Puffback

[enchant]

Check out this video. It's my 1.5 year old Jotul 400F Castine.



You can see the regular flashups due to the unburned gasses collecting and ultimately igniting. But there's no puffback here. All the smoke is contained, and this happens on a daily basis. There are long periods of time I'm not watching the stove, so I wouldn't be surprised if it happens more often than I know.

I had a fire going a few days ago and was in the basement doing some work. When I came up, there was a very strong smell of smoke in the air. I went to the stove and watched it for a bit. These mini-explosions were happening, but perhaps they were more intense, because smoke was squirting out of the pipe seams. I immediately opened the vent to get the fire flaming, and the problem stopped.

But this is the first and only time I've seen this since I installed the stove. Last year I was forced to burn a mixture of dry and under-seasoned wood. This year, that wood is over 20 months old, so that shouldn't be a problem. To be honest, I can't remember what the temperature was outside. Perhaps it was up into the 40's. I also don't remember if I'd let that load get well burning before closing down the damper.

Is one of those two factors the likely cause of the smoke? Also, despite the entertainment value, is it bad for that oscillating gas ignition, even if there is no smoke coming in?

 

[firefighterjake]

Open up the air control just a dite and you should alleviate your issue . . . in a way what you're seeing is a miniature backdraft. The fire doesn't have enough oxygen so it dies down but the combustible gases continue to build up until finally enough oxygen enters the firebox at which point it "explodes" into flames.

By opening up the air control just a bit you should allow enough oxygen to enter the firebox to get a sustained secondary fire . . . and no mini-backdrafts.

 

[Doc C]

1. Make sure chimney is clean
2. Crack a window
3. Too warm outside to draft well

If any of these are the problem then you have your solution.

Fix for chimney would be to clean it. Fix for supplemental air or temp outside would be as Jake said Crack your damper, add extra air near your stove, or Crack the window.

 

[begreen]

The Castine's shallow firebox needs good draft and dry wood. Many years agoI had the mother of all puffbacks in the F400. The wood was semi-damp and I was over eager in shutting down the air too soon. The flames died down to nothing and the wood smoldered, building up smoke. Then a flame appeared and ignited the unburnt wood gases with a mighty whump! Smoke poured out of every seam and I was so thankful for those 3 screws per pipe joint. That only happened once. It was a strong lesson in always provide the fire with enough air to avoid smoldering and always burn dry wood.

What's happening in the video looks ok. The wood has charred thoroughly and outgassing has slowed down. If this was at the early stage of a fire, it would be more risky. The solution is give the fire a bit more air at least until the wood reaches the more advanced stage of the burn.

 

[enchant]

Thanks. My primary concern was the few times I load up the wood and leave it to burn overnight. But I only do that when the temperature gets down under 15 or so. So I'll be sure to get it burning well for a while before I go to bed and damp it down.