Please teach me about hopper fires & prevention

Hello - it's me again, the new girl with the new coal stove who's all freaking out over here. (Not really freaking out - I'm just not ever really "comfortable" with something - ANYTHING - unless I know ALL there is to know about it. I do understand my stove and basic stove safety - but I'd like to get into more specifics.)

I've searched this board for "hopper fire" over & over again and while I've found bits & pieces of information I'd really like to just have a good overview of this topic. So my questions are:

1. What are the causes of a hopper fire?
2. How quickly does the fire become uncontrollable / like, burn-your-house-down fire?
2. What safety precautions can I take to make sure that I do not ever have a hopper fire?
3. (stupid question, but I'm asking it anyway) How do you know you have a hopper fire?
4. What do you do if you are having a hopper fire? Do you call 9-1-1 right away?

Forgive me for being so basic - but I need to learn and you guys are the ones who have the answers so I don't know who better to ask.

I'll probably have more basic questions like this (if I can't find the answers I'm looking for in searching) so please bear with me. Thanks for all your help.

There's an extensive thread here to get you started: Hopper Fire - Alaska Channing 3 with direct vent

NEPAForum Admin wrote:There's an extensive thread here to get you started: Hopper Fire - Alaska Channing 3 with direct vent

Thanks, Admin...I did read through that entire post before I posted this topic. I guess I'm just looking for more general "physics" of stoves. What makes a hopper fire happen -- hopper door open, low coal, etc; prevention; and how to handle one. And not necessarily stove-specific details. I don't know if I'm making sense. I hope so.

Thanks.

Hello erinMarie, I'll try to answer your questions:
1. a hopper fire is caused by the fire burning back into the hopper coal outlet at the top or begining of the stoker mechanism. The only way a coal fire will burn is with air, if there is an air leak at the top of the coal bed, then a fire will burn up at the top. If the hopper is low on coal, the hopper cover leaks air, and the stove has strong draft, then air coming through the coal in the bottom of the hopper could support a hopper fire.
2. There are too many variables to answer this, but I would doubt that you would get to a 'burn your house down' hopper fire with a full hopper of coal, an therfor the fuel is limited for the hopper fire.
2a keep the lid on the hopper, keep the hopper reasonably full, don't run it empty, keep the grate clean and no air leaks around the top ot the grate.
3 you will burn the paint on the hopper, and you will smell this. the hopper will be very hot, the lid may be too hot to touch.
4. Well I won't say don't call 911, but if you stop air to a coal fire it goes out. So stop the stoker fans, stop the draft fan motor if it has one, if you don't , then prop the baro open, this will either eliminate any draft in the stove or significantly reduce it. Then let the fire calm down, shovel out the hopper assess the damage.

In general it depends on the stoker mechanism design if a stove is prone to hopper fires. If you are not just idling the fire, but keeping the hopper half full or so, and burning above an idle I don't think a hopper fire is likely.

Hope this helps
Greg L.

Well I'll add my .02

ErinMarie wrote:
1. What are the causes of a hopper fire?

Pretty much already explained by LsFarm, I'll add the thread I linked to above was the first time I've seen this mentioned. I've been delivering coal for 15 years so I found it odd. It's certainly possible that it happened to some of my customers. I'm going to go out on limb here and say poor design, this should not be possible to happen. The gate or pusher block should be automatically set to stop at point where it blocks off all access to the hopper.

Just add, I'd pay particular attention to what Jerry from leisure Line has to say in that thread:

Hi,
I would first find out how the draft pulled into the hopper. It doesn't matter how low your hopper is with coal, your barometric damper over rides excessive draft. Now if you don't have a barometric damper, what is there to over ride the draft ? Leisure Line will not install or sell a stove, power vent or chimney without the use of a barometric damper. This isn't the first thread in here about hopper fires without the use of a baro.
Jerry

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2. How quickly does the fire become uncontrollable / like, burn-your-house-down fire?

Subjective really, if you have it in well fire proofed setting it would most likely not catch anything on fire. The only real concern you would/should have is the ceiling . Most of the heat is going to disipate before it reaches the ceiling, I'm not saying it isn't possible but I'd suggest its highly unlikely.

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4. What do you do if you are having a hopper fire? Do you call 9-1-1 right away?

Again it's subjective , and answering questions like these is difficult because you don't want to say one thing when the situation may have multiple answers. What i would suggest if you're concerned about it is keep a bucket of sand or some other non-combustible nearby. This will smother the fire and is probably the safest and least destructive way to put it out. Note that once lit coal is very hard to put out regardless of some of the people that have issues keeping it going. Water is going to make a mess and may actually exacerbate the situation .

Crude diagram, but should help.

The room air can be pulled down thru the coal if you have any air leaks or too much draft, that is why the Baro Damper is So important and the stove's mfr. settings of around .02-04 draft. If you have too much draft, it will pull air from the hopper thru the coal, especially using a larger style coal (Buckwheat or bigger) even though MOST Mfr's do not recommend anything but RICE, it packs tight and prevents the airflow down thru the hopper, causing the flames to burn back towards the stoker/hopper. Also, if you have a hopper lid, keep it on it.

Also, sealing the burn grate and making sure you don't have any combustion air leaks towards the back of the stoker to make it burn towards the back.

Cleaning & Sealing Burn Grate

NEPAForum Admin wrote:Well I'll add my .02

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4. What do you do if you are having a hopper fire? Do you call 9-1-1 right away?

Again it's subjective , and answering questions like these is difficult because you don't want to say one thing when the situation may have multiple answers. What i would suggest if you're concerned about it is keep a bucket of sand or some other non-combustible nearby. This will smother the fire and is probably the safest and least destructive way to put it out. Note that once lit coal is very hard to put out regardless of some of the people that have issues keeping it going. Water is going to make a mess and may actually exacerbate the situation .

I'll add my .02 as well:

I just picked up a 50 lb. bag of Sodium Bicarbonate to keep on hand in the event of a coal or wood stove fire. A dry chem. fire extinguisher (which I have several) will make quite a hard to clean up mess.

If there is any suspicion that a fire may spread from the stove, call 911 first, then address the fire issue. The fire dept. would rather visit your house and not have to do anything then visit your house and put out the fire because someone waited to call them.

In my case, I was running buckwheat coal, and I'm pretty sure I had excess draft on top of that. I had my draft set for rice, and with the buckwheat, I adjusted my combustion blower without adjusting my direct vent speed. These two blowers work together to set the overfire draft.

With rice, I'd been running for weeks with zero (repeat - ZERO) indication of burnback issues, and my stove idles a lot as it's not real cold yet and our house is new and well insulated.

I think the biggest contribution to a hopper fire is excess draft, second would be leaks around the grate plate up toward the hopper end. Third would be running buckwheat.

Chris

I'm soaking up all this info since I will be running a girlie-man stoker soon, all my experience is with a manly-man hand fired stove.

In Chris's stove, the hopper lid has holes with wire mesh over them.. The factory for some reason provides a ventilated hopper. So with excess draft and a looser more open coal [buckwheat vs rice coal] his draft pulled air through the hopper and allowed the fire to travel back up the grate to the base of the hopper.

Personally I think this is a dangerous design... I'd replace the lid with a solid lid, it is inviting a hopper fire with either buck or a low hopper of rice. There is no need to ventilate the hopper unless it has inadequate draft and is getting condensation.

The fire will not burn where there is not combustion air provided.. If you look at the combustion air holes in the grates, they start several inches down from the top and the hopper, so the fire will not travel up into the hopper unless air is provided, flowing through the coal to support combustion.

I ran both rice and buck through several Leisure Line stokers, and had no issues. and I let the hopper go empty several times... not intentionally, and no fire in the hopper... but the hopper lid fit tight.

Greg L

ErinMarie; as a safeguard against disaster I would leave a clearance between the hopper and any combustible item like a wall, curtain, mitten rack, etc... In the even of a hopper fire the bottom of the hopper will get hot but it won't burn your house down unless something is touching it. this next statement of for entertainment purposes only: I wouldn't call 911unless you absolutely can't put out the fire yourself and there is a major emergency. If you pull the plug on the stove it will go out by itself pretty quickly and then you can replace any burnt stoker parts, if you call 911 the fire dept. will come in with axes and hoses and break windows and basically demolish your house. Like the other guys said have a fire extinguisher or bag of sand handy to douse a fire. As long as the stove is on a noncombustible floor and you have clearance on all sides it is a pretty safe unit, no more dangerous than any other type of heater. I think once you get the stove dialed in and used to using it a hopper fire will be something that just doesn't ever happen.

Thanks, everyone. I really appreciate your replies.

I get on a lot of people's nerves in real life because I ask so many questions about things (aside: sorry if I am getting on your nerves), but I really for some reason need to have a complete, thorough understanding of things before I'm comfortable with them. Obviously with a coal stove there are safety issues involved so it's good to understand it all - but even in goofy things, I like to know how they work. When I got a sewing machine I was irritated by it because I didn't understand how it was making two pieces of independent string (the bobbin and the spool) stitch fabric together. Till I read the assembly and saw a demo of the parts working I hated using my sewing machine.

Anyway - my point was, thanks for being patient with me, being a new stove owner and really unlearned in this world of coal. Hopefully someday I'll be an expert like you guys.

What type of stove do you have and is it installed with a direct vent, power vent or chimney?

ErinMarie wrote:Thanks, everyone. I really appreciate your replies.

I get on a lot of people's nerves in real life because I ask so many questions about things (aside: sorry if I am getting on your nerves), but I really for some reason need to have a complete, thorough understanding of things before I'm comfortable with them. Obviously with a coal stove there are safety issues involved so it's good to understand it all - but even in goofy things, I like to know how they work. When I got a sewing machine I was irritated by it because I didn't understand how it was making two pieces of independent string (the bobbin and the spool) stitch fabric together. Till I read the assembly and saw a demo of the parts working I hated using my sewing machine.

Anyway - my point was, thanks for being patient with me, being a new stove owner and really unlearned in this world of coal. Hopefully someday I'll be an expert like you guys.

The forum is here to ask questions and get information . No need to feel like you "getting on peoples nerves " .You have valid concernes feel free to ask away . I had an alaska stoker for yrs in the past never had a problem . Like the info you recieved follow the MFGs instructions and you will be fine . Start experimenting and you have more risk ,just like with anything .

I am the same way, I have to know how something works before I am comfortable with it. I second flyer's remarks.

Regarding calling the fire dept.: It's true that the fire dept. can cause a lot of damage to your home fighting a fire, that's because they have to get to the fire to put it out. However, fire departments today have thermal imaging cameras, they don't have to do the same amount of "exploration" that they used to. Please note that I said to call 911 if there is any suspicion that the fire may spread. If it's coal in the hopper, you can most likely deal with it. If anything nearby were to ignite or start to smoke, then it's time to call.

I live in a rural town, and to tell you the truth-it's my opinion that the fire dept. here is good at saving foundations.
That is my opinion. I know this from first hand experience. When I burned a wood stove into the flue I now use for coal-over time-I had 3 chimney fires, 2 minor, and the third was bad enough that I had to call the fire dept. If I had enough baking soda (which I have now) I would have climbed up the roof and put it out in about 1/4 of the time that it took them to do it. I also have several more qualified firefighter friends.

They did want to chop into the wall around the chimney to look for hot spots, but my wife told them no, to use the thermal imaging camera (that they left laying on the lawn and I almost tripped over). When they were leaving I found a Scott Pack (oxygen tank) on the second floor, which I took to them.

Don't get me wrong I have great respect for firefighters, I'm just relaying the story as it happened, form your own opinion.

They were great at pumping out the cellar, though, and they are nice guys.