Expert: James Ball - 12/31/2010

Question
Hello,

I have a basic ranch style home with a 3 flue chimney.  The chimney caters to the main floor fireplace, a fireplace in the basement and the boiler exhaust.
The issue is that the main floor fireplace has a wood burning insert with the required stove pipe running up the chimney flue with a rain cap.  
When we burn in this insert the basement used to get a fair amount of visible smoke in it.  Figuring that it was somehow coming in from the basement fireplace (I'm sure that it shouldn't)I put plastic over the fireplace opening.  The cleared up the majority of the smoke but the basement constantly reeks of smoke when burning in the insert.
Since the fireplace in the basement is covered with plastic could the smoke odor be coming from the furnace draft regulator?  If so, how would this happen, and if it is unlikely, where do I check next?
Thanks for any help!

Rich

Answer
Hello Rich, When you have 2 fireplaces the one you are using needs to draft, lets say 10 gallons of air per minute, then it needs 10 gallons of air per minute from the home and in most cases it will pull that air down an other fireplace flue this is called “make up air”, 1st make sure the damper is closed on the un used fireplace, close off doors to the other fireplace area (basement doors), leave a window open on the lower level, install top mount damper cap on the down stairs fireplace.
There are many other reasons a fireplace will smoke, negative pressure, that is hot air rising in your home (and getting out through the attic vents, doors, lights) your house is a better chimney than your chimney. Also kitchen/bathroom exhaust fans, Radon systems, cloths dryers and the furnace all take house air out of the house (mechanical negative pressure)

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, they should be able to help.
Hope this helps
Happy Holidays
James