Fireplace question

[sparticus]

Not exactly sure where this needed to go, I didnt see anyplace closer than this. I have a house with 2 fireplaces. 1 is in the basement and 1 directly above it in the living room. They share the same chimney but have seperate flues. My issue is the fireplace in the basement draws in smoke from the above fireplace even when it is not in use. The one in the basement (when it is being used)has a hard time getting the smoke to go up and out without spilling into the basement. Cracking open a window at the top of stairs seems to be the only thing that helps, but this seems counter productive. I'm sure these problems are related to each other. Any ideas as to what I can do to fix this? Right now I am forced to tape off the one in the basement and not use it. Thanks for any input you may have.

[mrcaptainbob]

Fireplace info...

It sounds like it needs an air source. Ideally would be to have one from the outside of the house directly into the firebox, near the bottom. If that's not possible, maybe providing a PVC run as inconspicuous as possible and it's opening be pointed near and at the fireplace opening. Unfortunately, you might need something at least 4" diameter to provide enough air flow. If aesthetics are important, maybe two 3", one on either side and hidden inside of a tasteful looking round or square column to coincide with the general decor in that area.....Also, provide a way to close them off when not in use.

[kactuskid]

I agree with Bob, you need to provide a combustion air source. You're experiancing stack effect and it can be overcome. Below are a couple of links that will help explain the phenomenum. You can also provide an air source in your basement by drilling a hole through your sill plate and installing a clothers dryer vent with ducting to a register grill mounted in the ceiling. Just open it when burning in the basement or instead of that you can open a basement window when you burn.

http://www.thechimneysweep.ca/2stackeffect.html

Possibly you're also experiancing some crossover since your flues are so close together.

http://www.masonrymagazine.com/6-03/fireplace1sb.html

[sparticus]

Thanks for the links! Its pretty much as I thought it was. My first fix has always been planned to be the extention of the upstairs stack. Looks like I am doomed for the time being to crack a window in the basement as venting will have to wait for the foreseeable future.