Hopper Fire last night

[Eyball]

last night we came home to a smoke filled house and ends up the pellets in the hopper had ignited. We have a Breckwell P4000 Vermonter that I purchased used last winter and installed in March. We have run about a ton without any issues. I think last night was the coldest temps we have run it in though. My setup is in the finished basement with outside air connected. I have 3" pipe coming off the stove starting with a T then up 4 feet to a 90 degree elbow and then through a wall thimble about 18" into a masonry chimney where I have an increaser T going to 4" and the 18' of pellet vent pipe up and out the top of the masonry chimney. The top being few feet of the masonry chimney insulted and sealed off. When I ran a wood stove I often had negative draft issues but that was just 6" pipe off the stove and into the wall thimble the dumped into the clay lined chimney.

The hopper fire was easily extinguished with a fire extinguisher and house aired out. If we were home it probably would have been much better. I'm thinking it was smoldering for a while. The stove has no seal for the hopper just a cheap lid. I'm thinking it was so cold and calm last night tha cold air was dropping down the pipe and the stove was smothering itself which caused it to start venting out the hopper. The combustion fan still comes on and besides creosote buildup in the hopper & fire box there is no other damage. The fire was smothering itself out but had enough air from the oak & non sealing hopper lid to allow the pellets to smoldering until I hit it with the extinguisher.

So I guess at this point I am looking for some advice. I hate to buy a new stove but maybe that's the best option....

Thanks & Happy New Year!

 

[SmokeyTheBear]

That installation calls for 4" vent and venting should not change partway through the vent run and it should be that way all the way to the cap.

Could you explain exactly what you did after you got the stove and before you fired it for the first time.

 

[John Fortier]

Thank God all are ok and your home is still intact.

 

[MuchoBueno]

Yes very scarry. Good you were able to get it under control.

 

[Eyball]

The stove was purchased by a friend of mine in 2008 & never installed. It had never been burned when I got it. I just installed it where my wood stove was but I ran the pellet vent from the stove, through the 6" wall thimble & up the chimney. It's pellet vent all the way. I know the manual called for 4" all the way but I had 3" pipe that came with the stove I didn't want to waste. Do you think this could be to blame? I certainly don't want to go through last night ever again. I can easily buy some 4" pipe. Would I use the increaser T off the back of the stove? It's only a 3" output on the stove.

Thanks for the help!

 

[SmokeyTheBear]

A lot more will need to be known about your installation however most vent and chimney systems that have a choke point in them have problems with establishing proper air flow even without having other things in the mix.

Was this stove operating on a t-stat in any fashion and if so in which mode was it operating?

Was the stove installation gone over by an inspector?

Was there any air handling device that could automatically cycle on?

Did you ever have the pressure situation in your basement checked? Basements are subject to chimney effect (this increases each floor down you go) regardless of if there is a chimney in the house.

 

[boo boo]

Glad you, your family and your home is okay. Could have been a very bad start to the new year. I suggest you don't run that stove until you find root cause and fix it. But I am sure you know this.

 

[Polar Bear]

Is that a bottom feed?

 

[SKOAL MAN]

I thought hopper fires were an urban legend, but this is the second this month! Glad to hear that you're alright! I thought about doing through the wall vent when I installed my stove but I had a tall chimney and the added benefit of the natural draft sold me. Depending on how tall your chimney is its a lot harder to push smoke up a 3" than 4".

 

[Eyball]

The stove was not on a t-stat it has 4 heat settings. It was on 2 then I topped off the hopper & set it to 3 before we went out. The only other thing in my basement that would have cycled on is my oil burner & it's forced hot water on a separate chimney. When I installed my wood stove it was inspected but not when I switched over to the pellet stove. Mainly because the builder inspector did nothing when he signed off on my wood stove. I know I should have. The basement has not been tested but I can tell you with the stove disconnected cool air is coming out of the chimney pipe. I don't plan to re-fire thus thing without figuring out the problem & having it inspected. Maybe an entire new stove.

 

[Eyball]

Oh, it's a top feeding gravity drop auger. Thanks

 

[SmokeyTheBear]

If you get a chance would you please take some pictures of the chimney on the outside?

I want to get some feel for relative heights of the chimney and roof ridges.

Just so you understand things that DHW system can create a negative pressure situation in your entire basement depending on how well things are sealed between the stove room and the boiler room.

Were there pellets backed up into the drop chute and/or in the burn pot?

 

[Eyball]

The stove & boiler are in separate areas of the basement but by no means well sealed off. The basement itself is pretty air tight. I used to have to open a window many times starting my woodstove to prevent smoking out the basement. The burn pot was basically empty but the auger was full of partially burnt pellets when I open it up & cleaned it today. The chute was clear but lots of creosote buildup right below and on burn pot. I will post a picture of the chimney tomorrow. Oh, it also runs up through my garage so the chimney is all in un-heated space.

Just notice your in Standish. I have been going to Frye Island for 30 years! Thanks again for assistance!

 

[Polar Bear]

I'm confused how it started.... I assumed the drop chute would've been backed up?

 

[Eyball]

My best guess is the chimney down draft due to extreme cold last night was over powering the combustion blower & due to crappy design on my hopper the fire started venting up the chute & ignited the pellets in the hopper auger & worked down to the bottom of the hopper. I'm actually surprised the stove components are still ok. I believe the auger had shut off but the damage was done at that point & luckily the hopper just smoldered & did not really have a good air source. I was thinking the combustion fan crapped out but it still works... I'm no expert by any means though, that's why I'm checking here for help. Thanks

 

[rona]

My best guess is the chimney down draft due to extreme cold last night was over powering the combustion blower & due to crappy design on my hopper the fire started venting up the chute & ignited the pellets in the hopper auger & worked down to the bottom of the hopper. I'm actually surprised the stove components are still ok. I believe the auger had shut off but the damage was done at that point & luckily the hopper just smoldered & did not really have a good air source. I was thinking the combustion fan crapped out but it still works... I'm no expert by any means though, that's why I'm checking here for help. Thanks

Do you have fresh air hooked up to this unit? Earlier in the description you mentioned you needed to open a window for more air when you started a wood stove fire. I am thinking a fresh air intake may be the corrective procedure.

 

[alternativeheat]

If you have a lot of creosote built up in the auger system then burn back, or the negative draft situation at least ,doesn't sound like a single event to me. Just this time it made it to the hopper.

FWIW, I ran venting through a masonry chimney as well on my Harman which has a 3" outlet . I adapted to 4" right at the stove and ran 4" all the way through. I have a strong positive draft up the venting. And additionally if your chimney top is below the peak, in which case you need clearances to the pitch of the roof and or clear the peak. If not adhered to you can get bad downdrafts, temporary or constant according to wind direction over the peak. It should all be in your manual.

 

[Phoenix Hatchling]

OP stated he had an OAK installed.

 

[alternativeheat]

OP stated he had an OAK installed.

Hmmm, I missed that. Well one down. I'll edit that out, thanks.

 

[Phoenix Hatchling]

If you have a lot of creosote built up in the auger system then burn back, or the negative draft situation at least ,doesn't sound like a single event to me. Just this time it made it to the hopper.

FWIW, I ran venting through a masonry chimney as well on my Harman which has a 3" outlet . I adapted to 4" right at the stove and ran 4" all the way through. I have a strong positive draft up the venting. And additionally, I think one place where Smokey is headed is that your chimney top is below the peak, in which case you need clearances to the pitch of the roof and or clear the peak. If not adhered to you can get bad downdrafts, temporary or constant according to wind direction over the peak. It should all be in your manual.

So our Harmans with the steel drop door would prevent this? Seems I read of a Harman having an issue as well one time, and that the design of the hopper lid/gasket snuffed it out by sealing itself off. I may be mistaken on the brand that was but I thought that was Harman and thinking, "cool, I guess I'm covered".

 

[alternativeheat]

So our Harmans with the steel drop door would prevent this? Seems I read of a Harman having an issue as well one time, and that the design of the hopper lid/gasket snuffed it out by sealing itself off. I may be mistaken on the brand that was but I thought that was Harman and thinking, "cool, I guess I'm covered".

It's a good theory though they can stick. It's advisable to make sure that the drop gate is working free. There have been accounts where after some years use they get sticky. A couple of members here have a plan where they pull the auger system for cleaning on a 4 year schedule for instance. But you can check the gate anytime in between. I've flipped the gate on my P61 during a fines box clean so I know it's free. I found it a bit concerning that on shutdown pellets burn back a ways into the auger tube but others here claim the same thing with their Harmans.

 

[SmokeyTheBear]

Once again it needs repeating any pellet stove can suffer from burn back.

Smokey is at the moment not headed anywhere I'm trying to gather as much information as possible.

It normally takes several things to get from running fine to the point of having a situation such as that which is posted here.

The issue that alternativeheat is talking about is known as the gummy stove syndrome. A relative vacuum in the sealed hopper (caused by air and pellet depletion) draws some exhaust into the hopper where it condenses causing creosote build up a bad thing anytime. There is a fix for this.

The same thing can happen if the room a stove is in a can place the hopper under a relative vacuum and the hopper is not sealed.

 

[SmokeyTheBear]

I'm confused how it started.... I assumed the drop chute would've been backed up?

It is possible for the hot exhaust gases to start a fire or roast things anywhere they can get to within a certain distance from the fire..

One of the normal (and likely the most common one) burn back situations is exactly as you describe but it isn't the only possible one.

The pileup case is usually signaling it is about to happen well before it does.

I also want Eyball to know that it is nice to have somebody that has had this situation occur to actually stick around and provide additional information.

 

[Eyball]

I do have outdoor air hooked up. I figured in the basement I really needed it. If I open the stove door without the stove running I can feel the cold air coming in through the stove. I have been doing a good job of cleaning this stove & there has been less than a ton burned since install. The creosote was only notice after the hopper fire, I think it's all from that event. I do want to point out the glass had been getting dirty pretty quick but the flame seamed good. I will take some pictures later today and post.

 

[Eyball]