REGENCY F3100L stove pipe question

[Gwilkrrs]

New homeowner, new wood burner. Recently had issues and had a sweep come out- cleaned all up well and smoke issues went away, got a clean inspection report. 6” stove pipe stuffed into an 8” chimney pipe ( SS smooth liner pipe) the sweep packed the transition with insulation and said I could get a transition pipe if I wanted. Tonight we woke up to smoke smell- I went and looked and the stove air was all the way in (choked off for the night), I could see red coals and logs and then the stove huffed and “breathed” a big breath and the smoke puffed out of the pipe joint after the horizontal 90
Now looking at the pipes it seems like they are “lapped” wrong ?
I pulled the air chamber out and immediately had a fire that spiked the temp and had to push back in to choke off and the fire still roared for a bit till it calmed down.
The stove never puffed thru the pipes again.

 

[BigJ273]

What do u mean by “lapped wrong?”

 

[stoveliker]

likely he means the crimped end up?

 

[Gwilkrrs]

The 90 goes over the horizontal pipe instead of in it. I figured flow like drain pipe where the pipe always goes in not over so no leakage? This isn’t an issue normally so maybe not but when it was huffing last night the seam is where the smoke came from.
Obviously this isn’t a normal operating issue but it happened.
She had put logs left to right and then put a couple on to front to back, had them burn for 20 min then chocked the air rod down closed for the night- then later when the flames stopped the huffing happened

 

[BigJ273]

It’s supposed to be that way. The theory being that allows creosote to run back into the stove if it drips

 

[Gwilkrrs]

Ahhhh now that makes sense.

So I just need to understand why it was huffing and puffing so it doesn’t do it again…….

Thanks. I feel better now actually

 

[stoveliker]

What you experienced was a back-puff.
This can happen when one burns a load hot enough to generate a lot of gases (that still need to be combusted fully), and then too aggressively chokes the fire. Then there's not enough oxygen to burn all gases, and not enough air flow to wash them out of the flue (which would lead to a dirty flue, creosote deposits...), leading to an accumulation of these combustible gases in your stove.
Then if for some reason enough air (oxygen) does come in (e.g. with a wind gust outside sucking more on the flue), the mixture of gases in the stove can be such that a sudden ignition happens. I.e. an explosion (yep). That creates a sudden pressure that pushes out gases through every seam and hole there is.

The way to avoid this is to dial down the air in steps over a longer time, rather than burning high, and then choking it all at once (or too fast).
It also happens more when wood is not dry enough as it smolders rather than burns the gases.

 

[Gwilkrrs]

That was an awesome explanation to an inexperienced person
Thanks

 

[kborndale]

Are those Xmas decorations that appear to be touching your thimble? Hopefully they have been put away.

 

[Gwilkrrs]

They are and they were.
They were made from flame retardant paper and were close but not touching.
Next season they will be strung further away.