how many square inches should i have for a 3.5 ton heat pump.
I have 2 grills on same wall(corner), one is 20x20 the other 16x20, but they share the same box(metal) , as it goes into through the floor though the cut out is 14x21, which would be 294 sq in. now once it goes through the floor there is a large 22x22 that leads into thee AH, my question is the 14 x 21 BOOT in the floor....is that enough???how much do i need ???
THX again ..