What causes this temperature spike

[tjl147]

Have an 80s Woodstock Palladian. Got it nice into the burn zone tonight and added a big log to the hot bed of coals. Shut her down for the night as per normal.

A few minutes later I notice the temp (indicator is on the pipe) went up quite a bit, which has never happened before. It then quickly went into overfire.

I took out the large log (glad I had welders gloves handy) and tossed it into a snow bank. Looked up and chimney had no flame or unusual smoke, so no obvious sign of a chimney fire. Left hot coals in and stove has settled.

any ideas on what happened? I actually just took the pipe s apart this morning, and felt around where the pipe meets the chimney and did not notice creosote issues. Pipe and stove were put together and a fire burned all day. Creosote in pipe was normal, at least bywhat I usually see.

but I can only guess I had a fire somewhere in the pipe or chimney?

 

[begreen]

Was the bypass closed shortly after putting in the fresh wood? Just a guess, the cat was overwhelmed with a big blast of unburnt wood smoke due to the large log on hot coals and the wood gases ignited (secondary combustion) in the stovepipe?

 

[tjl147]

Thanks for the response. That makes some sense.
I am also wondering if there was another factor. Stove had not been used until the evening, and it was around 0 degrees last night. Stove vents into a masonry chimney that is 8x12 inches (I know, huge).
Even though I only burn seasoned hard wood could a sudden plug of creosote develop? Takes a while to get that huge chimney warm.

I will take it apart again to investigate. Good news is temp did not get that crazy hot and I caught it in time.