How Often Should I Be Changing My Air Filters?

This seems to be the magic question.  We are asked this all the time.  The simple answer is, “as often as they get dirty.”  Seems simple enough, right?  Let me explain.  Every home or business is different.  Each one has different occupants and is used differently.  One home may have a family of four with a dog and a cat while another may have single occupant.  As you can imagine, the one with a family of four with pets should be changing their filters more often.  Why?  More people means more dust and pollutants and pets can multiply this several time over.  

There are a couple of myths out there that should be put to bed before we continue.  It has been said that household dust is comprise of mostly dead human skin cells that have been shed from our bodies.  Although these skin cells are indeed in the dust in our homes, the claims that eighty plus percent are these cells is just not true.  Dust contains many elements such as dust mites, animal dander, insect waste and good old fashion dirt.

All this being said, you should check your air filter at least once a month to see how dirty it is getting. Below you can see a clean filter next to a filter that is past the point of being changed.

Most of the time it is pretty obvious that an air filters is in need of replacing but here are some signs to look for that can tell you it’s time to change it:

  • If your air filter is damp or wet
  • If the filter has been pulled into the unit by the air flow
  • If you hold it up to a light and little or no light is visible through the air filter
  • If the amount of air coming out of your registers and grilles has gone down significantly
  • If there is a build up of dust on your registers or grilles (air has started to bypass the filter)

Our best advice is to check it once a month when you pay your power bill seeing how your air filter has a direct impact on the performance of your heating and cooling system.  If it’s dirty go ahead and change it.  If not, check again in a week or two.  Once you do this, you’ll get a feel for how often the air filters in your own home should be changed.