I've been lurking around the forums for a while and thought I'd finally sign up and ask a question.

We just moved into our new house, and I'm a little confused. I've never lived in a house that has air returns on the floor. There's 2 of them in the house -- one in the hallway and one in the dining room.

My air handler is in the basement, and there's a filter on the side of it, which I expected. However, I'm confused as to how any air is getting filtered from those floor returns, since you can see in the basement that the ducts go from the floor, straight into the handler.

Forgive me if this is a stupid question (since I don't really fully understand how these things work anyway), but if there's 3 ways for air to get into the handler, but a filter on only one of those (on the side of the handler), isn't only 1/3 of the air going in getting filtered? Should there be filters on those returns, as well?

 

The air needs to be filtered at the unit or at the return grills

 

Yes, as airman said, all of the air needs to be filtered.

 

So in my two returns in the floor, I need to put a filter in there?

 

Somewhere along the way, hard to say where without seeing it. You're sure they don't have a filter somewhere before they dump into the furnace?

 

All I've been able to find is the filter on the side of the air handler, but now that I'm sitting here at work (and thus, unable to actually look at the darn thing, I'm beginning to think that maybe I misread how this thing is working, and I need to take another look when I get home.

I just realized that the filter goes into the air handler, but does not have a side exposed to the exterior, so I'm betting I completely misread this whole thing and that those ducts are connected BEFORE the handler, and all the air passes through that one filter.

Long story short: I might be dumb

 

You might be ignorant but that's completely curable, we do it here all the time