I have a prefabed fireplace that can be either gas (current setup) or wood. I'd like to convert it to wood (gas assist), but am being told that I've got a severe downdraft, and would either need a chimney extension or a chimney fan.

Right now, the chimney extends ~4-5' above the roof, but is adjacent to a wall (I live in a converted factory, the fireplace is part of a one-story part of the house, adjacent to a 2-story part). Extending it to fit the 10' / 2' rule would mean something like a 10' vertical extension, which is probably expensive. Chimney fans are ridiculously expensive too (cheapest I've seen online is $1K, contractor quoted me $2.2K).

Are there other options?

1 Answer 1


The first thing to check is. Do you have a backflow preventing Cowl on the Chimney. These are quite effective in preventing backflow into your chimney.

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But the real problem is that you are getting a high pressure against your second story wall which is butting against your chimney pipe. Its a natural progression that the wind buffeting the wall will want to flow down the chimney. Besides the chimney extension to a point outside of the high pressure zones created by the building structure. you could possibly put an elbow on the current chimney to move as far away from the wall as possible.

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