Furnace Filter Location?

[Art]

Looking for input on the "best" location for a furnace filter. Two options - at the main air intake in the ceiling or at the cold air return at the furnace?

Thanks . Art

[Joseph Meehan]

Describe "main" If it is main because it is one of several, then your only good choice is at the furnace. You want to filter ALL the air entering the furnace.

That filter is there to protect the furnace, not to provide you with clean air. It may do both, but the primary purpose is to keep the dust out of the furnance/AC and keep it running longer. Putting just one filter on one of more than one air returns will allow un-filtered air though to the furnace.