Smoke from basement fireplace


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Old 01-09-14, 08:29 AM
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Unhappy Smoke from basement fireplace

My home is seven years old with a woodburning fireplace on the main floor. It has a second fireplace in the basement that has never been used. At Thanksgiving, after lighting the wood in the main floor fireplace, the basement began to fill with smoke.

This was my first fire of the season. I have detected some smell in the basement in past years but this is the first time that smoke accumulated to the point that I had to immediately pull the burning logs from the main floor fireplace and toss them outside in the snow.

The flu in the basement is closed. My understanding is that there are parallel vents for these two fireplaces so my guess is that somehow the woodburning chimney smoke is being sucked back down the other vent and into my basement.

Help? I can't use my fireplace and I miss it.
 
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Old 01-09-14, 08:42 AM
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Welcome to the forum

If by "parallel vents" you mean there are two flues going all the way to the top of the chimney, then what is probably happening is cold air is down drafting the flue not in use. Outside chimneys are the worst. Even if you have the damper closed, they often do not completely close off the air path. A chimney cap et the top could stop that flow, but it would render the basement fireplace unusable.

If the two fireplaces are sharing one flue, that is another issue.

Bud
 
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Old 01-09-14, 02:38 PM
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Bud, thanks for your answer. Yes, I meant there are two side-by-side flues and the chimney is outside the house...and quite high. I sure hope there is a solution that doesn't disable the downstairs fireplace. Unlike the wood burning one upstairs, the downstairs one is gas only. Does that make a difference at all?
Magglio
 
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Old 01-09-14, 05:18 PM
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If you try running the gas fireplace first to warm up the chimney, that should stop the backdraft and hopefully the heat in the chimney from the wood fire will keep the gas flue warm for the rest of the upstairs fire. You may have to play with how long the gas unit needs to be run.

Extending the wood chimney or adding some type of deflector to keep the smoke away from the basement flue may help, but until that flue warms up it will be backdrafting.

Bud
 
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Old 01-10-14, 12:23 AM
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You should definitely have the wood-burning flue higher than the gas burning one. Also, a top-mounted damper (on the gas especially) damper will seal tighter than the damper in the firebox. Opening a window may also help significantly if the wood burning fireplace does not have an outside air duct. Last resort would be an inflatable balloon-type plug for the unused fireplace. You would have to turnoff the gas pilot but the balloon is removable when you want to use that fireplace.
 
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Old 01-10-14, 12:28 PM
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The flue for the downstairs fireplace was cold and down drafting, therefore pulling the smoke from the top of the chimney back into your home. To overcome a downdraft you have to heat up the flue by burning the fireplace. Once it's heated up, maybe 15 min, shut it down but don't close the flue. It should continue do draw warm air from your home up the flue for quite a while.

Alternatively you can install a lock top damper on the flue for the downstairs unit. They're very easy to install and will close the flue off completely from the top. You'll have no air movement through the flue, will help conserve energy and stop a down draft from happening.

I'd recommend installing the lock top damper on both flues, they really seal the flue tight compared to the damper in the fireplace itself.
 
 

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