OK to have an air return in unfinished basement?

Old 11-29-08, 06:51 AM
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OK to have an air return in unfinished basement?

It is ok to move an existing air return from finished side of a basement into the unfinished part? (unfinished basement has concrete floors, 4 ft crawl space used for storage that attaches to small laundry room - whole area is kept closed off from finished area).

We want to move it because it is so loud in the family room.

Thanks for your input!
Old 11-29-08, 10:58 AM
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There are several issues and I will probably only touch on a couple of them.
1. An air return is intended to balance the air flow from the supply side. With just a return in that space you will have a negative pressure that will draw in outside air. On the supply side, it will create a positive pressure that will force warm air out and where it goes out can sometimes cause condensation and related problems.

2. The air quality on the unfinished side is unknown, i.e. does that crawl area have a concrete floor or dirt. You stated the unfinished basement has a concrete floor, but not sure about the crawl space. Whatever is down there, you will be breathing. Especially if there is any exposed dirt.

The better answer might be to isolate the sound from that return. Do a search on "duct boards". these are rigid fiberglass boards used to make air ducts specifically to reduce the noise level. If it's too close to replace any length of tin, then build a baffel where the return enters the room. Obviously these suggestions may not fit your installation as I cannot see what you have, but they are thoughts.

Old 12-15-08, 10:19 PM
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agree that you do not want a cold air return in the unfinished bsmt.

There are other reasons as well--the air return should not be from any place in your home that is not heated--this causes your furnace to work harder to heat the air that will go into the heated areas-meaning higher heating bills, -this is why cold air returns for furnaces do not draw their air from the outside (unless, in very few specific incidences the outside air is literally "pre heated" before it goes to your furnace, which means a heater to heat the air for your heater...)

If your cold air return is loud--there IS a DEFINATE reason--IMHO usually it is NOT just loose duct work rattling, usually it means that your furnace is STARVING for air--meaning you need MORE air.

What this means is that either some air returns are closed or blocked (by furniture, carpet etc, or even--or that your existing return is too small, either the grill hole, the duct carrying the air--or both.

You can try a few things--1st, tighten up any rattles in the register/grill/duct work-Go through your house and make sure ALL cold air return grills are OPEN and NOT blocked in any way

-If this does nothing for the noise--find another room where you can add a return and duct it to the furnace--try the hottest room of the house...

Adding another air return would then lessen the pull of air from the noisy return--thus lessening the noise, and the draft.

Keep in mind--you can almost never have too many air returns--the more returns you have, the more balanced the heat in your home will be, the quieter each return will be.

Ideally, each room with a ducted heat register should also have a ducted cold air return-but many homes have only a central cold air return that is really big.
How many do you have?
Old 12-18-08, 08:51 AM
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I don't want to hijack this thread, but I wanted to address a couple of things that catia said. I'm not trying to start an argument, just wanted to make a few points.

You mentioned the furnace shouldn't draw in cold air. Our gas furnace has both an intake and an exhaust from/to the outside. I don't know what type of furnace it is without looking at it, but I would hope that it has some kind of preheater. Is there an easy way to tell?

Also the return in our master bedroom (every room has a return, which were apparently added when the furnce was replaced a few years ago) is right over the furnace in the basement, so it is the loudest one in the house. I would think that it's loud because of it's location, not because the furnace isn't getting enough air. I would like to quiet it down, but I wouldn't think it would be possible.
Old 12-18-08, 10:37 AM
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Croco, My gas forced air furnace also has two pvc pipes leading out a perimiter wall. One is an exhaust pipe. The other is not necessarily an intake pipe. It is there to help maintain a balanced pressure inside the house. Mine has a free floating weighted damper. If my home is completely sealed up and someone opens/closes a door to the outside, this damper swings to either draw air in to replace or let air out to displace. I was told that without this damper, it would be difficult to open/close doors leading to the outside. For whatever it's worth, this information is third hand.
Old 12-18-08, 10:49 AM
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Interesting. I'll have to take a look at mine. I assumed it was an intake, but then couldn't figure out why there were returns too.

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