And more to the point, what sort of malfunction causes a fire outside of the enclosure?

In my previous house (15-20 years ago), I had a pellet stove. I absolutely loved it. The house wasn't insulated really well, and the windows just plain sucked. But on a cold winter day I could come in after work and light that stove, and in an hour I'd have the house temperature up ten degrees. If I remember right, it was rated at 85% efficient. After a week's worth of burning, I'd have enough ash to cover the bottom of a paper grocery bag. Pellets were relatively cheap ($150/ton, I think), and a ton would last almost two months. I loved it.

This past weekend, that house burned. The fire is being attributed to a "pellet stove malfunction." So now I'm wondering, what really happened? The first thing that comes to mind, naturally, is that perhaps the outlet vent (this one was a direct-vent, right out the kitchen wall) had not been cleaned. But that's purely a guess on my part.

If I think of "malfunction," I think about the circuit board that controls the auger and fans. Maybe one of the fans (one for intake air, and one for the blower) failed? Or the board failed, causing a fan to stop? But if it's not bringing intake air in, the flame just goes out (eventually), having too many pellets and not enough air, right? If the blower fails, then there's lots of good warm air there, but it's not being pushed out into the living space. I'm not sure I see how that would cause an external fire, though.

It's a horrible thing for the family, though four of the five of them were away at the time. The one remaining at the house -- a college senior -- saw intense flame at the stove and escaped the house. Two dogs and a couple of cats apparently didn't make it. There's a fundraiser set up for them, already at over 10x its goal. (Proof that there are good, generous people in the world and in the neighborhood. I recognize some of the donors' names.)


I'm no fire detective so all I've got is guesses, but I'm wondering a lot about this and what the SF collective mind knows.

Possibly the glass in the door broke for some reason. exposing the fire box to the living space. Unlikely but possible i suppose.

An electrical fire of some sort is possible.

We have used pellet stoves continuously for 25 years. And like them quite a bit.

Going to pay attention to this thread as I use a pellet heater in my shop and have for 15 years....I tend to “forget” to take time to clean out my “through the wall” exhaust pipe every year before start up...I will make sure I clean this pipe this year before my planned start up....I only burn about 500-700lbs of pellets a year based on our weather patterns....

We had a pellet stove in our last house in Montana for about 10 years. Pellets were under $100 a ton. We loved it and never had problem one with it. It was a Whitfield. I can’t imagine how a fire would escape the stove.

I have heard of pellet stoves catching the hopper full of pellets on fire.
The usual fire pathway to the hopper is up the auger feed tube.
Try a google search for pellet stove hopper fire.
What I read matched what I heard many years ago.

quote:

Originally posted by cee_Kamp:
The usual fire pathway to the hopper is up the auger feed tube.

That's an interesting thought -- I hadn't thought about fire traveling up the auger.

Fire in the stovepipe itself maybe?

quote:

Originally posted by PASig:
Fire in the stovepipe itself maybe?

Perhaps? But I'm still curious the root cause. Is that a "lack of cleaning" thing (how much crud builds up in a direct-vent pipe)?

ORC, you're a long-time user. How often do you have to clean the vent pipe? How much crud do you get from it when you clean it?

The metal lid on our pellet stove hopper would snuff any fire attempting to start there. It would also tend to smoke up the house, indicating a problem.

An electrical issue would cause it to shut off. Feed would stop, fire would go out.

We do a pretty thorough cleaning of the stove and pipe about every ton of pellets. We burn about 3 ton every season.

quality/newer stoves have vac & thermal switches to help avoid fire from internal sources.
Well run - the only vent pipe issue should be ash.

What can happen is wood pellet fines accumulate back in the internals - unless cleaned annually-----we can what-if a long time here.

My 1st stove was a Glo-King-top auger feed--ran it for 25 years until parts were harder to come by. Top augers are very unlikely to burn back thru the auger. Now running on a Harman insert---bottom auger. The 1st ones did have a problem with auger burn back---years ago. Like any fueled device - maintenance is required.