Expert: James Ball - 12/27/2010

Question
Hello. I have an 8 year old 3-story home with superior heatform fireplaces on the ground and second floor. Each has a problem with reverse draft but the problem is more severe on the ground level. I don't believe it is a negative pressure problem in the house as I can easily overcome the reverse draft with a couple candles. The second floor stack is terminated about 16 inches higher than the lower level but each one is capable of drawing smoke from the other when only one is in use. I don't think I can change the physics of a stack full of cold air pushing down on an ill fitting damper so I need an effective and convenient way to seal an unused flue. I'm considering a spring loaded lid that is operated by a chain fed through the flue or an inflatable plug just below the damper. The inflatable plug seems like it would offer the best seal. Can you please share your opinion regarding these methods and possibly recommend some specific products?

Thanks in advance for considering my question.

Warm regards,
Brett

Answer
Hello Brett, yes you do have a negative pressure issue (not just from the fireplaces but also the home it self) and the fireplaces are also contributing, kitchen/bathroom exhaust fans cloths dryers, boiler/furnace running and so one.
as far as sealing the fireplace flue you are not using maybe the plug would work best for you (I have never used them)
Good Luck and happy Holidays
James