Keep that chimney clean

[begreen]

Burn dry wood and clean the chimney. This sad tale happened to a fireman's home yesterday. Fortunately, no one was hurt but the home was a total loss.

Fire destroys Nisswa assistant fire chief’s home

Joe Hall, his wife and four children escape unharmed; home is a total loss

www.pineandlakes.com

 

[PA452]

Stories like that are certainly sobering. We're building a house right now with a wood-framed chase containing flues for two wood stoves. It's got me a little nervous just because I'm not used to a setup like that.

I grew up cutting firewood and we burned a lot, but it was a masonry chimney that was very overbuilt. My parents actually had more than a couple chimney fires that I can remember and it held each time. Looking back, they did pretty much all the wrong things with their fireplace.

 

[joop]

glad all his firefighting courses helped ,not

 

[webfish]

Pretty close to my cabin. Nisswa was/is a great little vacation town . Changed a lot since the 70s though .

 

[moresnow]

Pretty close to my cabin. Nisswa was/is a great little vacation town . Changed a lot since the 70s though .

The entire area has changed big time. Unrecognizable in many respects.
Good luck to the FF who lost his home. Glad all are safe.

The guys may not let him live this one down for a while.

Betcha pipes are getting cleaned area wide.

 

[peakbagger]

There were quite a few fires reported in the Northeast this weekend. My guess is we had about a month of warmer than normal weather which means stoves were being idled leading to creosote buildup. Then a cold snap comes through the area and everyone goes in full throttle heating mode and the previous build up lights off?

 

[joop]

it's possible,but that would be pretty quick buildup.older stove ?

 

[bholler]

it's possible,but that would be pretty quick buildup.older stove ?

What do you mean?

 

[stoveliker]

He means that having enough build up in a chimney after a one-month mild weather burning would be "pretty quick".

That is true. But building up crud that quick is possible, especially with wetter wood.
Modern stoves do fairly well (not being able to run very low by design), but even when one uses wood that's too wet, modern stoves can also gunk up a chimney. And do so quickly.

 

[begreen]

Modern stoves do fairly well (not being able to run very low by design), but even when one uses wood that's too wet, modern stoves can also gunk up a chimney. And do so quickly.

Indeed. Several years ago I had a run-in with wet maple. The stacks had gotten wet in places due to a leaky tarp. It was all we had to burn. This wood gunked up our flue system in 3 weeks. Fortunately, I caught it early enough to avoid a chimney fire, but this is the dirtiest our flue has ever been. Now, if the wood is not ready, we won't burn. We now have a proper wood shed and this has not happened again.

 

[Woody Stover]

The guys may not let him live this one down for a while.

I first thought "Well, they look pretty smiley about the whole thing." Next thought was "Or maybe somebody just said 'Hey, chief, when was the last time you swept your chimney?' " 😏 To which he replied "I never sweep, I just burn it out." 😆

 

[kennyp2339]

Fire doesnt care, if you allow conditions to exist that promote fire growth, your creating a potential accident. Just before the snow hit on Monday, I threw the ladder up and inspected the chimney and cap, I ended up brushing the cap a little bit, but visually checking the chimney to make sure it was free and clear of buildup is mental insurance.

 

[fire_man]

Stories like that are certainly sobering. We're building a house right now with a wood-framed chase containing flues for two wood stoves. It's got me a little nervous just because I'm not used to a setup like that.

I grew up cutting firewood and we burned a lot, but it was a masonry chimney that was very overbuilt. My parents actually had more than a couple chimney fires that I can remember and it held each time. Looking back, they did pretty much all the wrong things with their fireplace.

I know just what you are saying about "overbuilt". Ours is a 6'x3' chimney with only one flue, which is offset towards the outer chimney wall. Physics says no way can there be a problem with clearance to combustibles causing a fire, but code is code so I insulated it.

I have to wonder, are most chimney fires caused by sparks dropping on the roof or improper clearance to combustibles around the chimney? I'm betting it's the former by far, so a better code would insist on fireproof roofing.

 

[kennyp2339]

I have to wonder, are most chimney fires caused by sparks dropping on the roof or improper clearance to combustibles around the chimney? I'm betting it's the former by far, so a better code would insist on fireproof roofing.

Almost all the house fires I've been to that have started from chimney's have been from the exposure catching fire from radiant heat from the chimney, either cracked masonry, class a pipe failure (old pipe that has become compromised, then fails)
Don't think I recall any roof fires that have started from sparks, embers, or expanded creosote.

 

[fire_man]

Wow, a class A pipe failure? So the two layers of stainless steel were corroded thru?

Would you suspect in this case it sounds like a roof fire caused by sparks/embers when it was described in the article this way “The roof was burning off,” he said. “Upon my arrival, there was significant smoke and flames from the roof area."

 

[kennyp2339]

Wow, a class A pipe failure? So the two layers of stainless steel were corroded thru?

Would you suspect in this case it sounds like a roof fire caused by sparks/embers when it was described in the article this way “The roof was burning off,” he said. “Upon my arrival, there was significant smoke and flames from the roof area."

That’s the thing, fire can start on the outside of a house, go unnoticed, hit the soffit and enter the attic still unnoticed and then self vent through the roof grabbing everyone’s attention between the bright flames, heavy smoke, crackling noises and sounds of light weight trusses failing and hitting the ceiling below.

 

[fire_man]

That’s the thing, fire can start on the outside of a house, go unnoticed, hit the soffit and enter the attic still unnoticed and then self vent through the roof grabbing everyone’s attention between the bright flames, heavy smoke, crackling noises and sounds of light weight trusses failing and hitting the ceiling below.

This makes sense, but it's easy for me to picture how expanding creosote and embers shooting out the stack like a volcano can burn thru asphalt roofing and start a roof fire as a primary cause, but I'm no expert. From what you posted earlier, it sounds like most house fires are not due to chimney fires, but more likely from compromised liners during a normal burn.

What I don't understand is how can insulating a SS pipe help if the root cause of the structure's fire is due to a comromised liner? The insulation is meant to prevent combustible material nearby from reaching ignition temperature from a super hot pipe while the chimney fire is raging . If the liner is compromised, I would think it would burn thru the thin insulation.

 

[EbS-P]

This makes sense, but it's easy for me to picture how expanding creosote and embers shooting out the stack like a volcano can burn thru asphalt roofing and start a roof fire as a primary cause, but I'm no expert. From what you posted earlier, it sounds like most house fires are not due to chimney fires, but more likely from compromised liners during a normal burn.

What I don't understand is how can insulating a SS pipe help if the root cause of the structure's fire is due to a comromised liner? The insulation is meant to prevent combustible material nearby from reaching ignition temperature from a super hot pipe while the chimney fire is raging . If the liner is compromised, I would think it would burn thru the thin insulation.

so your assumption of the liner failure as the initial point of origin I understand but…. A chimney fire is the point of origin. If pyrolysis has occurred is lowers the combustion temperature of the affected combustibles. Through repeated high temperature exposures. The could happen with a liner that is still functionally intact but missing insulation awhile being run within design limits. Thick 1000 degree liner touching masonry that is touching combustibles.

So now if a chimney fire happens the wood is not already charred and can withstand higher temperatures before it catches in fire. Buying you egress time and time to put out the chimney fire.

Look if your liner is compromised the insulation will help a bit to contain flue gases but that’s not the design. It’s designed to work with an intact liner not a backup for liner failure.

 

[bholler]

I know just what you are saying about "overbuilt". Ours is a 6'x3' chimney with only one flue, which is offset towards the outer chimney wall. Physics says no way can there be a problem with clearance to combustibles causing a fire, but code is code so I insulated it.

I have to wonder, are most chimney fires caused by sparks dropping on the roof or improper clearance to combustibles around the chimney? I'm betting it's the former by far, so a better code would insist on fireproof roofing.

Physics and real life experience says say most fires from chimneys are due to lack of clearance to combustibles. Usually at the wall passthrough but it absolutely happens at the chimney

 

[bholler]

From what you posted earlier, it sounds like most house fires are not due to chimney fires, but more likely from compromised liners during a normal burn.

Absolutely not. The temps are typically not high enough to cause ignition through the masonry under normal operating temps.

And generally it has absolutely nothing to do with a failed liner. In most cases I have seen the liner is fine. And it won't burn through ceramic wool. The insulation may tear if the liner actually fails but it won't burn through it.

 

[bholler]

Wow, a class A pipe failure? So the two layers of stainless steel were corroded thru?

Most class a failures aren't from both wals of stainless rusting or burning through. They are from compromised insulation or failed connections. I just cleaned one last week where the inner wall and insulation was almost all gone from the tee and first section of pipe. The customer said oh yeah pieces came out a couple years ago but it was still working fine🤦‍♂️🤦‍♂️

 

[fire_man]

Absolutely not. The temps are typically not high enough to cause ignition through the masonry under normal operating temps.

And generally it has absolutely nothing to do with a failed liner. In most cases I have seen the liner is fine. And it won't burn through ceramic wool. The insulation may tear if the liner actually fails but it won't burn through it.

Ok so bottom line , Chimney fires cause extreme excess heat radiated from an intact liner, and the insulation protects the combustible structure from the short term excess heat. Long term, the insulation prevents pyrolysis so when a chimney fire does occur, the wood has a higher ignition temperature to start with. I'm surprised sparks,embers aren't a big problem.

What are you referring to when you say "wall passthrough"?
"Usually at the wall passthrough but it absolutely happens at the chimney"

 

[bholler]

Ok so bottom line , Chimney fires cause extreme excess heat radiated from an intact liner, and the insulation protects the combustible structure from the short term excess heat. Long term, the insulation prevents pyrolysis so when a chimney fire does occur, the wood has a higher ignition temperature to start with. I'm surprised sparks,embers aren't a big problem.

What are you referring to when you say "wall passthrough"?
"Usually at the wall passthrough but it absolutely happens at the chimney"

Where the crock passes through a combustible wall to get to the chimney. They are almost never done properly

 

[kennyp2339]

Ok, so let me explain compromised in my definition: any condition other than what the manufacturer intended.
I've been to fires that started from older zero clearance units, homeowners never thought of hey this thing is 20yrs old, lets inspect it, instead they made a fire and unknown to them, the chase was leaking for the last 10yrs and part of the units chimney became rotted and had a small hole.
Masonry chimney fire - homeowner thought he was old school, he wouldn't clean the chimney manually, instead he would light a big fire and burn creosote out, turns out the last time he did it, unknown to him he cracked his flue tile, had regular fire since, then did one of his maintenance hot burns and well, the crack let to much heat through and the attic rafters started on fire.
Class a pipe - hopefully no fire but a poster here posted pics of: I was cleaning my chimney and noticed warped metal inside my chimney pipe, I should be good for the rest of the season right? well thats inner pipe failure, in the event of chimney fire or stove over fire with hot flue gasses that could be the point of failure and travel into the structure.
A chimney fire from creosote build up can reach temps up to 2,100deg f, thanks to draft within itself, it acts like a torch, sometimes when we roll up to a chimney fire it looks like a roman candle, most times the house isnt hurt from these fires since both masonry and class a, or liner w/ insulation does its job as intended and installed within spec, but at the end of the fire we will condemn the chimney, follow up with fire prevention / marshal and at a minimum the chimney would need to be inspected and signed off by a certified specialist before its used again.
I'd write more, but I literally have a fire call