Expert: James Ball - 2/8/2009

Question
 I have a two story colonial with a partial finished basement. I have one wood burning fireplace in the first floor living room. This room sits above the unfinished paert of the basement where my hot water heater and furnace are located. Every time I use my fireplace, the unfinished part of my basement gets very smokey and smells like smoke. I have separate flues for the fire place and furnace/water heater. I had them both swept and capped a month ago. Also, the doors to the ash traps are located on the wall in the unfinished part of the basement. what could be causing the smoke in my basement? Sometimes it isn't much smoke, but other times there is quite a bit of smoke and it leaks into the finished part of the basement.

Answer
Hello Ken, What is happening is you are getting Negative Pressure in your home, if 10 gallons of air is going up the fireplace chimney per minute then it needs 10 gallons of air per minute to feed it and it will pull the air from the path of least resistance from your home and in most cases it will pull that air down an other flue and with it smoke/odor the house needs make up air. Maybe open a window in the boiler/furnace room? Maybe extend one flue or the other to make it taller.
You could 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 they should be able to help.
James