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So how many furnace filters do I really need?

Prevch
Prevch Member Posts: 106
edited August 2021 in A-C, Heat Pumps & Refrigeration
I have an air handler that we use mainly for air conditioning and sometimes for backup heat in the winter in case our boiler / propane acts up. The air box has a large drawer that originally was installed with a 20x24x4 filter. As you can see in the pic, the air handler has a slot for a 18x24x1 filter. Currently, I have a filter in both slots because I just presumed that's what I should do, but I never really bothered asking if I really should be using both. Obviously the more filters, the less airflow, but also the less garbage floating around my house presumably.

So, do I need both or is one sufficient? If I only need 1, is the 4 inch necessary or would 1 inch do it?

We do live in a rural area and we do get quite a bit of pollen in case that changes your potential input. If I go with just a single 1 inch filter, should I change it more frequently than if I went with a 4 inch?

Any opinions?


Comments

  • ratio
    ratio Member Posts: 3,777
    You only need one filter. I'd suggest using the 20x24 opening with a single 2" filter in it, unless you have allergies, then I'd go with the 4" filter. Pretty much what I do at home, except my filter box is 16x25x4.
  • Prevch
    Prevch Member Posts: 106
    ratio said:

    You only need one filter. I'd suggest using the 20x24 opening with a single 2" filter in it, unless you have allergies, then I'd go with the 4" filter. Pretty much what I do at home, except my filter box is 16x25x4.

    Yeah, all of us have pretty bad allergies, so I guess we will stick with the 4". Thanks for the response.

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