Return Air in Basement


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Old 06-19-11, 11:27 AM
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Return Air in Basement

The basement of my home is completely below grade, so it's always naturally cool even on the hottest days. I'd like to tap in to this, and install a return air vent in the basement in order to "help out" the air conditioning. I'd like it to be closeable, as in the winter it would do the exact opposite with the heat. It seems pretty straightforward, as I could just install it in the return air duct that runs through the ceiling, but before I start, I'd like to know if there's any special precautions that I should be aware of. By doing this, would I throw off the balance of airflow? Should I be worried about ruining the integrity of the duct by cutting a hole in it? Anything else?
 
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Old 06-19-11, 03:05 PM
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Make sure the intake of the return as low as possible (just above the floor is best) to get the maximum benefit.

I have townhouse and the "basement" is finished, plus I have a wide open stairway between the two levels. The lower level has 2 return vents that are open at all times. It does wonders for the uniformity throughout the house. During the heating season, I run my variable speed fan constantly during the heating season and have in the auto during the AC season. I typically can maintain a maximum of 2 degrees F temperature difference. It is a big befit in heating the basement in the winter and cooling the upper level in the summer.

Dick
 
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Old 08-04-11, 05:01 PM
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I'd like to resurrect this thread, as I've been pondering this as well. Using today as an example...it's 80 deg outside, but basement is approx 65 deg.

The biggest problem I see with this (probably not unique to me) is my oil-fired boiler (which runs year-round for indirect WH) - I'm concerned about creating negative pressure in the basement and screwing up the boiler exhaust.

Experts...what say you?
 
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Old 08-04-11, 05:07 PM
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bnrup...Just curious: are you talking about sealing off the return from the conditioned space, and bringing in ONLY basement air? Or leaving the original return open, and "supplementing" it with basement air?

Again, I've also been thinking about this too, and every time I go down in to my nice cool basement, I think "Gee, all this cool air going to waste..."

Sorry to ramble on about this, but as I type, I think more about it...

What if: we simply disconnect and pull away the return air duct into the air handler from the conditioned space...and just leave it open? Would this avoid the negative pressure problem in the basement? (as air would still come down through the original return duct)
 
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Old 08-04-11, 05:56 PM
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A couple of cautions. Any return flow without a corresponding supply will create that pressure imbalance mentioned and both force good air out somewhere and pull bad air in somewhere else, probably the basement. Then there is the condensation issue with any outside air that finds its way into that cooler space. You might end up with a dehumidifier, assuming you are not running ac.

Adjusting supply and return registers for seasons is a common practice, but with each adjustment comes the need to maintain the proper air flow within the system.

Bud
 
 

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