Need advice on cold air return

mrlouie

I recently purchased a home, and in the process of doing a kitchen remodel I needed to change some of the framing. The problem is that the old cold air returns for the second floor were run between the wall studs, with no duct work and sealed very poorly, in the exact two spots where I added headers. I want to replace the two cold air returns that I have now blocked off with 6" oval returns in other spots.

Question #1 is will two 6" oval cold air returns be enough for approximately 400 square feet (2 bedrooms/bathroom/hallway) of space? I have a vaulted ceiling and a lot of the heat gets funneled upstairs by convection, if that makes a difference. There are 3 heat ducts supplying this same space, all are 6" oval. I plan to damper these as even with only 2 currently hooked up it's too warm upstairs vs. downstairs.

Question #2 is how far apart should a cold air return be from a heat register? One of the few spots I can place a new cold air return is about 5 feet from a window that has a heat register below it. Is this too close?

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mrlouie

No one liked my nifty drawing? At least call me a moron for doing it backwards!

beenthere

The general position of the returns is fine.
but. You'll need more then just 2-6" ovals. if you want it to cool ok in summer.

3 or 4-7" ovals.

mrlouie

Thanks for your reply, the help is appreciated. Would using two 3 1/4" x 14" ducts be any better? I've read that rectangular ducts can be bad for flow as well though... it's just that I am so very limited on walls that aren't either exterior walls, or load bearing interior walls. I'm not sure where I could run a 3rd or 4th return through the framing unless I did 2 returns side by side in the room on the left in my picture.

beenthere

2 returns side by side is fine. And is how it is often done in the hallways of the second floor, and or master bedrooms.

3¼X14 is better then 6" oval. But only 2 of them won't be enough either. In the summer.