My wife is watching a stupid tv show so Im watching the woodstove and its very interesting. All of a sudden every so often I there is a whoosh and an eruption of flames that roll around the firebox. Its really cool looking but Im wondering is this backpuffing or just some odd phenomenon of the stove Ive never noticed before.
Your stove doesn't have enough O2 for combustion of the gases. Once there is enough O2 the accumulated gases ignite and you get a cool show. Pretty sure it's backpuffing.
Ohiostihl nailed it. When this happens here, its just a matter of time until full secondaries end up kicking in with the castine. There is also times (rare) when the puff is strong enough to leave a light wood smoke scent in the house.
I have trouble with ours in wind gusts, have to almost shut down the intake (below #1) so the wind doesnt suck all the heat & wood out too fast. Tough because its more gusts than calm, if I open the intake up again to I forget and the logs are all ash by the next time I check.
I have this same thing happen in my Answer from time to time. I've mostly solved it by installing a stove pipe damper and shutting that down about 3/4 before I start limiting the intake air, right after a reload. I would like to believe that I'm getting a better overall gas ignition, holding them in there longer with plenty of O2 and then when everything looks decently charred I throw the pipe damper completely closed (which is not actually totally blocking the pipe because of the way it's made) and pull the air control almost all the way closed...boom, nearly instantaneous rolling secondaries. Of course ymmv!
How far was the stove into the burn? I've found keeping a small amount of flame in the box is a big help, shutting the air down in increments and knowing how far to close it based on outside temperatures is key with a fireview. Currently in this cold snap im settled in at 0 to .25 draft. Zero degree temps or less outside. If its in the 20-40 degrees range I usually run .75. Another thing to do is make sure all the wood is charred, I usually have a bit of trouble charring the very front logs due to the bypass being at the back, most of the flame is sucked up there and prevents the top logs from charring, so I run the stove on bypass and keep stepping the air down and hold the stack temps down until everything is charred and then engage at that number. (Usually .75)
Matt you can definitely get a back puff in the Fireview. We've had 2 that I remember and they happened when the weather was relatively warm and not a lot of fire in the stove. No harm done but we definitely could smell smoke when it happened. But like jdonna stated, we cured it by giving it a bit more air. Our normal setting is about .75 but in warmer weather (above 25) then we typically have the setting at 1 and occasionally 1 1/4. That takes care of any back puffing.
I was towards the end of the burn it was just three medium sized pieces of pine. I think I had the air shut down to far as it was warm outside (low 50s) and windy. I opened the air some more and it stopped. I had an obvious back puff a couple years ago it was very violent it rattled the stove and puffed the lid up and blew smoke out that was when I was still pretty new with the stove and it scared me a little this one last night was just really cool to watch but something told me that it wasnt right.
The end of the burn cycle is usually when I get a backpuff as you described, either from the back pieces not being charred enough and sudden off gassing as the logs lite up or the stack cooling, losing draft and note quite enough air for the load. It's also possible to have a down draft a gulp of air from your stack if the flue reverses. I put my manometer probe in to see and never saw any positive pressure on my stack but I have heard of it happening.
