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Why does your HVAC filter get dirty so quickly?

Responsible homeowners know to replace their heating/air conditioning air filters on schedule. But sometimes, “on schedule” isn’t often enough.

Here are some common reasons why a filter will clog faster than average:

  • Pet hair. If you have one or more shedding pets, this contributes to extra dust and hair clogging the filter.
  • Your fan is set to “on”.There should be two fan settings on your thermostat — “on” and “auto”. When the fan is set to “auto”, it only blows during heating or cooling. But when it’s set to “on”, it runs continuously, which means air is passing through that filter 24/7, collecting dust.
  • Your filter has a high MERV rating. The higher this rating is, the smaller the particles the filter traps. An inexpensive fiberglass filter lets smaller particles pass, a thicker, pleated filter will catch those particles. Capturing more particles makes your air cleaner, but it accelerates the wear on your HVAC fan, and you may have to replace them more often. Your HVAC technician can help you choose the best filter for your situation.
  • Dusty home. Whether it’s from a recent home construction project or just accumulated dust in seldom-used rooms, the dust has a chance of ending up in the filter.