Return filter

[butneway]

Should filters be used at both the return and the air handler? Several friends, not pros, have said yes and no. I have always used one just in the return.

[tn a/c man]

I would prefer only having one pleated filter made by 3m at the return grille. Your best bet would be going with a media filter only at the furnace,you only have to replace yearly,there are several brands,I would recommend a spacegaurd,made by aprilaire,you have to have them installed by a heating and air onditioning contractor.

[hivacer]

No it should be one or the other. If you have just one return grille it is common to place a filter there. If you have multiple grilles it will likely be in at the air handler.
Either way, the job of your filter is to supply the furnace with clean filtered air. More than one filter could create more of a pressure drop than is desired.

[amickracing]

I prefer to have them as close to the unit as possibly, simply to keep nasty stuff out that will find it's way into a poorly sealed system. For what it's worth, even a system that is sealed pretty good can still get some crap in it.

You "could" have 2 filters (one on each end), but the system would have be to designed for that, and most are lucky to be designed properly for 1 filter.

[butneway]

Thanks for the replys, appreciate the help!