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There are many types of filter and variables.  But here is the basic rule to start with.


  1. Flat panel 1″ thick.   Change every 30 days. So 12 times a year.
  2. Pleated 1″ thick.  Change every 90 days. So 4 times a year.
  3. Specialty air filters such as SpaceGard, AprilAire, Air Bear or Cub, Honeywell, General.  These filters are 3″ to 5″ thick and should be changed once a year.
Variables that shorten a filters life
  1. Pets
  2. Smokers
  3. Above normal household traffic
  • If you have 1 of these variables check you filter at 1/2 it normal life and see how it looks.  If you see build up and or darkened media, replace it.  If not not check it again at 2/3 life.
  • If you have 2 of these change it at half its normal life.
  • If you have 3 of these, check it after 1/3 its life.  If you see build up and or darkened media, replace it.
  • Make notes (and leave them with your furnace papers) on filter conditions and filter change frequencies to help you next time.
Reasons to stay on top of this
  • Dirty filters waste energy heating or cooling you home
  • Dirty filters put a strain on your furnace or air conditioner, increasing furnace repair bills
  • Dirty filters shorten the life of your furnace or air conditioner
Free Advice
  • Always use a good filter
  • Always remember to change your filter
  • Remember changing a filter is a lot cheaper than not changing a filter, think furnace repair bills



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