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Air return makes too much noise, what should I do?

21593 Views 15 Replies 4 Participants Last post by  bigburb
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.
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So you're saying I can fit a 4" filter in a 1" grill? I saw 16x25x4 filters at the box store but I figured I needed a different grill to fit it.
The 15' run is located in the living room, which is a more "central" location to the house, but the one directly under the unit is in a hallway near bedrooms with no obstruction to the rest of the house. I found the Honeywell FC40R1060 which has a 1" lip so I can retrofit it into my existing opening. I might try this first... who knows if this is more than enough I might just block off the 15' run and use that space for something else.
Thermostat is directly above the hallway return, which is the one under the AC system.
What kind of insulation should I use to insulate the chase? I know standard fiberglass would probably be a no-no
I went ahead and ordered a 4" filter. It was only $10 more than the 2" filter but it will last another 6 months (supposedly). After installing it, I plan to block off the chase on the 15' run and see how it does.

I'd like to get some duct liner to quiet down the chase some, but dang its expensive! Is there anything cheaper out there?
No I just mean insulating between the 2x4's inside the chase.
Yes I plan on insulating the inside, I think I'm going use that cotton stuff I linked to. I may not have been clear enough in my terminology - my AC chase is a wall cavity, with a small plenum on top leading to the unit. The inside of the plenum is insulated already. What I proposed doing was lining the inside of the wall cavity, between the studs, with insulation. I'm not restricting it anymore than it already is, just going between the studs.
Installed the 4" thick filter yesterday, DEFINITELY cut down on the noise. No more whistling or loud suction noise. However I can still hear noise from the chase, so I still think I'm going to insulate it (will probably tackle that next month).

In the winter months, maybe when its cooler in the attic, I plan on suspending the handler from the roof rafters.
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