# Volatile gas explosion- Hearthstone



## willoweep (Feb 15, 2019)

So here I am eating pizza on the couch, not paying attention to the stove. I can see there are coals, stovetop thermometer is about 250F. I didn’t know my wife had put a couple of oak blocks on the fire about an hour previous, with the air turned down about 3/4.  All of a sudden-BOOM The oak ignites in an explosion, waking the dogs, scaring wife and kids, and blowing one of the top soapstone panels up off the cast iron frame. I pushed the stone back into place, in the morning, I’ll pop all three stones out and remortar them with refractory cement. We had a smaller event like this once before, but blowing the top off the stove? I am less than impressed with the Homestead at this point. We’ve had it for five years in two different houses, run maybe 12 cords through it. While I understand there may be some operator malfunction here (incomplete combustion) it seems crazy it would blow the top off the stove! My wife is now afraid to run the stove. I’m gonna start shopping, I see an F55 or T6 in our future. Comments?


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## jetsam (Feb 16, 2019)

It is in theory possible with any stove.  I've never had it with an epa stove- but any time wood is offgassing without flame, it's possible.

It's really unlikely in a cat stove with the cat engaged, because the cat is burning the wood gas as it is produced even  without flame, as long as the cat temp is >500°.   Still, if you let the cat fall out, you could in theory get a wood gas buildup.

A tube stove doesn't have the cat, so keep the secondaries lit.

I load partial loads anytime in my stove without worry, whether it's burning high or low. On medium/high burns there is active flame, on low burns the cat is eating the wood gas.

I'd be stove shopping too if I had soapstone, but not because of the wood gas thing.


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## wooduser (Feb 16, 2019)

I hope you'll report back on how the dogs react to this over the next few days.  I'm really curious  ----will they keep one eye open?  Not sleep in their customary position/posture?


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## fire_man (Feb 16, 2019)

Ever since the Progress blew its top open (literally) years ago, my alleged dog never slept with both eyes closed near the stove again.

The stove had no damage, probably because the hinged lid blew open and relieved internal stress. Its never backpuffed that bad since I added about 2 feet to the stack.

And I love the soapstone


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## EbS-P (Feb 16, 2019)

I generally add a piece or two of poplar or pine kindling first and last if my stove top is below 325. Primary reason is that it lights the secondaries quicker but as an added benefit it would reduce the likelihood of detonation. It’s happened to me a time or two first time I was using the ash pan door to get wet wood going (yes I knowthat’s a no no). The other time I reloaded at about 275 and with air closed not on purpose , I was trying to pack it tight and the reload took longer than usual. I closed the door. Then opened the air up and THWUMP.   So now I always start with kindling first.  Mistakes happen important thing is  to lean from them. I did, no more ash door and use kindling.   

I like the T4 in white, but I also love my Jøtul. That would be a tough one for me.


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## moresnow (Feb 16, 2019)

I am thinking of a Domino's Pizza commercial. Did yours end up upside down on the floor?

Or stuck to the ceiling!

Poor dogs!

All in good fun!


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## kennyp2339 (Feb 16, 2019)

We had this happen with my parents steel insert a few years ago, my mom through on of those thin balsa like clementine crates on coals, about 5 min later the whole insert shook and was really loud, also created a small smoke condition in the living room.


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## Sawset (Feb 16, 2019)

There is a lesson to be learned here, one that requires no emotion or a rash of decisions. Fresh fuel, on hot coals, and no air, means volatile gasses ready to go off. In 10yrs here it's happened 3 times. Twice in the first year. I can blame that on inexperience. And once 3wks ago, under the exact same circumstances you mention, minus the pizza. A reminder that I was " not paying attention to the stove". Don't put leaves, sticks, kindling, and in my case a bucket of woodshop cutoffs, on hot coals without giving it air and a flame. A stove in the house brings along a few fairly defined set of responsibilities. The family here talks openly about them, and is aware. But not afraid. We burn 24/7 6mo out of the year. Let this just be a heads up.


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## lsucet (Feb 16, 2019)

When I read this last night, I can't stop just laughing cause of the way the OP said it. The eating pizza part is hilarious.
Thanks God nothing happened but after so many post is funny how some are more concern about the dogs and not him and his family.


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## Riddlefiddle (Feb 16, 2019)

Happened to me last year. Turned air down too much and kablooy! Smoke everywhere. Smoke detector going off and all. Learned my lesson quick man.


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## begreen (Feb 16, 2019)

Yes, you want some flame when turning down the air and don't let the fire smolder. 
FWIW, this can happen with almost any wood stove given the right conditions.


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## toddnic (Feb 17, 2019)

We've had that experience a couple of times with the Progress Hybrid. It definitely "wakes you up" when it happens.


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## webby3650 (Feb 17, 2019)

We have had a few hearthstones blow their top this season. True it can happen in any stove, but only a Hearthstone stove is fatally wounded when this happens. As you found out, there’s very little holding those stones down, it’s a fragile design. At least when they crack, a small explosion will dislodge then so they are easier to change!  
I would also start stove shopping.


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## webby3650 (Feb 17, 2019)

We actually joke around at work about how every Hearthstone should come with safety goggles and a flak jacket! Hearthstone, home of the exploding stones!


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## begreen (Feb 17, 2019)

Better to relieve pressure by lifting a stone than blowing out the door glass as was reported here years ago.


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## brenndatomu (Feb 17, 2019)

Yup, you heat with wood long enough, this will happen with any stove sooner or later...basically boils down to operator error...although some model stoves and installs seem more susceptible to it than others...


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## begreen (Feb 17, 2019)

brenndatomu said:


> Yup, you heat with wood long enough, this will happen with any stove sooner or later...basically boils down to operator error...although some model stoves and installs seem more susceptible to it than others...


Yes, this can happen more often with a downdraft stove when draft is weak and the fire needs more air.


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## webby3650 (Feb 17, 2019)

begreen said:


> Better to relieve pressure by lifting a stone than blowing out the door glass as was reported here years ago.


As was mentioned, this happens somewhat often. Rarely ever is there any damage to the stove, except a Hearthstone, it just can’t handle it.


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## Highbeam (Feb 17, 2019)

brenndatomu said:


> Yup, you heat with wood long enough, this will happen with any stove sooner or later...basically boils down to operator error...although some model stoves and installs seem more susceptible to it than others...



It’s never happened to me. I suppose we’re not average users though.


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## brenndatomu (Feb 17, 2019)

Highbeam said:


> It’s never happened to me. I suppose we’re not average users though.


Well I think you have your air control lever welded in the wide open position...and I'm not sure this can happen with the air wide open


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## begreen (Feb 17, 2019)

Highbeam said:


> It’s never happened to me. I suppose we’re not average users though.


As I've mentioned in the past this happened to me once with the Castine with some damp maple. It was a serious explosion. Won't happen again.


brenndatomu said:


> Well I think you have your air control lever welded in the wide open position...and I'm not sure this can happen with the air wide open



LOL So did I. Still can happen.


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## Highbeam (Feb 17, 2019)

As we gain experience, the wood gets so dry that the dang stuff is flaming before you can even shut the loading door. Backpuff averted.

Now on the bk, the thermostat will actually close and open the intake valve far enough to cause repeated flame ignitions as it modulates. These ignition events look cool but are never violent.

I wonder if wet wood is the root cause for those that see violent flame burst backpuffs.


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## webby3650 (Feb 17, 2019)

My Lopi Leyden would do this, bad enough to blow the top lid open! Pretty scary! I’ve had a puff that would escape the door gaskets on a few stoves, but nothing serious.
We are about to rebuild a half season old Hearthstone Mansfield here soon. It blew the top so bad that cement chunks flew across the room!


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## willoweep (Feb 17, 2019)

I’m happy to report back that everyone is fine. The dogs are back to sleeping in front of the stove, and I’ve been reading some of the responses back to my wife. Obviously a bit of operator malfunction, but my wife’s response “it’s a wood stove, I should be able to put wood in it without it blowing the top off” is kinda on the money, too. Fortunately, there was a half a five gallon bucket of refractory in the garage, the repair was NBD. Pull off the stones, clean old mud with the grinder, clean cast iron frame, mud the frame, back butter the stones, drop them in, beat them flat with the rubber mallet and 2’ level. Then wait an hour, small fire, let it cool to room temp. Then fire it up! Glad the stones or glass didn’t break. It is just that1/8” refractory joint holding the lid on these stoves. We’re only half way through the season here, I’m glad I can keep this running for now.


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## webby3650 (Feb 17, 2019)

willoweep said:


> I’m happy to report back that everyone is fine. The dogs are back to sleeping in front of the stove, and I’ve been reading some of the responses back to my wife. Obviously a bit of operator malfunction, but my wife’s response “it’s a wood stove, I should be able to put wood in it without it blowing the top off” is kinda on the money, too. Fortunately, there was a half a five gallon bucket of refractory in the garage, the repair was NBD. Pull off the stones, clean old mud with the grinder, clean cast iron frame, mud the frame, back butter the stones, drop them in, beat them flat with the rubber mallet and 2’ level. Then wait an hour, small fire, let it cool to room temp. Then fire it up! Glad the stones or glass didn’t break. It is just that1/8” refractory joint holding the lid on these stoves. We’re only half way through the season here, I’m glad I can keep this running for now.


It didn’t have Stainless splines between the stones? Hearthstone uses a specialized refractory  cement that is made with soapstone dust. It’s really good stuff. You may consider rebuilding the top this spring with their cement.


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## willoweep (Feb 17, 2019)

Yes, the stainless splines were there. They seemed pretty well cemented into the center stone so I left them in place, and buttered the joint underneath them. We’ll see how it holds up the rest of the season. My mud was Heat Stop, leftover from a masonry firebox rebuild. I’m just happy that we are burning again and not waiting 3 weeks for parts from Hearthstone. I’ll look into their mud this summer.


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## firefighterjake (Feb 19, 2019)

Put just about any combustible on to hot coals with little to no air and you'll get a build up of gases . . . just waiting to get hot enough to ignite and them KA-BLAM . . . results may vary, but typically there will be a bunch of smoke coming out of the stove, stove pipe, etc. and while not common, there can be damage to the stove or stove pipe.

It was cardboard for me.

It's an easy fix though. Leave the air control open when adding fresh fuel. I typically leave my door ajar as well . . . but that's mainly because I'm the impatient sort who wants a fire sooner rather than later.


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