit it. It's not doing that. It's not getting to the filter. It's not coming through the filter. Or if it is coming through the filter, the filter is not stopping it from getting through, and that is also a problem.