Expert: James Ball - 11/22/2009

Question
I have a wood burning fireplace that has intemittent problems with emitting smoke and odor into the house. Sometimes we can light a fire and there is no problems, the next time it may emit a strong smoke odor into the house as well as smoke. The chimney is clean and clear and it has a clean out at the bottom that we keep cleaned. There is no cap on the chimney and it is a double chimney as well but the other flue is not currently being used as a ventless gas furnace was installed. There does not seem to be any diffence on how windy it is outside either. Just can't seem to figure out what the problem is.  The house by the way was built in the late 60's and there is no other source for air flow other than the opening in the front.

Answer
Hello Laurie, 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) your house is a better chimney than your chimney. Also kitchen/bathroom exhaust fans, cloths 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 area’s. A top mount damper cap might help if closed the next day after the fire is out.
Trail and error until you get this fireplace to work for you, maybe close off the room from the rest of the house to use it (close doors)
Or it could be dirty? 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