# Can the pellets in the hopper catch fire???



## md2002 (Jan 6, 2015)

This is probably a stupid question but we have some very cold temps coming in the next few days (-25 degrees fahrenheit for Thursday) and tonight I turned the stove up all the way, I've never done this before. When I went to fill up the hopper after running like this for a few hours I noticed the pellets in the hopper are extremely hot! Is there any chance pellets can catch on fire in the hopper from the heat the stove is putting out underneath them?

I doubt this will happen but it's worth asking.


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## Dr.Faustus (Jan 6, 2015)

the pellets can catch fire in the hopper but probably not the way you are thinking. First off, check your seals between the hopper and the lid. the lid should seal air tight, this way, if they do catch fire, its never more than a smolder because there is no oxygen in the hopper to let them burn. second, and this depends on what stove you have, the pellets can get jammed up in the auger chute especially if the auger stops working. this will let the fire travel up the pellet path to the hopper. If you have a great seal on the lid and all the safety switches on the stove work, this shouldnt wind up being extraordinarily bad, just a bit smokey in the house. the hopper is usually made out of the same metal as the stove,

my brother had a hopper fire once in his englander due to a bad bottom auger. Mom was the only one home, she noticed the smoke and unplugged the stove (she was too afraid to do anything else to it) It then sat until my brother got home. what he found was the fire extinguished itself over time and it did leave an ashy mess with some sticky tar like crud in the hopper but he got it all clean, fixed the auger and stove still runs fine.


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## SmokeyTheBear (Jan 6, 2015)

Read here https://www.hearth.com/talk/threads/hopper-fire-last-night.138218/  and when you finish I'll find another one for you to read if you ask.

You did install your stove by the book correct?

You haven't made any modifications correct?

You have cleaned the entire stove system completely on a regular schedule correct?

You burn only fuels the stove is rated for correct?

If you answer all of the above with a yes then the chances of such a thing occurring in the manner you are thinking of is extremely remote.   

Is it zero, no, I don't think that everything that could happen gets factored into the testing or design of any heating system.


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## Bioburner (Jan 6, 2015)

SmokeyTheBear said:


> Read here https://www.hearth.com/talk/threads/hopper-fire-last-night.138218/  and when you finish I'll find another one for you to read if you ask.
> 
> 
> 
> Is it zero, no, I don't think that everything that could happen gets factored into the testing or design of any heating system.



The human element is the bad one in most cases


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## md2002 (Jan 7, 2015)

SmokeyTheBear said:


> Read here https://www.hearth.com/talk/threads/hopper-fire-last-night.138218/  and when you finish I'll find another one for you to read if you ask.
> 
> You did install your stove by the book correct?
> 
> ...



Yes to everything..... I'll read the article as well.... thanks!


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## SmokeyTheBear (Jan 7, 2015)

Ok, 

Here is one more https://www.hearth.com/talk/threads/pellet-hopper-fire.137327/


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## md2002 (Jan 7, 2015)

SmokeyTheBear said:


> Ok,
> 
> Here is one more https://www.hearth.com/talk/threads/pellet-hopper-fire.137327/



Thanks, the last one was some good reading.... As I said, I've never actually noticed the pellets being this hot but the stove was turned up pretty high and I imagine the pellets need a flame to ignite. I should also mention my stove is a Enviro Milan insert. I'm not sure how free standing stoves work but basically the pellets in my stove sit right above the flame in the hopper, and the hopper lining (under the pellets) is VERY hot, can't even touch it. If I take a handful of pellets out of the hopper they are hot to the touch from the heat being put out by the stove.... again, they probably need a flame to ignite no matter how hot they are... it was worth asking the question though.


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## Bioburner (Jan 7, 2015)

One cannot comfortably touch metal much above 120. 130 and you will burn with water. Ignition of wood is around 600


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## SmokeyTheBear (Jan 7, 2015)

I saw the stove information, no need for a flame just, fuel, air (oxygen), and a source of heat that reached the ignition point of the fuel.

Which for pellets is well above what makes it impossible for you to touch.  If you have a IR thermometer take the hopper's temperature.


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## F4jock (Jan 7, 2015)

Autoignition of wood takes place at approximately 572f but needs sufficient oxygen.


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## Deromax (Jan 7, 2015)

I tend to side with Bioburner.  Anything you can touch and not burn your skin is probably not hot enough to set wood on fire.


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## F4jock (Jan 7, 2015)

Deromax said:


> I tend to side with Bioburner.  Anything you can touch and not burn your skin is probably not hot enough to set wood on fire.


You tend correctly. If you can touch it and keep your hand on it it's 120f or below.


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## Highbeam (Jan 7, 2015)

F4jock said:


> You tend correctly. If you can touch it and keep your hand on it it's 120f or below.


 
I do a lot of metal work, I disagree with this. Submerging your hand in hot water or grease at 120 is not the same as touching a hot surface. 200 degree metal is relatively painless to hold your hand on. In the woodstove world we generally agree that a stove has gone cold and stopped making heat under 300. Get an IR gun and find a 200 degree surface to touch.


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## F4jock (Jan 7, 2015)

Highbeam said:


> I do a lot of metal work, I disagree with this. Submerging your hand in hot water or grease at 120 is not the same as touching a hot surface. 200 degree metal is relatively painless to hold your hand on. In the woodstove world we generally agree that a stove has gone cold and stopped making heat under 300. Get an IR gun and find a 200 degree surface to touch.


No thanks. Already messed with metal at 
150f by IR. It burns. You can do it for me.


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## Highbeam (Jan 7, 2015)

F4jock said:


> No thanks. Already messed with metal at
> 150f by IR. It burns. You can do it for me.


 
Sure, that's like touching a very cool flue above a nearly dead fire. So cold that even spit wouldn't steam.


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## F4jock (Jan 7, 2015)

Highbeam said:


> Sure, that's like touching a very cool flue above a nearly dead fire. So cold that even spit wouldn't steam.


Be my guest


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## SmokeyTheBear (Jan 7, 2015)

Children please play nicely now.

Thank you.


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## F4jock (Jan 7, 2015)

SmokeyTheBear said:


> Children please play nicely now.
> 
> Thank you.


Front of stove door is 154f. Can keep finger there for approx one second ×/- before it hurts. Temp is temp just like calories are calories.


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## sportbikerider78 (Jan 7, 2015)

Dr.Faustus said:


> the pellets can catch fire in the hopper but probably not the way you are thinking. First off, check your seals between the hopper and the lid. the lid should seal air tight, this way, if they do catch fire, its never more than a smolder because there is no oxygen in the hopper to let them burn. .



My drolet has no seal at all on the lid of the hopper.  It was never there.  

If it takes 500F+ to cause ignition for wood and the material is a certain type of steel..and it has to travel XX inches,,,It is a simple heat transfer calculation to figure out how hot the stove needs to get to achieve 500F inside the hopper.  You can be sure the engineers did that calculation.

It would be kinda like worrying if your fuel injection system on your car could catch on fire.  Sure, anything can happen when you have fire and combustibles, but not when it is operating properly.


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## Highbeam (Jan 8, 2015)

F4jock said:


> Front of stove door is 154f. Can keep finger there for approx one second ×/- before it hurts. Temp is temp just like calories are calories.


 


SmokeyTheBear said:


> Children please play nicely now.
> 
> Thank you.


 
I hope we all have pretty thick skin, mine just must be thicker.

Over 200 on the stove, it is hard to take a photo and hold everything. Easy to hold my hand on a 200 degree surface for at least several seconds. I am not willing to put my hand in a pot of 200 degree water. Temperature is temperature but there is so much more to determining temperature by touch.


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## SmokeyTheBear (Jan 8, 2015)

sportbikerider78 said:


> My drolet has no seal at all on the lid of the hopper.  It was never there.
> 
> If it takes 500F+ to cause ignition for wood and the material is a certain type of steel..and it has to travel XX inches,,,It is a simple heat transfer calculation to figure out how hot the stove needs to get to achieve 500F inside the hopper.  You can be sure the engineers did that calculation.
> 
> It would be kinda like worrying if your fuel injection system on your car could catch on fire.  Sure, anything can happen when you have fire and combustibles, but not when it is operating properly.




In case nobody has noticed we accumulate the abnormal operation corner cases on here.


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## F4jock (Jan 8, 2015)

Highbeam said:


> I hope we all have pretty thick skin, mine just must be thicker.
> 
> Over 200 on the stove, it is hard to take a photo and hold everything. Easy to hold my hand on a 200 degree surface for at least several seconds. I am not willing to put my hand in a pot of 200 degree water. Temperature is temperature but there is so much more to determining temperature by touch.


According to the ASTM the contact temperature that a human can stand for approximately 5 seconds after which one gets a first degree burn is 111 to 139f depending on the thermal conductivity of the heated surface. Metal is considered highly thermally conductive, ergo either  the time or temperature would have to be lower to avoid said burn. My conclusion: If you can hold your hand on metal heated to an honest 200f perhaps you should be applying for membership in the X-Men or questioning  the accuracy of your thermometer.


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## F4jock (Jan 8, 2015)

SmokeyTheBear said:


> In case nobody has noticed we accumulate the abnormal operation corner cases on here.


Yeah. And everyone knows a fuel injected Stingray can NOT beat a 413 in a quarter mile drag, Beach Boys notwithstanding.

Even with slicks. . . . . .


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## Snowy Rivers (Jan 8, 2015)

MOST PELLET STOVES have over temp snap switches that chop the power at 250 F
These are located in the area of the drop tube and the heat exchanger bonnet.

If the stove gets that hot it's going to shut off.

Fire is always a possibility with any appliance that has combustion going on inside, or any exposed elements that get hot (Red) as in electric heaters.

Oil furnaces, gas furnaces, propane heaters, electric wall heaters, pellet stoves, wood stoves, coal stoves, and on it goes.

We must be ever vigilant that our friendly fire is always seriously supervised when it's allowed to play.

Is it common to have a hopper fire, NO, CAN it happen ? YES, BUTTTTTTTTTTTTTTTT, SO CAN A VOLCANO 


Be safe.

Snowy


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## Francois (Jan 9, 2015)

md2002 said:


> again, they probably need a flame to ignite no matter how hot they are... it was worth asking the question though.




Like Smokey said, you need fuel, oxygen and a heat source.  Your stove has an igniter, no flame, just heat.


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