how do hopper fires happen??..are newer stoves safer? auto safer than manual?

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Ericwest

New Member
Dec 17, 2012
28
I am new to the pellet stove world...and about to install an older manual stove...the prospect of a hopper fire is pretty damn scary...how do they happen?...I would think there would be some protection against hopper fires built into the design??.....so is an older manual pellet stove more likely to have a hopper fire than a new automatic stove?...if so..why??....what would be some ways to limit the possibility of a hopper fire..?? .
 

SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
Failure to operate and maintain the stove properly is the most common cause of hopper fires.

If you keep the hopper closed and turn off the stove most hopper fires are self limiting and only physically damage the stove, they will however let more than a little bit of smoke into the house.

What can quickly cause a hopper fire is not keeping the stove clean and having a poor air flow through the stove. It is usually ash piling up in the burn pot that alows pellets to pile up in a feed system, once the fire burns back up the pellet train it finds the hopper.

Usually by that time it is more of a smoldering mess than a roaring fire. Now if you give that smoldering mess some access to oxygen by opening the hopper you'll have more of a problem on your hands than you'll want to deal with.

Some stoves have burn back sensors that will cut the pellet flow before it reaches the hopper, others have a sealed gasketed hopper that will smother any smoldering mess inside the hopper, that is provided you don't open the lid.

Now what are you calling a manual stove?
 

rona

Minister of Fire
Apr 2, 2008
1,015
southwestern Minn
I am new to the pellet stove world...and about to install an older manual stove...the prospect of a hopper fire is pretty damn scary...how do they happen?...I would think there would be some protection against hopper fires built into the design??.....so is an older manual pellet stove more likely to have a hopper fire than a new automatic stove?...if so..why??....what would be some ways to limit the possibility of a hopper fire..?? .
Operator error accounts for most of the problems. Read the manual and do what it says. Some folks will forget and leave the hopper door open when it should be closed.
Some stoves will have a "Kill" switch wired so if the door is left open it will shut off. Others will have different safety features . Your exh system will also play a part as will your outside air system.
What brand and model stove did you buy? Chances are someone has one like it and will give you advice pertaining to that model.
 

Crane Stoves

Burning Hunk
Apr 22, 2012
209
Duxbury, MA.
Most of this advise is written by our very own Smokey The Bear... EDIT: sorry Smokey, you posted here as i was getting some of your old posts LOL (thats how fast our smokey is)

The conditions that lead to burn back on drop feeders is not checking the burn pot for build up (burning the wrong or sub par fuel) or having a burn pot air bypass (bad gaskets, door becoming slightly ajar or not latched shut) or improperly set damper or a dirty stove will make what might be a minor air flow issue into a major airflow issue and cause buildup, Fly ash or build up in the pipe/chimney that prevent proper drafting, all which can lead to burn back.

By design some hopper so not have a gasket or latch of any kind on the lid... suggest getting one to limit air's ability to invade the hopper.

Most but not all bottom feeders (pusher stoves) will push the crud out of the burn pot.

Bottom feeders have other ways of causing a backup and hopper fire to happen.

In addition a stuck overheat sensor that doesn't open can cause hoppers to get very warm and unless other safeties intervene could get a hopper burning.

Most hopper fires are smoke generators rather than raging infernos and the stove will contain it provided you don't open the hopper and give it more air.

to read his entire advise look for his posts IE: https://www.hearth.com/talk/threads/first-pellet-stove-house-fire-for-this-season-just-a-little-burn-back.76610/
 
D

DexterDay

Guest
Smokey is a well versed man in these here Forums :)

The type of stove will determine how safe, or unsafe it may be?

What model do you have?
 

343amc

Feeling the Heat
Nov 23, 2005
375
West Michigan
All of the above describe what happened with my Eclipse (same brand the OP has).

In my case it was a combination of an inexperienced operator (me) and an unforgiving stove. My Eclipse plugged easily with ash and had a manual draft control that had a tendency to work its way closed, causing a dirty burn which caused the 'smoldering mess' as described by Smokey.

I pulled the stove and replaced it for peace of mind. I still have it and use it in my workshop but don't let it burn unattended.

That doesn't mean yours will have the same problem mine did. As I mentioned previously, I think the previous owner had modified/bypassed some things unbeknownst to me at the time. I had no idea what operating a pellet stove entailed when I bought that unit and didn't have the sense to ask questions then like you are doing now. With age comes wisdom, or so they say.
 
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SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
You should pull up Mike Holton's comments from that same thread, he has to deal with the results of pellet stove messes for England Stove Works..

Also hearthtools comments in many threads and his stickies at the top of the forum, they spell it all out as well. Sometimes with pictures.

Snowy River's post on being a pellet stove operator at https://www.hearth.com/talk/threads/owning-a-pellet-stove.61838/
 

stoveguy2esw

Minister of Fire
to my knowledge, nobody has come up with a pellet stove impervious to burnback. that said industry wide pellet stove manufacturers work very hard to make a burnback something that should only happen when a bunch of stuff has to go wrong at the same time.

biggest defense an owner has against this happening is to be diligent with their unit. ensure the installation is done properly and to manufacturers specs. practice good cleaning schedules, maintain the stove. keep an eye on gasket wear and replace if suspect.

i say it all the time to my customers. a clean well maintained stove will be there and running, you can count on it to do so. OTOH a neglected stove will eventually turn its back on you when you really need it. pellet stoves are remarkable machines, they can save you a ton of money when compared to traditional heating appliances burning fossil fuels. but this does come with a price in "sweat equity" the stresses on components doing the jobs they do in what is essentially a "baby blast furnace" environment for hours on end is hard enough, making them work harder by allowing ash buildup can shorten their operating lifespan resulting in having to spend the savings on costly repairs.

keep em clean and ship shape folks, best advice i can offer;)
 

Crane Stoves

Burning Hunk
Apr 22, 2012
209
Duxbury, MA.
I've long agreed with stoveguy's comments, which is why its hard for me to get "on-board" with pellet/stoker stoves over a quality manual feed coal stove. I had to spend so much time adjusting, cleaning, maintaining, spending, fine tuning, worrying, not sleeping, paying a premium for bagged fuel, etc. that it just never worked as good for me as a simple shake/load in the morning & simple "shake/load" at night and I never have to worry about electronics, electricity, wires, fumes, burnbacks, fans, feeders, etc. I know different strokes for different folks and all that BUT it was an easy decision for me (no offense to those who enjoy these automated machines), just letting him know their is a choice, and it is an option for him to never have to worry about these things.
 

DirtyDave

Feeling the Heat
Nov 22, 2011
289
western wa
No one has anwsered the ops question yet. I have been wanting to know this as well as I dont picture this possible without a flawed stove. So get techy and draw us some pictures with sidewalk chalk.
 

SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
The reason the OP's question hasn't been directly answered is that it isn't a failure on the part of either a manually operated or automatically operated pellet stove that causes a hopper fire, it is the operator that failed by neglecting to monitor his fire.

An inspector from a fire department would cite you for failure to maintain a proper fire.

Frequently a stove may detect a related issue and shut the stove down. Some stoves go to extra measures to help stop the issue from expanding from bad to worse. Some stoves even try to detect a burn back situation.
 
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SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
and....noone knows Zumba better than Smokey either! !!!
All of those folks that decided to come forward to the DA instead of being issued subpoenas and that being plastered in police blotters will slowly be revealed. If for no other reason than the press loves a good mess.
 
L

Lousyweather

Guest
All of those folks that decided to come forward to the DA instead of being issued subpoenas and that being plastered in police blotters will slowly be revealed. If for no other reason than the press loves a good mess.
yea, should save the names for a slow news day.....
 

SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
Well I suppose I could point you to imacman's well over a ton of pellets through his stove without issues or opening the door or hearthtool running his stove for a very long time between opening it up for cleaning or jtakeman taking a walk on the wild side or even this dummy's 26 bag run on low of all settings without opening the door.

But that would detract from the primary point of doing your job as the stove's operator, which is to both feed it and monitor it.

In general larger units are far more tolerant of ash build up (jtakeman's and hearthtools Omegas) than smaller units are (imacmans CPM-10), multi fuel units do a lot of their own burn pot cleaning (all three of the other operator's stoves), mine on the other hand isn't a large unit nor is it a multi fuel unit, even then I managed to get through 26 bags on the dirtiest burn setting on my stove, further unlike the other units and the OP and DirtyDave's units I have only a fixed pellet feed level to play with.

Units with 4" vent systems are also more tolerant than those with 3" vents. The trick is in the air/fuel ratio and being able to maintain that ratio throughout the burn, this produces the best burn with the least ash and allows the stove to burn many bags between ash buildup in the burn pot requiring a cleaning or causing burn back.

Personally I'd like to get my paws an a WIseway to find out how well that puppy reacts to long burns without cleanings.

I also have experience with coal fired heating systems, I don't mind the shake and load setup at all Mr. Crane, it is the clean up that I object to in my old age.

Abner and a few other old timers would be having a good laugh reading a lot of threads here on hearth.com and they never blew up a single coal fired high pressure steam boiler. Unfortunately time has claimed them all.
 

SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
I didn't realize that Standish, ME was in Maine, I always thought it was in Florida, plenty warm here so it must be in Florida and that snow failing outside is fake.
 

moey

Minister of Fire
Jul 12, 2012
1,455
Southern Maine

SmokeyTheBear

Minister of Fire
Nov 10, 2008
13,363
Standish, ME
One of the easiest ways of lessening the chances of hopper fires is to properly vent your stove, keep the venting and interior stove air passages clean, use outside air, maintain all of the gaskets and closures on your stove, properly adjust your fuel/air ratio to provide a proper fire, burn the lowest and lightest ash producing pellet you can afford, monitor the buildup in the burn pot and react to that build up by shutting down and cleaning things out.

In other words, follow the operating instructions in the fine manuals ;) .

Oh and do not let our fooling around a bit bother you, we get a bit daffy at times.

Now I'll let LousyWeather modify my screed to fit his particular line of stoves which are more "computerized".
 

stoveguy2esw

Minister of Fire
dynamics of a burnback (aka hopper fire)

when a stove has a hopper fire generally more than one issue is at hand, one is generally a restricted exhaust air pathway either in the stove itself or in the flue. add a component failure or power outage to that and you have the ability to burn back, now, most times with modern stoves especially where more emphasis has been placed (with learning on the part of we manufacturers us included of course) this still can be avoided in all but really bad cases of neglect. the inherent design of a drop feed is usually not prone to burnback as when feed is cut there is a built in separation between the feed tube and the fire. now a blocked exhaust path allows fuel to pile up against the chute which "reconnects' the fuse to burn back. in a bottom feeder such as my stoves in the event of a bottom auger failure or power outage you do have fuel right at the fire but this fire has a lot longer transit to the bin due to the 2 auger system which gives almost a foot of tube before you get to the drop chute which is internal, now there is separation in between the top and bottom augers that is actually protected from "stacking" as its separate from the burn chamber. also the feed system is heavily gasketed which is quite important as i will explain later.

pellets as we know need air to burn, when our stove gets dirty enough we see this in the ash in our burn pot (half burnt pellets look like little burnt rat turds) this works to our advantage in protecting from a burn back. this is why i BEG people to practice good gasket maintenance! our feed systems are sealed for this reason, if a situation mechanically happens (power outage, component failure etc) the last (and arguably most effective) line of defense is the robust gasketing of our feed systems. this in essence prevents "air replacement" which is necessary to sustain the fire, so what happens is the fire dies from lack of air before it gets back far enough to cause any mischief. even our top feed stoves are gasketed this way, as are virtually all pellet stoves.

now getting back to the airway for the exhaust; the flue system equipped with a vertical rise even if it is not above the roofline due to the small amount of draft cause by the residual heat in the flue (Bernoulli's principle, though Boyle's law plays a part as well. makes for interesting reading if you have a few weeks to burn brain cells at a rapid pace) short version is that a column of air at a higher temperature than the air surrounding it tends to rise (fundamentals of what makes a woodstove burn) this will keep the air moving on the path we want it to follow. without this, air will not have flow, when air doesn't flow and heat is present it simply expands, pushing in whatever direction provides the least amount of resistance (remember our gaskets?) if the path back through the feed system provides less resistance this is where the airflow will travel, right back through into the bin.

short version is this; if a person is not going to be dedicated to the upkeep necessary to allow a pellet or multifuel unit to perform at its peak, and here is the important part, to also work as intended under ABNORMAL conditions, such as power outages , component failures and the like, literally every pellet stove sold in the US will be able to put itself out properly without risk of hopper fire, the testing all of our units,industry wide, mine, harmans, quads , cab 50's and everyone in between undergo to be given a UL listing assures that regardless of brand you will have a unit which if properly maintained will not leave you with a hopper fire.
That said, any pellet stove can be a victim of a hopper fire if neglected, so lets keep em clean folks, practice good PM, pay attention to your gaskets, replace if its not serviceable even if it doesn't seem like it matters it does or we wouldn't put it there, gaskets cost money, if we didn't need em we wouldn't spend the money on em so we could sell em cheaper, right?

i hope folks find this educational, i can talk about it much easier than type it so if my essay seems disjointed i apologize. i can go into greater detail but im hoping just the basics will suffice
 
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