Trying to Understand How Top Sealing Damper Would Work With Chimney With Two Flues

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Small Law Survivor
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Trying to Understand How Top Sealing Damper Would Work With Chimney With Two Flues

Post by Small Law Survivor » Thu Nov 08, 2018 8:59 am

We have a chimney with two flues - one from a first floor fireplace, and one that goes down to a free standing wood stove directly below the fireplace, in the basement. The wood stove sits on a raised brick hearth and is connected to the flue by a stovepipe into the wall.

There is no cap on this chimney. The first floor section of the chimney is on an outside wall.

The problem I'm trying to solve is that the cold air that enters this chimney in the winter radiates into the house from the chimney. What makes this worse is that the first floor has a ceiling two stories high, so there is a large surface area exposed to the interior of the house on the first floor. In other words, the column of cold air in the flues is two stories high.

A chimney sweep recommended a top sealing damper, and this strikes me as a good idea. However, this requires a chain to drop down into the fireplace that would be used to open/close the damper. And, according to to the chimney sweep, that would not work with the flue to the basement/wood stove, since there's no way to install an open/close chain there.

The chimney sweep's conclusion: install the top damper on the flue that goes to the first-floor fireplace, but do nothing with the flue to the basement/wood stove - you have to live with that as is.

My questions: does this conclusion sound reasonable? Isn't there a way to attach a top damper to the chimney in such a way that it would cover both flues and be opened/close with the chain to the first floor chimney (chimney sweep says no). Is there another solution to this problem?

Thanks in advance.
68 yrs, semi-retired lawyer, 50/40/10 s/b/c, 70/30 dom/int'l. Plan: 4% WR until age 70, 3% when social security kicks in. Boglehead since day 1 (and M* pre-BH site) under diff names

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Re: Trying to Understand How Top Sealing Damper Would Work With Chimney With Two Flues

Post by sjt » Thu Nov 08, 2018 9:36 am

I wonder if you could install some sort of butterfly valve just behind the wood stove to prevent cold air from getting into the stove, but the exhaust pipe would still fill with cold air. Do you use the stove? Of so, it should be filled with warm air (during use), if not - perhaps cap it off at the top and be sure never to use it?
"The one who covets is the poorer man, | For he would have that which he never can; | But he who doesn't have and doesn't crave | Is rich, though you may hold him but a knave." - Wife of Bath tale

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