Return air box, grill size, etc

[autx790]

I am trying to move the return air location for my house to make room for stairs (converting a duplex). I basically want to move it across the room into what will be the pantry, but trying to minimize the space it will take up. I have a 3.5 ton unit for about 1050 sqft and before the filter they were using was a 14x24. I have the old air return duct under the house but it's very large and I don't really want to run that up throught the floor in the pantry. I'm thinking i'll need a larger filter (20x20 or 24x24 or something in that range) but not quite sure how to build the return box or the best way to run ducting to it to minimize the space it takes up. Any suggestions? I'll try to include some photos later.

[Smooky]

In most cases a 14 inch wide filter housing and duct works good because everything fits between the wall studs and floor joist. You could split the return and have 2 returns instead of one large one. You could put one under the stairs too. Another option would be to put louvered doors on the pantry and build the return in the pantry without coming through the wall.

[autx790]

Hey, thanks for the response. Would a 14" housing provide enough air flow though? That's what they had, but I don't trust anything that was done on this house before i bought it. I would be nice if i can fit it between the framing and i think it's better to put it higher than lower (there's a fireplace 2ft away that i may use one day) so i'd have to run a bulk head up along the wall in the pantry. I think the trunk under the house is at least 18", would I have to run that all the way to the box? I'm guessing two smaller ducts would be easier, but i'm not sure how to guage the size based on the filter. Does the duct have to match the squar inches of the filter?

I agree with you that it may be better to split it up and have two filters. Under the stairs will be storage (which is already limited in the house) but if it's a smaller grill that might be an option.