Scary event this morning... whats wrong?

[jhizzle207]

I was woken this morning to what google would seem to indicate is a "hot backdraft"

The stove was banging, I actually thought it was someone knocking on the glass of the back door. When I went to look out the door, another "knock" and a puff of smoke came out around the door gasket from the stove. Assuming it was a log rolling forward (my wife would have filled it an hour earlier on her way out to work), I grabbed the tool and open the door.... and nearly lost my eyebrows... a substantial explosion of flame happened when I opened the door.

Two logs were about half spent with a nice bed of coals. This was well seasoned hardwood. The stove is a Lopi Liberty with double-walled pipe going to a lined masonry chimney (single story). It was pretty mild this morning, likely high-20's during the event. As I said, the wife would have dampered it an hour or so before this occurred, so it's not like it was ripping and then squelched.

We've been here a little over 2 years and use the stove exclusively for heat and have never had or noticed this problem (and I work from home). We don't have much in the way of meaningful draft issues, cold starts aren't too painful. Is this an anomaly or is there some steps I can take? I'm afraid the banging I was hearing could damage the glass/pipe or worse when we're not home and make us a statistic.

 

[defiant3]

If it happens again try opening the primary air slightly. This happens occasionally in modern stoves when conditions are just right. Someone perhaps can explain more thoroughly but it's like all the oxygen burns at once causing a little explosion. If there's a steady stream of primary air it doesn't happen, but may with the air control way down and almost always with really dry wood. Like REALLY dry.

 

[Espartaco]

I've gotten in the habit of opening my primary air along with my damper before I open the door to stop any smoke spillage. I also just crack to door open, wait 30 seconds then slowly open the door fully.

 

[VirginiaIron]

This might help with any anxiety about the glass in the door

https://chimneysweeponline.com/howindow.htm

 

[Attaboy]

Could have been a negative pressure situation and you let oxygen in too quickly.

 

[oconnor]

Chimney fire? The knocking as the chimney overdrive the flue gases, then the flash over when you opened the door says to me that the stove wanted more air and jumped for it when you opened it.

 

[begreen]

Sounds more like backpuffing. Perhaps due to smoldering wood on hot coals that had the air turned down too soon? This can happen when the firebox fills up with volatile wood smoke, then a small flame appears and it ignites all that accumulated wood gas. Poorly seasoned wood can also cause this phenomenon if not allowed to ignite fully before closing the stove door or closing down the air.