How to increase air flow in cold air return?

Old 07-19-05, 05:32 AM
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How to increase air flow in cold air return?


My 2 story house has just 1 cold air return on each floor. There's a 22" x 22" wall grate in the dining room, which is directly above the furnace. There's also a 22" x 22" grate in the upstairs hallway ceiling, but there's only a 12" duct behind the grate that runs back to the chase. Needless to say not much air gets sucked out of the upstairs when either the furnace or AC is running. I tested it last night by trying to put 1 piece of tissue paper on the upstairs ceiling grate to see if there was enough suction to hold it there; there wasn't - it fell straight to the floor. I then blocked off half of the dining grate by putting a newspaper in over it and then tried the tissue paper again upstairs; this time is stayed there. Now I'm toying with the idea of permanently blocking off half of the downstairs return by painting a piece of cardboard black and attaching it to the backside of the grate. I couldn't do any harm to the furnace by doing this could I? My goal is to get more air returned from the second floor.

I also thought about putting some sort of suction fan behind the upstairs grate that would be wired to run only when the furnace blower is running. Does anybody even make such a thing? Any other ideas of how I can increase air return from the second floor? Thanks.

Old 07-19-05, 07:07 PM
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Return problem

I would try, on a temporary basis, blocking part of the downstairs return. You may find it is too much restriction & causes your A/C to freeze. Something like this is often trial & error. I don't know of anyone who makes a duct booster big enough for 12" duct.

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