Smoke Coming Down Second Flue

Berlin · Post by **Berlin** » Wed. Dec. 26, 2012 12:43 am

cap didn't seal tightly. Seen it a bunch. closing of the cap reduced the velocity of air going up the stack to the point where the negative pressure in the basement and the warm air around the poorly sealed top damper allowed the conditions for draft reversal. Not uncommon, just weird if you haven't seen it before.

rockwood · Post by **rockwood** » Wed. Dec. 26, 2012 1:25 pm

That was my first thought too...

rockwood wrote:When you opened the cap on the downstairs fireplace it might have let the chimney start drafting on it's own but when it was closed it might have had a slight downdraft going because it was cool pulling some smoke down...?

But I'm surprised that the draft would instantly reverse when the cap was opened. He also said it started coming into the basement again when he closed it (he only did this once if I understand correctly)....I don't think I ever seen a chimney reverse draft back and forth in such a short time like that, especially on an "interior of the house" chimney.

oilman · Post by **oilman** » Wed. Dec. 26, 2012 9:15 pm

Berlin wrote:cap didn't seal tightly. Seen it a bunch. closing of the cap reduced the velocity of air going up the stack to the point where the negative pressure in the basement and the warm air around the poorly sealed top damper allowed the conditions for draft reversal. Not uncommon, just weird if you haven't seen it before.

I would have to agree with this. I can't think of a product out there that would 100% seal a s/s liner, they work better with tiles. Top dampers can be troublesome at any rate.