Wood stove backdrafting all of a sudden

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The clean out is 18” off basement floor, same level as stove door. Thimble is about 5 feet up on chimney...


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Then it could be possible when temps outside are mild and a competing appliance or exhaust fan is turned on. Everything that can be done to reduce this possibility should be considered. This could include outside air for a furnace or boiler and/or an HRV.
 
My assumption is that heating up the chimney better before shutting down for night would have made the difference. If I block the damper (or seal it) what would have happened instead of door opening?


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I'm not following. What damper is this?
 
Sorry, if I block (or seal) the clean out door....


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The cleanout door opening is going to rapidly cool down flue gases and exacerbate the situation. Is the latch broken? Normally it would take a strong bit of pressure to open it.

Is there an insulated stainless liner in the chimney?
 
The cleanout door opening is going to rapidly cool down flue gases and exacerbate the situation. Is the latch broken? Normally it would take a strong bit of pressure to open it.

Is there an insulated stainless liner in the chimney?

Yes insulated steel liner. Latch catches on but not by a lot.


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Yes insulated steel liner. Latch catches on but not by a lot.


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Thinking of taking a file to the latch and making it a bit deeper as to seat better


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I've had that happen the last 2 mornings. First morning smoke was pouring in the house and I could not get it to draft. I ended up pull clean out cap off bottom of T and it started drafting. I had a window opened up stairs and thought that was the problem but I made sure everything was closed up this morning and I was getting a little back draft. I checked draft with a lighter. I ended up lighting a piece of a starter stick and it took about 2 minutes but chimney started drafting. I'm not sure if it's outside pressure? I have never had this happen, which my stove has not been without a fire for a couple months until recently. The big lesson for me is to check my draft before lighting the fire.


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Yes insulated steel liner. Latch catches on but not by a lot.
If there is an insulated liner with a capped tee, how is it pressurizing the cleanout door? Is the top cap sealed?
 
If there is an insulated liner with a capped tee, how is it pressurizing the cleanout door? Is the top cap sealed?

“Capped tee” ??? The liner runs top to bottom and has a weather cap not sealed at top. The thimble “t” is about 4 feet up from clean out. I can’t recall but I think it standard type for liners. Insulated blanket around liner the tiles are not filled with insulation
 
“Capped tee” ??? The liner runs top to bottom and has a weather cap not sealed at top. The thimble “t” is about 4 feet up from clean out. I can’t recall but I think it standard type for liners. Insulated blanket around liner the tiles are not filled with insulation
You mentioned earlier that you pulled the cap from the tee and the draft improved.
I ended up pull clean out cap off bottom of T and it started drafting.
How did you do this if the cap on the tee is 4' up from the clean out?
 
You mentioned earlier that you pulled the cap from the tee and the draft improved.

How did you do this if the cap on the tee is 4' up from the clean out?

Two different people, slocum pulled the cap from “t” I don’t have a clean out “t” just the standard clean out chimney door which puffed open. [emoji6]


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Two different people, slocum pulled the cap from “t” I don’t have a clean out “t” just the standard clean out chimney door which puffed open. [emoji6]
o_O So is there a cap at the bottom end of your insulated stainless liner and a tee at the thimble?
 
Nope. No cap. The stainless liner ends at the clean out.

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I'd get a cap on the end of the liner. That could be the issue right there.
 
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I'd get a cap on the end of the liner. That could be the issue right there.

Ok so is it normal to put a cap on end of liner within the chimney? I’m guessing you just remove it for clean outs? Wonder why one wasn’t installed initially???


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Flue system for the stove should be tight with no air leaks. You want the draft to be pulling only from the stove. Leakage in the flue system weakens the draft and can excessively cool flue gases.
 
Makes sense. Thanks for staying with the post.... Guessing the bead of silicone around the clean out door may be easier to remove to clean out each year, and would seal the door from leaks and the occasional downdraft. Would love to hear if others have a cap at the bottom of liner with a cleanout door. My liner ends a bit up from the door so adding one now might be tricky.


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I would cap the end of the liner. Then the clean out door won't matter. There may be other leakage in the chimney that can feed air into the liner.
 
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