I have a problem with smoke getting where it shouldn’t be. I have a chimney on my house, built 1954, with 3 flues, one for the furnace,disused; one for basement and one for main floor. The problem is when the main floor fire is used I get a strong smell of burnt wood in the basement. The top nine courses of the stack have been rebuilt. The flues are made from a terracotta type tile material and are about 8″ square, and the flues stick about 6 ins above the top of the chimney. Any ideas how to solve the problem. Both flues are unobstructed. Would extending one flue higher than the other work. Is the problem lack of airflow?. The windows in the house were replaced. Any advice would be appreciated. Sorry if I have used different words, I am English.
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Dear Brit,
Great question. You can see this effect all over if you look.
The problem is that you actually have 4 flues. The forth is an accidental passage that allows warm air from inside the house to flow into the attic and outdoors. This acts as a passive exhaust device.
This creates a vacuum inside that s ucks outdoor air and it may be why you had your windows replaced. They probably drafted all the time.
The vacuum is strongest at the lowest point in the house, the basement. So the flue down there is sucking outside air too. The place it gets that air happens to be adjacent to a source of smoke. So down it comes.
Block the accidental flue and the smoke smell will stop. The house will become much more habitable in other ways as well.
Regards, Fred
[email protected]
Thanks for the info. I think I understand what you are saying. In this instance the fourth flue would be the stairway to the attic and then out. That door is as tight as we can get it. Sealed on all four sides because of the drafts down from the attic. Yes sealed on the floor, with a tight sweep. The reason the windows were replaced is the old ones were single pane. Now we are double glazed, also helps with the sound from the flight path. I agree the old ones would have leaked. Any way thanks for the info.
Fred, could the smoke be getting s ucked down the unused furnace flue if it is unblocked or the basement fireplace flue if the damper is open or not tight enough?
Edited 4/5/2002 10:15:38 PM ET by WFLATHER
Brit,
You need an outside source of combustion air since that roaring fire is pulling the air it needs down the flue that leads to the basement. Crack a window before you light the next fire to test.
KK