I getting puffs of smoke out of the stove?

[AppalachianStan]

Look like I am have back puffs going on with my stove. Last night was the first fire went good cats fired off. but right now the stove is back puffing. The chimney was clean last weekend and the cats was not stop up. Temperature is 42* will this cause this?

 

[HotCoals]

Pressure differentials will do it.
Is there exhaust fans on anywhere when this happens?

 

[Sprinter]

Could be you tried to turn the air down too soon? That's what happened to me early last year on a warmish day.

How is your draft generally? How tall is your stack?

 

[begreen]

Maybe the wood is not too well seasoned or the air is being closed down too early?

 

[AppalachianStan]

The air was open all the way. The bypass was closed. the Stack is 15'. Stove top was 450* and stove pipe was 250*. This was at the end of the burn cycle. And no exhaust fans or dryer was running.

 

[HotCoals]

Do you have any cap on top?

 

[AppalachianStan]

Yes but it is clean and it has no screen in it.

 

[begreen]

Were any large exhaust devices running or turned on at that time? This would be like a combo of a range hood and a clothes dryer?

The backpuff occurred because the fire was smoldering and filling the stove with wood gases. Then a flame started and that ignited the gases. I suspect that the cat stalled, you opened up the air and that feed enough fresh air into the coals to light a flame a few minutes afterward. Does this sound plausible? If so, there was wood in the stove that still hadn't outgassed fully. This can happen when poorly seasoned wood is mixed in with the fuel load.

 

[HotCoals]

I dunno.
Seems like you are just getting a back draft down the chimney ..maybe because the chimney is to cold?
Much wind when it happened?

 

[HotCoals]

Tell us about your chimney.
Inside or out?
Liner?
Insulated?

 

[begreen]

If this is draft reversal that is an entirely different issue. Draft reversal is not the same as back puffing. But it seems unlikely for that to happen with a 250F flue.

 

[HotCoals]

If this is draft reversal that is an entirely different issue. Draft reversal is not the same as back puffing. But it seems unlikely for that to happen with a 250F flue.

I would think that a cooler chimney would be more prone to draft reversal...maybe that is what you're saying after i read that a second time..lol.

 

[begreen]

Yes, that's right. If this was a backpuff then it was caused by the ignition of unburnt woodgas.

 

[HotCoals]

Yes, that's right. If this was a backpuff then it was caused by the ignition of unburnt woodgas.

I concur 100%

 

[AppalachianStan]

Ya the stove was puffing smoke out in to the room. The one puff every once a while. The wind was not blowing. My chimney class A 8" by 15' tall

 

[begreen]

Were there any pieces of poorly seasoned wood in that loading?

 

[AppalachianStan]

Not sure the wood has split, stacked and drying for over a year.

 

[begreen]

It's just a theory. Damper wood would take longer to release its combustible gases.

 

[branchburner]

I only get backpuffing if I am burning something like pallet wood (too small/dry) and shut down the air too soon/too much. Too small/dry can be a problem as can too big/wet.

 

[Sprinter]

Is it possible that you had the air control turned down for a while and then turned it up later when the puffing started?

Not sure the wood has split, stacked and drying for over a year.

Depending on the species of wood, this may or may not be sufficient. I'm a big promoter of using a moisture meter to be sure of MC and would encourage you to get one, even if that turns out not to be a factor here.

 

[omnipotent]

I'll get a back puff on rare occasions based on wind direction. For me, if wind is coming out of east and fire isn't burning very hot a back puff can occur.....solution for me was to crack a window to equalize the pressure.....no more back puffs. Just a thought.

 

[Sprinter]

I'll get a back puff on rare occasions based on wind direction. For me, if wind is coming out of east and fire isn't burning very hot a back puff can occur.....solution for me was to crack a window to equalize the pressure.....no more back puffs. Just a thought.

That sounds more like a reversal of draft which would be technically different than backpuff if I understand them right. Still, I wonder if that isn't what's happening here since the results are pretty similar.

 

[begreen]

Both can lead to smoke backing up into the room but a backpuff is more dramatic as it is a mini-(or not so mini) explosion as the wood gases ignite.

 

[AppalachianStan]

It is 40* outside and it is hot in here. The cats are glowing. But Stove pipe is 250* and stove top is 400* on 3 splits. It may just be a draft thing. May need to add 3' of class A and if that does not work put a 6" liner in it.

 

[blades]

What is the internal measurements of the flue, sounds like it is masonry. Therefore likely too large in cross section to promote a positive draft even with temps stated, as the heat rise of flue exhaust gases are stalling due to moderate temps out side. Add some wind on a flue top that only has a top cover and no wind shields + low burn = recipe for back huffing