# Wood stove "exploded"



## Saddlehillfarm (Jan 4, 2019)

Has this happened to anyone?    I have an older stove.  Every morning I clean out the ashes, which fall through slots in the floor into an ash tray.   Most of the time there are hot coals still left from the night before, and these are what I use to start the day's fire.   I take old bark and leaves and sprinkle on the coals.  Then I get some kindling wood and put on the bark and leaves,.. then i throw in a couple of logs. Then, I shut the doors in front.  (it also has a top loading door)  I pull out the ash tray a little which forms a wonderful draft that gets the fire ignited quickly.  Well this morning while I was waiting for it to ignite,,. boy did it ever.  It exploded,.. and the force was great enough that it popped open the top loading door , and also blew out underneath in the ash tray,.. covering me with smoke and bits of ash and soot from the stove.  It scared the daylights out of me.. It happened so fast.  Now I am really wary of my stove, which I have loved up to this morning.  Anyone can tell me what this was?  I know what huffing is,... this wasn't it.  I have been doing this with the same wood stove for 10 years and this is the first time I had this happen.   I do not want a repeat of this.  thank you!


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## bholler (Jan 4, 2019)

It happens smoke builds up in the firebox then ignites causing an explosion.  Vermont castings are pretty prone to this problem.  And if you have been using your ash drawer to start fires for ten years you are very lucky you havnt damaged your stove.  Most people cause cracking by doing that pretty quickly.


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## sprawlnstall (Jan 4, 2019)

Neat story.  Anyone have the scientific description of how smoke explodes?  I believe you, I just don't understand how it happened.


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## bholler (Jan 4, 2019)

sprawlnstall said:


> Neat story.  Anyone have the scientific description of how smoke explodes?  I believe you, I just don't understand how it happened.


Smoke is full of combustibles that is why you can have secondary combustion.  When it builds up in a confined space and then reaches its ignition temp it will expand rapidly causing an explosion.  It happens more often with wet wood of poor draft.  I have seen stoves cracked by this


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## begreen (Jan 4, 2019)

This exact scenario happened to me once with a Jotul and that was enough for me to change burning habits. In my case it was some damp maple wood. The kindling started normally and the maple started to burn with the door slightly ajar. I got impatient and closed the door with the air damper all the way open. Came back a couple minutes later and the flame had gone out, stove full of smoke. I foolishly cracked the ash pan door open and as soon as a flame appeared - Kawhumfph! The smoke (which is unburnt wood gases) ignited and smoke blew out of every orifice and pipe joint. That was many years back. Hasn't happened since, but it sure makes one appreciate those 3 screws per pipe joint and a proper install.

Leave the side door open a little and don't close it until you are sure the fire has a decent start. This is easier to determine on a stove with a window, but maybe you don't have that? Regardless, don't let wood smolder.


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## ShawnLiNY (Jan 4, 2019)

sprawlnstall said:


> Neat story.  Anyone have the scientific description of how smoke explodes?  I believe you, I just don't understand how it happened.



More common in coal burning appliances as under fire air causes fuel in the fire box to smolder in a low oxygen environment resulting in gasification . This is the same principle that allows combustion engines to run on wood


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## bholler (Jan 4, 2019)

I had it happen to me with a coal furnace.  Different smoke but same principle.  I had a lazy fire going that wasnt taking off as it should so i open the door and stirred the burn pot.  It ignited the coal gas in the firebox and blew out a big fireball giving me 2nd and 3rd degree burns on half my face.


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## ShawnLiNY (Jan 4, 2019)

bholler said:


> I had it happen to me with a coal furnace.  Different smoke but same principle.  I had a lazy fire going that wasnt taking off as it should so i open the door and stirred the burn pot.  It ignited the coal gas in the firebox and blew out a big fireball giving me 2nd and 3rd degree burns on half my face.


Scary stuff as Bgreen pointed out this is why you need 3 screws per joint on single wall stove pipe , I’ve definitely created a puffback or 2 loading my coal stove too rapidly always suggested to leave a lil exposed flame and this will burn off most volatiles


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## tadmaz (Jan 4, 2019)

I don't want to sound overly critical, but you put leaves in your stove?  Are the leaves still attached to branches or something?


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## bholler (Jan 4, 2019)

tadmaz said:


> I don't want to sound overly critical, but you put leaves in your stove?  Are the leaves still attached to branches or something?


Nothing wrong with using leave to start a fire


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## Nick Mystic (Jan 4, 2019)

This is an example of the same principle that can cause a farm silo to explode from a dust accumulation from loading corn or some other grain crop. A huge dust cloud forms inside the silo and then a spark occurs from something (someone lighting a cigarette for example) and all the dust ignites at once from the massive surface area lighting off all at once.


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## Pertzbro (Jan 4, 2019)

Isnt this what a blackdraft is in firefighting?


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## fire_man (Jan 4, 2019)

A backpuff once blew the WS Progress lid open. The lid is a heavy cast iron plate covered with thick soapstone. Sparks flew everywhere.

The worst part is the dog was forever scared of the stove.

Sorry to hear bholler got hurt that way.


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## Zack R (Jan 4, 2019)

A few weeks ago I burned some dry but super pitchy pine (it was <20% moisture, but was heavy like wet wood). Think of fatwood but in large split form. It didn't blow up per se, but it did start to run away when the air control was fully open, making a boom boom boom noise, flames and pressure flashing with each boom. I quickly throttled down the air and it burnt just fine but was interesting nevertheless.

Perhaps you had something similar, a really pitchy piece of wood that once it was hot enough blew apart.


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## ratsrepus (Jan 4, 2019)

My Jotul Oslo was famous for that.


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## weatherguy (Jan 4, 2019)

Saddlehillfarm said:


> Has this happened to anyone?    I have an older stove.  Every morning I clean out the ashes, which fall through slots in the floor into an ash tray.   Most of the time there are hot coals still left from the night before, and these are what I use to start the day's fire.   I take old bark and leaves and sprinkle on the coals.  Then I get some kindling wood and put on the bark and leaves,.. then i throw in a couple of logs. Then, I shut the doors in front.  (it also has a top loading door)  I pull out the ash tray a little which forms a wonderful draft that gets the fire ignited quickly.  Well this morning while I was waiting for it to ignite,,. boy did it ever.  It exploded,.. and the force was great enough that it popped open the top loading door , and also blew out underneath in the ash tray,.. covering me with smoke and bits of ash and soot from the stove.  It scared the daylights out of me.. It happened so fast.  Now I am really wary of my stove, which I have loved up to this morning.  Anyone can tell me what this was?  I know what huffing is,... this wasn't it.  I have been doing this with the same wood stove for 10 years and this is the first time I had this happen.   I do not want a repeat of this.  thank you!


Pics??


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## Woody Stover (Jan 4, 2019)

begreen said:


> Came back a couple minutes later and the flame had gone out, stove full of smoke. I foolishly cracked the ash pan door open and as soon as a flame appeared - Kawhumfph!


Right, volatile gasses build up in the box, then when you supply oxygen, it explodes.
Same happened to my wife when she first had a stove installed by a hack. He put a steel plate over the fireplace opening, then rear-vented the stove through the plate into the fireplace with a short section of connector pipe. Smoke built up in the fireplace and smoke chamber above it. She opened the door and the explosion blew the door out of her hand, and she ended up on her butt!  Then she talked to her cousin who had formerly been a sweep, and she told her she needed pipe to the top. She neglected to specify "_chimney_ pipe" so I just used snap-together connector pipe. Burning wet Red Oak, we had several chimney fires. The connector pipe would be rusted through after a few years, and when I would pull it out and throw it off the roof, it would collapse flat when it hit the ground.  I finally went to stainless snap-together pipe, which helped contain the creo juice running down inside the pipe. Finally I started reading on hearth.com and got up to speed. I'm lucky I didn't burn down the house! 


bholler said:


> It ignited the coal gas in the firebox and blew out a big fireball


Oh, my!


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## Corey (Jan 4, 2019)

I've had a couple of small back puffs over the years and one pretty good WHOOF! a few years ago that shot smoke and a big cloud of ash out.   

But overall, wood 'smoke' is definitely combustible - that is what secondary combustion does.  Wood 'gas' (coming off the wood due to heat, but no fire to actually cause a 'burn') are even more flammable.  A few have even run spark ignition internal combustion engines on that - so you're likely in the range of flammability of methane, propane, etc.

https://www.youtube.com/results?search_query=wood+gassifier+truck


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## Sawset (Jan 5, 2019)

Corey said:


> . A few have even run spark ignition internal combustion engines on that


By the end of ww2, there were over 750,000 wood gasification vehicles worldwide,  cars, trucks, tractors, tanks.


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## Sawset (Jan 5, 2019)

Saddlehillfarm said:


> I take old bark and leaves and sprinkle on the coals. Then I get some kindling wood and put on the bark and leaves,.. then i throw in a couple of logs. Then, I shut the doors in front. (it also has a top loading door) I pull out the ash tray a little



No need to be afraid of the stove - just refrain from that type scenario again. Fresh fuel, on hot coals, shutting the door effectively snuffing any flames, then introducing a significant draft means a lot of unburned gasses ready to go off, which they did. Don't let the unburned fuel accumulate. Keep a small flame going, or in your case, keep the door open to give it oxygen. Keep your face away from an opening door, and open and close doors slowly to let things equalize inside. Before any if that, open the dampers to give some air. I did something similar as you did once, only with a hotter stove. When the unburned gasses reached the top of the hot chimney, the oxygen there created a flame front that rattled the pipes all the way back to the firebox, where it woofed so hard I was lucky it didn't blow the glass out.


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## Rearscreen (Jan 5, 2019)

Reminds me of my older brother doing this when we were kids.


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## Knots (Jan 5, 2019)

I'll have to revisit the manual for my stove, but I don't recall a warning for this scenario in it.  Do most stove manuals wan against this?


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## Matt93eg (Jan 5, 2019)

I had one on my last stove. Wasn’t huge but enough to get my attention and take an evaluation on what I needed to change so that it didn’t happen again.


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## Saddlehillfarm (Jan 5, 2019)

tadmaz said:


> I don't want to sound overly critical, but you put leaves in your stove?  Are the leaves still attached to branches or something?


We stack the logs on our porch,. and every once in awhile I sweep up the excess bark and leaves that are mixed in together to use for starting the fire.


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## Saddlehillfarm (Jan 5, 2019)

Thank you everyone for your very informative input !. You are all fabulous.   My husband I were ready to go buy a new stove yesterday,.. but your experiences you wrote about  showed us that this can happen with any stove.  From now on,.. I will make sure that the front doors are open to get plenty of oxygen , and that the fire has ignited before I shut them.  It is strange though that this has never happened before for many years? Thank you again


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## Saddlehillfarm (Jan 5, 2019)

weatherguy said:


> Pics??


It is a stove with 2 window doors that open outward, and then a top loading door.  There was a comment on maybe it was a certain type of wood, or dampness,... no,.. no pitch or wet wood. Same ole wood we have been using for years,.. my husband goes out and cuts down the trees, our next door neighbor has 60 acres worth..


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## Saddlehillfarm (Jan 5, 2019)

Knots said:


> I'll have to revisit the manual for my stove, but I don't recall a warning for this scenario in it.  Do most stove manuals wan against this?


You know I thought the same thing.. I had never read or heard of this before.  this is something that should buyers should be aware of?


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## ShawnLiNY (Jan 5, 2019)

I’m not sure if wood stove manufacturers warn against this because loading the stove while hot usually just ignites whatever fuel is placed on the hot coals ( for a puffback to occur ) you need a series of unlikely circumstances to align , really hot stove with no exposed coals or flame , load of unlit fresh fuel , low enough air intake to allow volatiles to build to combustible levels


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## begreen (Jan 5, 2019)

Sometimes it just takes the right combination of ingredients for a mishap to occur. Having a proper installation and proper operation make them a rarity. The only mistake made here was the the door wasn't left slightly open to provide oxygen to the fire. You can close it once the fire has started to burn in earnest.

(PS: This doesn't need a hot stove to happen. Our incident was on a cold start.)


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## ShawnLiNY (Jan 5, 2019)

begreen said:


> Sometimes it just takes the right combination of ingredients for a mishap to occur. Having a proper installation and proper operation make them a rarity. The only mistake made here was the the door wasn't left slightly open to provide oxygen to the fire. You can close it once the fire has started to burn in earnest.
> 
> (PS: This doesn't need a hot stove to happen. Our incident was on a cold start.)


Much more likely to happen in a hot stove .how is your stove gasifying fuel without sufficient heat?


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## firefighterjake (Jan 5, 2019)

Pertzbro said:


> Isnt this what a blackdraft is in firefighting?




Pretty similar . . . fire is starved for oxygen and generating combustibles in the smoke. Oxygen source is introduced and "Kah-wummpfff."


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## weatherguy (Jan 5, 2019)

Saddlehillfarm said:


> It is a stove with 2 window doors that open outward, and then a top loading door.  There was a comment on maybe it was a certain type of wood, or dampness,... no,.. no pitch or wet wood. Same ole wood we have been using for years,.. my husband goes out and cuts down the trees, our next door neighbor has 60 acres worth..


I was just kidding around, wanted pics of the explosion


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## bholler (Jan 5, 2019)

ShawnLiNY said:


> Much more likely to happen in a hot stove .how is your stove gasifying fuel without sufficient heat?


Most cases I have heard were from cold starts


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## ShawnLiNY (Jan 5, 2019)

bholler said:


> Most cases I have heard were from cold starts


Again a cold start is starting a fire not reloading and reviving an existing one , how are gases accumulating in you’re scenario if there aren’t coals and burning embers and residual heat ?


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## bholler (Jan 5, 2019)

ShawnLiNY said:


> Again a cold start is starting a fire not reloading and reviving an existing one , how are gases accumulating in you’re scenario if there aren’t coals and burning embers and residual heat ?


Smoke accumulates because the wood is just smouldering.


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## jetsam (Jan 5, 2019)

Sawset said:


> By the end of ww2, there were over 750,000 wood gasification vehicles worldwide,  cars, trucks, tractors, tanks.



They were around in WWI, and hobbyists are still making them today.

I expect you could even have the gasifier separate from the vehicle and run it like a propane vehicle with some extra filtration.  Haven't seen anyone doing that, though.


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## begreen (Jan 5, 2019)

ShawnLiNY said:


> Much more likely to happen in a hot stove .how is your stove gasifying fuel without sufficient heat?


It happened pretty easily as I described earlier with good dry kindling but not so dry wood. You get 4-5 splits starting to burn and then cut off the air and the stove will get filled up with smoke.. The wood was trying to burn and if I had left the door open a little it would have instead of smoldering.


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## ryanwc (Jan 5, 2019)

Pertzbro said:


> Isnt this what a blackdraft is in firefighting?



It's worth mentioning that the video has a surprise ending.  I couldn't understand the guy's accent, said to my wife, well, I don't know if it's worth watching to the end, and almost missed the payoff.


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## Saddlehillfarm (Jan 7, 2019)

ShawnLiNY said:


> Much more likely to happen in a hot stove .how is your stove gasifying fuel without sufficient heat?


my explosion happened with a cold stove.  Just a few coals in the ashes


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## Saddlehillfarm (Jan 7, 2019)

bholler said:


> Most cases I have heard were from cold starts


yes, mine was a cold start


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## Corey (Jan 13, 2019)

Must have forgot to 'knock on wood' when I posted... just last night the stove burned down to coals and I put a small pile of bark, sticks and junk from around the splitter in.  I was in the adjoining room a few minutes later and heard "WHOOMMMMFFFF!"  I do this same process practically daily and 99.9% of the time, no issues, but when all the elements come together... Wow!

The video above is pretty amazing.  On the stove side, we tend to define 'backdraft' as cold air coming down the flue.  On the firefighting side, not sure if they would look at the big puff and say 'that' was a backdraft, of if they tend to define backdraft as fresh air flowing back into a smoke filled room, resulting in a flashover - which would be the big puff.

Either way, when I have encountered the situation, it's been slightly different as the stove has just 'misbehaved' all on its own.  Smoke and wood vapor filled the firebox, the coals finally got hot enough and WHOOF!  I didn't specifically open a door or open the draft to let more air in.  Though I can imagine that rare instance when someone would say "What the heck is all that smoke in there... let me open the door and poke things around a bit" ...and that tiny bit of extra air from the door would be the trigger.


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## begreen (Jan 13, 2019)

Looks great. That is one of the most handsome inserts on the market and a good performer too.


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