I have a 4 ton AC system with 2 16x25 returns. One is located directly under the AC and is attached to the plenum, the other is located about 15 feet away and is attached via about a 10" duct. The closer one makes a lot of noise and catches most of the dust... the farther one has hardly any suction (I can usually go about 6 months b/t filter changes). I know I need to get more filter area somehow, I had three theories on what to do, but would like input:
1. Enlarge the current opening to 16x32, this would yield 175 sq in more intake space.
2. The chase directly under the plenum is on a hallway corner, I could install another 12x24 return grill on the adjacent wall that would yield 288 sq in. However I wasn't sure if it would be "aesthetically pleasing" to have a return on either side of a corner.
3. I can enlarge the return duct from the furthest chase to 12", I'm not sure if this would have enough effect to make a difference though.