I would find it very odd that a fire department would not respond to a chimney fire?
As for your 1st question, why would you question response time in regards to a chimney fire??
We have an large rural area where 15 miles is not uncommon. and many chimney fires are still burning when we would arrive on scene.
The bags of dry chemical was more convenient because of the cost of recharging an extinguisher was eliminated.
This question was not not posed by me.
In my experience chimney fires were over in about a minute, so do the math time-wise: first discover the fire, then have the presence of mind to call 911, then wait for the guys to gather @ the station, then wait for them to arrive at the residence, so F.D. response time is a valid concern. In my cases, the excitement was all over 30 minutes before the F.D. could have possibly arrived, at best.
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Interesting. Apparently some stack fires last longer than I have experienced. Thank you for your insight.
However your upthread statement: “Discharging a dry chemical extinguisher into the firebox is very effective also.” and my question: For a chimney fire? remains un-addressed. Yeah, the firebox may:rolleyes: be suppressed, but the chimney?
The dry chemical does in a chimney fire just what it does in every fire its used on, by interrupting the chemical reaction of the fire triangle,
which means smothering the fire.
That is also what water in the firebox will do when it turns to steam.
And what if the fire has already worked its way out through a crack in the chimney (which it may have created) and into the rafters?
I’d strongly recommend cleaning the chimney. Much better not to have the fire in the first place, than to have it because you thought you could count on putting it out easily.
When I worked for Servpro, we got called out to do a dryout and clean up from a chimney fire. Damn quickly too, the Fire Dept was still there putting out the half of the attic that burned through a hole they cut in the roof. Clean yer stack people, a few hundred dollars pounds euros pesos rubles whatevers is well worth the thousands saved in damage costs. And there is nothing shittier than having all of the insulation taken out of the attic and a whopping big hole in your roof right over the living room in the winter. Chimney fires are sneaky bastards, someone already said it, you don’t have a problem until suddenly you do.
Most all chimneys (Masonry) have a flu liner either preformed in <>3’ sections or the popular Slide Casting systems.
The liners help prevent buildup and protect the masonry blocks from extreme heat.
You quoted me in the What If, well that is why our area always responds Code 3 to all fires because of the possibility of further damage. And like i posted earlier, building materials can, with exposier reduce their auto ignition temp.
I remember one chimney fire, it was in a metal-bestos chimney where the insulation had started to oxidize and i called down from the attic for a pitcher of water and suppressed that one.
I excised below what you mistakenly attributed to me that should actually be part of your post #23.
Again, thanks for the insight. No offence taken.
Well, sometimes. It is not controlled exclusively by the amount of oxygen. Fuel and heat are also prime factors. If no indication of flame is evident coming out of the stack, it should be obvious that one of the three factors necessary for combustion (fuel, heat, oxygen) are deficient to maintain a full blown chimney fire. This doesn’t discount the possibility of a smoldering potential in the stack for further combustion, but it significantly diminishes the possibility of raging fires 30 or more minutes after initiation when the fire department manages to show up .
I will flat out say you are wrong concerning barometric draft controllers. It is the rare occasion where in house barometric dampers are employed in wood stoves, and furthermore it is generally accepted that they are a dangerous mis-application of technology for in home wood stoves that are actually designed for oil and gas boilers. As you mention, if such a device is employed on a wood stove, a chimney fire would be exacerbated by a barometric damper because of it’s design flaw in dumping more oxygen (draft) into the stack during a fire, not to mention it’s propensity of shunting carbon monoxide into the living area. My chimney fires were loud, but I save the jet engine reference for when I’ve been drinking;). I’ll also ask for cites that verify sustained 3000 degree stack temps during a fire… heck, even instantaneous temps of this magnitude. Under the conditions we are all familiar with here, this sounds unreasonable.
Come on.:rolleyes: Let’s keep in mind the finite amount of fuel, oxygen, and residual heat available 30 minutes after the chimney fire’s inception. The initial heat would be the greatest, and the residual smoldering heat would be much less. Were you guys using plastic chain? I worked in the electrolytic steel industry pulling broken electrodes from a molten bath of metal with chains, (the chains would be red to white hot and stretch like hell lifting thousands of pounds) and certainly at higher temps than an exhausted chimney fire, but with no problem… so you’re saying your chain melted in a relatively exhausted/cooled wood stack fire by simply suspending a couple of pond ball?
Yeah, I get the fire triangle concept.
My question was related to how DRY CHEMICAL application to a firebox would have significant affect on a stack fire. Use of dry chemical extinguishers to put out a firebox is not disputed here… My question is to your assumption as to it’s effectiveness on extinguishing a CHIMNEY FIRE. In my experience dry chemical extinguishers are very effective in suppressing appropriate fires in-situ,(such as the firebox) but ** not** for associated residual fires (such as the chimney).
Unlike dry chemicals, water in the firebox will indeed create steam, rising into the stack, extinguishing flue fires.
At work we use steam for extinguishing duct/stack fires in susceptible areas because steam avoids the time transition problems between liquid water and steam, and the fact that steam instantaneously deprives combustion of necessary oxygen.
In RE the OP:
Not rocket science here…Just close off your air control. If the fire remains too hot, you have an air leak, (gasket issue.)
Wouldn’t dumping water in the overheated firebox risk cracking the stove, thereby not only ruining the stove but also allowing the fire to escape directly into the living quarters?
I suppose anything is possible. The conditions are so variable, it’s difficult to say with certainty exactly what may happen. I’ve doused stoves with water that were running flat out (in non-panic situations) and never had any problems, though it usually caused some creosote to drop out of the stack onto the stove baffle, which I took as a good thing… better there where I could remove it before I fired up again, than have it remain stuck in the stack. YMMV
I posted; [[Originally Posted by Gbro View Post
Most systems have a barometric draft damper Here This device needs to be closed off or the fire in the chimney will sound like a jet engine and will burn at over 3,000 deg.]]
I did error on the temp, but 2,000 deg is not unheard of.
As for the Barometric draft damper, they certainly were used back in the 1980’s and i still have one on my wood cooking stove in my cabin. A dedicated chimney for the wood stove was not seen very often and of course this could be a huge factor in the high volume of chimney fires.
Discharging the dry chemical extinguisher into the fire box was very effective at knocking down the raging fire just as bombing the fire with bags of same.
The huge asbestos mittens we wore when chaining or using a 10 lbs grinding ball attached to a chain, had leather palms, but were still clumsy. No other PPE would work when handling that chain that could and would melt off if left in the flu too long.
Insurance carriers started to drop policies if the wood stove and chimney didn’t pass inspection.
Stoves with gaskets on the doors were unheard of and it wasn’t uncommon to see home built wood stoves. (the ones without the UL sticker) Lol!
You certainly have a different reconciliation of the 1970’s and early 1980’s than I do.
Every stove I was acquainted with at that time definitely had door gaskets, and definitely did not have a barometric damper.
If it was over in about a minute, it probably wasn’t a proper chimney fire. Having e.g. flue gas ignite for a few moments is a very different scenario from a sustained tar/creosote fire.
The typical damage scenarios for a chimney fire are for it to burn through metal liners and/or masonry chimney stacks, or heat the stack to such a degree that it autoignites surrounding timber/insulation. That’s generally not going to happen in ‘about a minute’.
It’s anecdotal at best, but a lot of old-timers swear by burning aluminum cans to keep creosote down. I’m not sure what the chemical reaction involved is, but since the general consensus seems to be “well, it’s not going to hurt anything,” I usually throw one in any time I’m using the stove in my workshop. It’s new this season, though, so there hasn’t been enough time to see if it makes a difference.
I’d like to ask a question of my own: in all my research, I haven’t been able to find out how big a fire should be. I know you don’t want to get your stove glowing, but short of that, can a fire be “too big?”
(By “new this season,” I mean a new installation. The stove itself is about 25 years old, and is the older, dead simple “firebox with a stovepipe out the top” design. It’s secondhand, so there’s no manual to refer to.)
Get a stove thermometer. (It’ll have a magnet, to keep it stuck to the stove or the stovepipe; and be designed to withstand the heat.) It’ll probably have cold/good/overhot zone markings as well as temperature in degrees; those zones are usually calibrated to stovepipe temperatures, and the top of the stove can be hotter than that, but it’ll give you some idea.
FWIW my Lopi is supposed to have the bypass control (which forces gases over the secondary burn pipes, and which your stove probably doesn’t have) put in at 300ºF, ordinarily burns most of the time at between 400º and 700ºF, and shouldn’t get much over 750ºF, measured on the top of the stove on the lower potential cooking area; but it really is going to depend on the stove, as stove constructions vary. If you know the make and model of yours, you may be able to find information online, or at a stove shop.
By “too big” my assumption is you are referring to too hot. If so, the answer is no.
Barring the extreme you mention of glowing, (which is a little more difficult to achieve than one may realize) any properly designed and maintained woodburner (stove) is capable of safely running maxed out for extended periods of time. Typically, once the area is warmed up, the air is cut back till the stove output is reduced, and just maintains a comfortable area temperature.
OP is running a 25 year old box stove, which may or may not have been either properly designed or properly maintained. I’ve certainly gotten one of those glowing hot without particularly trying, years ago when I didn’t really know what I was doing. I didn’t burn the house down, but it still wasn’t a great idea.
Even a stove which is properly designed and maintained has to be designed for an average sort of load of wood – a stove that will burn moderately dry maple well enough to not clog the stovepipe may well overheat if fed with a load of extremely dry old locust posts and left to run wide open for extended periods of time.
It also may be designed for an average sort of chimney draw. Some chimneys draw better than others, and will pull more air through the stove at a given setting than others.
A followup related question if you don’t mind.
I just replaced the seal on my oven. The door does not seem to be closing tightly. The seal is quite round now.
Does these things “flatten out” in a reasonable period of time? Like before Friday when we will be doing our Thanksgiving thing.