Runaway fire question

[mbk2000]

I'm doing some searches on "runaway" stove fires, but not able to find a basic explanation of what constitutes a fire out of control. Seems that some folks mention temperatures above 700 but I'd like to know how to really identify when there is a true emergency situation. Yesterday, I wasn't paying attention and let the stove peg out at 900 (flue temp 550). I closed the stove damper and it came down quickly enough. Maybe I should have worried.
So what exactly is a runaway fire please?

 

[swestall]

Stack temp over 900 and you can't shut it down. Stove top at over 900 and you can't get it down in 15 minutes. 700 is within the operating range of most stoves. Having said that, I've inadvertently had it up to 900 for a "while" and not dammaged the stove, stack or anything else: sure was hot though.
My biggest concern is if there is creosote in the chimney and it catches off one of these HOT fires and then you have a problem if there is any appreciable creosote build up.

 

[Byron]

I just finished installing my stove (Hearthstone Homestead) a couple days ago and also have a questions regarding stove temps. My stove's manual says the surface temperature should not exceed 600 degrees. I've yet to get it above 350, which heats the room to 86 degrees. When the stove is at 350, the sides of the stove are significantly hotter to the touch (i.e., I burn the crap out of my hand if I touch the side). Is it normal to have such a disparity in temperature between the top and sides of a soapstone stove?

Thanks, and Happy New Year!

 

[swestall]

I've recently been doing some research on Soapstone stoves. I'm told that the exterior of the soapstone will get up to about 500 degrees or so, while the interior of the stone will absorb a lot of heat and the internal temps will be over 1000 degrees. The soapstone will continue to emit heat consistently after the fire dies down because of that.
If the secondary burn is going, you should be fine: and it sounds like you are not having a problem heating the house at all.
The hearthstone site has a great writeup on how this entire process works.

(broken link removed to http://www.hearthstonestoves.com/soapstone.shtml)

 

[burnham]

I just finished installing my stove (Hearthstone Homestead) a couple days ago and also have a questions regarding stove temps. My stove's manual says the surface temperature should not exceed 600 degrees. I've yet to get it above 350, which heats the room to 86 degrees. When the stove is at 350, the sides of the stove are significantly hotter to the touch (i.e., I burn the crap out of my hand if I touch the side). Is it normal to have such a disparity in temperature between the top and sides of a soapstone stove?

Thanks, and Happy New Year!

Wow. I've got my Mansfield crankin' at 600 degrees (top and sides are the same temp), and my house is only 73 degrees. I guess it's time for some new windows. I'll keep an eye on the top and sides and let you know what she does.

 

[Byron]

You are most definitely heating a larger area than I am. My stove is sitting in a 170 sf room, with two adjoining rooms (275 sf and 135 sf, respectively) also getting heat. The room with the stove in it is where I'm taking the air temp; each of the adjoining rooms is in the mid 70s. Heat from the stove, unfortunately, does little to nothing to heat the front part of the main floor of my house (which is about 600 sf) or the upstairs (another approx. 600 sf). I know it's too much stove for the space I'm heating, but it beats room where the stove now resides being 59 degrees just about every morning. I had originally plannned to use the stove in the front of the house (in front of my fireplace) where it is more open and the heat could rise to the upstairs; however, I ran into all sorts of problems making clearances and did not want to, for aesthetic reasons, take out my wood mantle. I'm now sort of rethinking the whole setup and wondering if I'd be better off with a small stove (maybe a Jøtul F 100 Nordic QT or Jøtul F 602 CB) in the back part of the house and then either making the changes I don't want to the make the the front of the house and then moving the Homestead, or maybe selling the Homestead and getting an insert. In the meantime, there's no shortage of heat in the back of the house!

 

[mbk2000]

Stack temp over 900 and you can't shut it down. Stove top at over 900 and you can't get it down in 15 minutes. 700 is within the operating range of most stoves. Having said that, I've inadvertently had it up to 900 for a "while" and not dammaged the stove, stack or anything else: sure was hot though.
My biggest concern is if there is creosote in the chimney and it catches off one of these HOT fires and then you have a problem if there is any appreciable creosote build up.

Ok, that helps. But I'm reading in some posts that can be a real panic situation. Watching your stove for 15 minutes doesn't make it seem that dire.

 

[logmusic]

MBK:
FWIW, I think your threat level should according to the following criteria:

1. Stove Response
2. Chimney Type
2a. Chimney shape (90's?)
3. Chimney Location
4. Observation of top of stack
5. "Hand test" of walls contiguous to Chimney

It is my experience that a runaway fire is a good sign that you have a chimney fire, especially if an airtight stove is involved. Factors impacting creosote levels and volatility will be exacerbated when at the lower level of tolerances for 2-5 above. My main stove had 13' of single wall straight up through a ceiling box to double wall, Lopi Liberty at the base. i have had this puppy cranking some serious fires, but always it responds immediately. Now, my Jotul Black Bear in the basement, with 2 90' before 27' of stainless reliner inside of a masonry chimney on the outside of my house would give me cause for great concern if any fire became unresponsive. I would look at #4-5 above. Any negative finding for #5 and I'm probably calling the FD. I am considering buying one of those flare type devices that supposedly put out chimney fires just in case. My experience, as I mentioned, was growing up in an old farmhouse with chimney situations that were not good. We had a couple chimney fires growing up, but never did have to get the FD out. When the top of your chimney resembles a flare, it is time to get really concerned ;-0

I guess I cannot wrap my mind around the idea of a runaway fire absent some sort of chimney anomaly when using an airtight stove in general.

Good luck friend.

 

[rudysmallfry]

The good thing about the Hearthstone stoves is that if you aren't paying attention to a rapidly building fire, you get alerted by the smell of overheated cast iron. If I smell that, I know my stack is approaching 500 and have plenty of time to shut it down.