My first runaway fire

[newburner]

Holy cow. Today, I cut up some oak pallets to supplement my wood. I read a lot here that pallets are good, cheap heat.

I put 3 pallets boards in with a couple of splits and had no problem. When that died down, I added 3 more pallet boards and the thing took off! Within minutes, the entire box was ablaze. The bottom half of the glass and the firebricks all turned black. The fire looked like it was actually coming from the door gaskets. I turned the air all the way down but it just wouldn't subside. I found myself trying to remember everything I've read here about this situation but all I could do was stare and hope for the best.

After a few minutes, it died down to the point where I felt comfortable opening the door to throw in a split. The split burned as usual and it cleaned the glass and firebricks completely.

I'm a bit nervous about the pallet burning now.

 

[Dix]

Do you have a thermometer on this stove / insert?

If so, what were the temps?

 

[EatenByLimestone]

I wonder if the door wasn't sealed completely shut. Maybe an ember got trapped in the seal?

 

[KindredSpiritzz]

wet newspaper is my plan if that ever happens, never tried it before but its the only thing i remember

 

[BrotherBart]

Entire firebox ablaze ain't no thing. A over heated stove is. Dry pallet wood on top of hot coals is gonna blast off. Rest, you didn't have a problem. Now if it kept doing it for a half hour, which a couple pallets pieces ain't gonna do, then you have a problem.

Scares you too much, just swing the door all the way open and let the inrush of cold air knock it down.

 

[Offset]

Entire firebox ablaze ain't no thing. A over heated stove is. Dry pallet wood on top of hot coals is gonna blast off. Rest, you didn't have a problem. Now if it kept doing it for a half hour, which a couple pallets pieces ain't gonna do, then you have a problem.

Scares you too much, just swing the door all the way open and let the inrush of cold air knock it down.

I know this is going to sound really stupid but here goes. I read before in one thread or another about opening the door wide to slow the blaze down. As you mention above in your reply that is what you would do and yet it seems counter to what you want to do. If you shut down all the controllable air and it does not respond how does opening the door to huge volumes of air knock the fire down. I don't for a moment disbelieve what you are saying just trying to understand the principal behind it.

 

[prezes13]

I know this is going to sound really stupid but here goes. I read before in one thread or another about opening the door wide to slow the blaze down. As you mention above in your reply that is what you would do and yet it seems counter to what you want to do. If you shut down all the controllable air and it does not respond how does opening the door to huge volumes of air knock the fire down. I don't for a moment disbelieve what you are saying just trying to understand the principal behind it.

It's not going to knock the fire down. What is going to do is get the cold air from your room and go straight to the flue. That will cool the the firebox off.

 

[EatenByLimestone]

It also could push flame up into your flue... If dirty, that could start am chimney fire.

 

[tarzan]

Do you know what the stove top temp was when you added the pallet wood?

I agree with BB that you likely didn't have an overfire but thin, dry pallet wood on a good bed of hot coals can look impressive.

 

[branchburner]

how does opening the door to huge volumes of air knock the fire down...
just trying to understand the principal behind it.

Think about an open fireplace... huge volumes of air pass through, but the draft is diffused and not focused, so the fire does not burn out of control. Huge volumes of cool room air are being sucked up the flue along with the smoke and flames of the fire itself. So while some of the additional air acts as fuel for combustion, a larger portion of it acts as a check on the fire.

 

[branchburner]

I'm a bit nervous about the pallet burning now.

You'll get over it... for now, just continue to put 2 or 3 pallets boards in with a couple of splits and have no problem. After all, it's only when you added 3 more you got a flash fire.

And a brief flash fire is not really always a "runaway" or overfire even though it looks scary. If you monitor both your flue and stove top temps you will know when to get scared and when not to. A quick spike in stove temps over 700f is no longer of any concern to me, and it happens all the time. SUSTAINED temps that push 800f would be a problem... but I would only expect that from a full load of pallet wood, not from a few pieces added in with splits.

 

[begreen]

It's not going to knock the fire down. What is going to do is get the cold air from your room and go straight to the flue. That will cool the the firebox off.

Actually it can knock the fire down by breaking the negative pressure in the firebox and thus temporarily interrupting secondary combustion. Often after doing this, then closing the door, the fire settles down into a normal burn.

 

[prezes13]

Didn't think about it that way. Good point begreen.

 

[begreen]

I stumbled on this by accident with the F400. After a reload on too hot coals I was too slow to turn down the air. The fire built up steam and stove top quickly approached 750F, I opened the door considering removing a log or two, then thought better of that silly plan. When I closed the door, the bloom of wood gas had passed up the chimney and the fire settled down into a completely normal burn.

 

[prezes13]

It's a very good point especially for the beginners when you have to do something opposite to what your intuition tells you to do. Last thing you want to or think of doing is get more air into the fire. But when you think of it it make sense.

 

[begreen]

Yes, it is a bit intimidating. That's why I tell most folks to just ride it out and not repeat the same mistake.

 

[CenterTree]

I stumbled on this by accident with the F400. After a reload on too hot coals I was too slow to turn down the air. The fire built up steam and stove top quickly approached 750F, I opened the door considering removing a log or two, then thought better of that silly plan. When I closed the door, the bloom of wood gas had passed up the chimney and the fire settled down into a completely normal burn.

It also could push flame up into your flue... If dirty, that could start am chimney fire.

What do you guys think about the open door approach in regards to it causing a chimney fire? (assuming there is even sufficient enough creosote build up in the first place)

 

[begreen]

Not sure if it would be more susceptible than with an already very hot flue. The bloom released by opening the door is short, while a raging stove is no. My guess is that if conditions are ripe for a chimney fire to happen, it's going happen regardless.

 

[oconnor]

I know this is going to sound really stupid but here goes. I read before in one thread or another about opening the door wide to slow the blaze down. As you mention above in your reply that is what you would do and yet it seems counter to what you want to do. If you shut down all the controllable air and it does not respond how does opening the door to huge volumes of air knock the fire down. I don't for a moment disbelieve what you are saying just trying to understand the principal behind it.

What you are doing is cooling the flue. If you truly have a runaway stove, then you have too much draft for the heat and fuel load in the firebox. A minute or two of open door burning can cool off the flue temp significantly, which, when you close the doors again, means the burn rate will slow down. That is also what the rolled wet newspaper does - converting water to steam takes lots of energy from the flue gasses, cooling them down.

Remember, your flue is what runs the stove - cool it and the stove will slow down.

 

[FionaD]

Opening the door does feel a weird thing to do, but it has worked for me on the two or three occasions I've done it.. the most recent being just yesterday. A combination of the stove burning really fast due to very high winds and me getting distracted for just a few minutes resulted in a 850F stove top. Luckily it was just a small load, four small splits on some coaled kindling, just getting a stove going again. I did the classic thing... got distracted by an email, intending to 'just check' for two minutes....!

....rushed back in the room and opened the door. Flames immediately changed shape (best way I can put it) and temp stared to fall immediately.

That the hottest I've ever had. Didn't like it one bit. But opening the door definitely saved the day and my shredded nerves!

PS... Hello O'Connor in Nova Scotia, from Auld Scotia!

 

[Offset]

I really want to thank you all for the explanation of why and how the opening of the door works. The more information we have the safer and more effective we can be at running the stoves. This site is a treasure trove of information.

Appreciated very much.

 

[BrotherBart]

I had to discover the door thing by accident a few years ago. Had a runaway tagging a thousand degrees and not looking like it planned to slow down. Finally did the only other thing available, swing the door wide open, and the temp started sliding down when the vacuum to the secondary tubes and doghouse air was broken.

One thing to watch out for is popping embers when the cold air hits the load. Also don't just crack the door open a little or you will just make things worse.

 

[Sprinter]

Also don't just crack the door open a little or you will just make things worse.

Right. You don't want a blast furnace, just an open fireplace, and only for long enough to cool things down a bit which shouldn't take long.

I'm glad to see several real life successful experiences with this. So far, I haven't had to test the theory myself... But it always made sense to me at least theoretically. Everyone seems to have a favorite way to cool an overfire, from wet towels to this.

I wouldn't be uncomfortable about burning dry oak anymore. You now know how not to

 

[newburner]

I wouldn't be uncomfortable about burning dry oak anymore. You now know how not to

Thanks for the responses. I think the thing that caused the most concern was that to date, I have been unable to close the air any lower than 75% without extinguishing the fire. When this happened, I had the air all the way closed and the fire seemed to get bigger. Eventually, I couldn't even see "fire". The glass was just a glowing panel of orange. It looked as if someone painted the glass with hunter orange then put a spot light behind it.

I fiddled with the air control thinking it was broken and when I slid it all the way to the open position, the orange turned white. Then back to orange when I closed the air down.

As someone new to this, it was quite unnerving.