Expert: James Ball - 12/6/2009

Question
We have 2 fireplaces and the chimneys are located next to each other.  Both have been recently cleaned and we just put on metal caps for the first time, as they were recommended by our chimney sweep.  One fireplace is on the main level and one is in the basement.  We also recently removed glass doors from the basement fireplace.  Now when we light a fire in the family room, the basement gets smokey.  What should we do???

Answer
Hello Candice, What is happening is you are getting Negative Pressure in your home (house stack effect) that is hot air rising in your home (and getting out through the attic vents, doors, lights, in this case it is another fireplace (is it closed?)) your house is a better chimney than your chimney. Also kitchen/bathroom exhaust fans, clothes dryers, Radon systems and the boiler/furnace all take house air out of the house (mechanical negative pressure) your house needs make up air, perhaps an open window in the basement? Or stop the air from getting out the attic and other areas.
You could also try a top mount damper cap on both fireplaces, they close on top with a cable coming down the inside of the chimney to open and close the top, this way one fireplace would not draw air down the other to feed it self with the other close.
I would have a local Certified Chimney Sweep (www.csia.org, there you can look up by zip code to find one near you) take a first hand look at what you have.
James