Multiple flue chimney... Downdraft Problem


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Old 12-31-12, 12:48 PM
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Multiple flue chimney... Downdraft Problem

I have three clay flues exiting one exterior located chimney. One serves a woodstove on the main floor and the other two for a wood boiler & oil boiler respectively. Until recently (wood boiler install), a fire in the wood stove would downdraft through the cold flue of the wood boiler (not 100% installed).

The existing chimney has a single stainless steel cap. Would installing "dividers" between the exiting flues prevent this cross draft scenario?
 
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Old 12-31-12, 08:09 PM
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Hi sierradmax,
Tough one! With three that close together on an outside (cold) chimney it will be difficult to prevent the exhaust from one being pulled back down a backdraft in the others.

You said "until recently", is there still a problem? If the wood boiler install isn't complete, can you block that chimney for now? Once complete, do you think there will still be a problem?

To prevent the backdraft you need to warm the flue, block the path, or force air in the other direction (which would also warm the flue). There may be powered caps, but adapting one to your setup ???

Bud
 
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Old 01-02-13, 02:11 PM
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I've bagged & taped the barometric damper. I then had to stuff insulation in the wood boiler doors (door gasket is on order). That has controled the issue.

I think once I get the wood boiler up and running, I may have the same issue with smoke downdrafting into the oil boiler flue. Not 100% sure. I don't want to go the flue top damper route as I can only clean the flues from the roof.

Hopefully, dividers between the flues will work...
 
 

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