More in Fireplaces

Smoky Fireplaces

Two fireplaces sharing one chimney is a formula for smoke — and danger

Richard Trehewey holds a toilet

I have fireplaces on the first and second floors of my house. When I light the fireplace on the first floor, smoke pours out of the second floor fireplace. When I light the second floor fireplace, smoke comes out of the one on the first floor. I hired a chimney sweep to clean out the chimney. When I told him about this problem, he told me to block up the first floor fireplace — not a solution, in my opinion. Any ideas?

– Mark, Cranford, New Jersey


Richard Trethewey replies: I think the chimney sweep gave you the correct answer, even though it's not the one you wanted to hear. It sounds like the two fireplaces are sharing one chimney. Normally there would be individual flue pipes from each fireplace.
Could a double-wall stainless pipe be run from the top floor unit so that the common flue could be plugged off at the second floor? That would let the first-floor fireplace use the existing flue while the second floor uses the new metal chimney. Otherwise, take the sweep's advice and plug one of them. He's right. It's not safe.


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