Heating, Air Conditioning, Fridge, HVAC/Filtrete Filter for AC Return


Hi J,

My ranch home has a 2 ton Rheem unit in the attic with a 20x20 inch return for a 1350 square foot six room home. The system was installed in 2003. The brick home has R11 in the walls and 8 inches of blown loose insulation in the attic.

I have been using the fiberglass easy to see through filters since buying the home in 2005 as did the previous owner.  Due to my dust and pollen allergies, I was considering using the 3M Filtrete air filters which removes 92 percent of the dust from the air. These filters filter material are folded and remind me of an accordion because of the folds!

The Filtrete filter is not as transparent as the old fashioned fiberglass filters. How much will the Filtrete filter restrict the return air flow to the air handler in the attic?

How will using Filtrete filters impact the amount of cold air the AC unit will produce compared to using the older fiberglass see through filters?

Thank you very much!



These are a very common filter and should not restrict the air flow if replaced according to the suggested schedule. It depends of course on the structure also, how much air infiltration there is as to how quickly it will begin to clog and need replacement, but as you have seen, the fiberglass filters are see through. This means dust can also penetrate. They are designed to trap dirt, the pleated type will trap dust. If your alergies are severe enough, you may want to investigate an electronic air filter. I have an aunt that used one for 18 years from the day her unit was installed, and when it was replaced the indoor coil looked brand new! She did do the required maintenance of washing it as needed but it did an amazing job cleaning the air. Thanks J

Heating, Air Conditioning, Fridge, HVAC

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J Cook


With 25+ years experience, I am familiar with residential, commercial, and industrial HVAC equipment including but not limited to boilers, chillers, reciprocating and screw compressors. I am trained in all manners of control wiring.


I currently have three HVAC licenses and Refrigeration license by the State of North Carolina. I have been in this field for over twenty years. I have been a service technician for a contractor and also worked at a state college in the repair and maintenance of steam lines and equipment. I am currently the Building Maintenance Superintendent for a municipality.

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