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Discussion Starter · #1 · (Edited)
I am confused about code and best practices for returning cold air from the basement. I have an unfinished laundry/furnace/water heater room (large) and a finished game room (also large). The laundry room is cold. The furnace and water heater are vented through the chimney. Dryer is vented outside. The room has a portable dehumidifier. The furnace and water heater are together.

Can I put a return in the furnace/laundry room?

I know code seems to say it has to be 10' from the furnace. I could put one along the return ductwork in the ceiling (see the attached picture), but that won't suck the cold air as well as one along the floor.

I could put a return on the other side of the wall in the game room, but why is this so different than putting it in the furnace room? Both will ultimately suck the same basement air. And it will suck less cold air.

Surely this is a solved problem?

It seems wasteful to not recirculate all that cold air.

My friends and I have been debating this video:

I think this is against code and a bad idea.

Thanks so much in advance!

 

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The furnace and laundry room, being enclosed will more readily go into enough of a negative pressure with a return to cause water heater to backdraft. (and furnace if it's natural draft)


It's bad enough to have a drier in there - it may be common but in some applications can cause the same problem.

Add return only to the rest of the basement.



If you close your basement vents in the cooling season, you'll have to have a return path to the basement for air to get in from the upper floors -> if there's a door which is left closed, you can cut a hole in it and put grills in both sides.

Negative pressure, aside from causing back-drafting can increase air leakage into the basement.

After adding return, do this test with all basement vents closed, water heater furnace (in heat mode) and drier running at the same time: http://waterheatertimer.org/images/Test-water-heater-vent-400.jpg
 

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Our home's furnace, located in the basement laundry room, had a cold are return installed in the return plenum. An HVAC guy recommended I block it, which I did. When the furnace was replaced, several years later, the new plenum contained no cold air return vent.
 
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