Stove backfire?

[Badfish740]

I had a weird thing happen this morning that I've never experienced in five years of burning wood. I had a good bed of coals from an all night burn as usual so I threw in four splits to get a fire going for the morning. I went upstairs to feed the dog, let him out, and get the coffee on. I went back down to the basement probably five minutes later and found the firebox full of thick smoke but no flames. Nothing was backing up into the house or anything, so I opened the door to let a little more air in (the draft was already all the way open)-none of the smoke came out, it just kind of hung in the firebox, not really going up the flue, but not backing up into the house either.

I closed the door figuring that the fire would get going eventually. When I did I heard a loud "PFFFFT!" A short blast of smoke shot out from the draft control and then flames began to appear in the firebox. I'm guessing that a bunch of wood gas had built up inside the firebox and it ignited, pressurizing it momentarily, but I can't figure out why it collected like that in the first place instead of venting up the flue like normal? I've never had a draft problem before. High barometric pressure maybe? Anyway, no big deal, no harm done, just scared the bejeezus out of me at 5:30 a.m. before I had my first swig of coffee...

 

[KodiakII]

Ever see the movie Backdraft? I think that is probably what happened to you. Combustible gases and smoke build until the ignition temperature is reached and oxygen is supplied (like when a door is opened) then...bammo!

 

[firefighterjake]

I had something similar happen to me when I tossed on some cardboard boxes on to a bed of coals and shut the firedoor . . . returned to find the firebox full of smoke, but no flames and then . . . WHUFFFFFFF! . . . big ol' "explosion" of fire . . . basically the cardboard was "off gassing" but there wasn't enough oxygen/heat to catch it on fire . . . and then the right ratio came along and blam-o. Nowadays I tend to be sure to give anything I toss on a bed of coals plenty of air if the bed of coals are relatively small and not putting out a lot of heat.

 

[begreen]

Search of backpuff. Seems like this has happened at least once to most seasoned wood burners. Consider yourself now initiated.

 

[toddnic]

Had that happen to me once in a similar circumstance. When I opened up the door on the stove to check it I ended up letting oxygen into the stove and when I closed the door....boom! Definitely scared me....I even had some smoke come out of the seams in the stove pipe (not the chimney). Thankfully no harm done other than needing to change my shorts

 

[begreen]

Happened to me too with the Castine under similar circumstances. It was not a pleasant experience. The stove let out a mighty whoomf.

 

[Warm_in_NH]

Had a small one two weeks ago. Thanks to this site I knew what happened as I had previously read a thread on it.

I hadn't put most of the screws in my pipe and read on here somewhere about the possibility of a back puff separating the pipe, so I put the rest of them in to be safe.

3 weeks later poof; same situation, just in the afternoon after being out and reloading on a bed of coals. Not big enough to blow pipe joints apart but enough to scare me and actually make the dog turn his head.

All in all, no negative side affects, and I'm much more likely to cracked open the door earlier now if I see a box full of smoke and no flame.
Good times.