Chimney Fire - Is it Possible with a Selaed Insert?

[TnAndy]

For some reason my flue does not build up much but I do get a build up on the bottom (inside) of the flue cap. Have not figured that out yet.

Most likely you have one of the newer gassifier type stoves, they are extremely clean burning and produce very little creosote because they recirculate the smoke/gases and reburn them. But I've found the same thing....the problem area is the top cap. It only seems to happen in really cold (for here) weather...like teens and below. My theory is that cap is ice cold, and the only place for whatever is left in the exhaust to condense. Ours builds up to the point it shuts off the draw of the flue, and I know when to hit the roof because we start getting a smoke smell in the house.

 

[KennyG]

No exp. with chimney fires as I keep it fairly clean, but what does a guy do if he has one and throws some suppression material in it. I really doubt it will knock all the flames out so how would a guy deal with hot burning logs at that time. Just leave it and hope it all goes out then take care of it???

I've never had to use mine, but I understand that it will create enough CO2 to smother the chimney fire and cool down the stove fire. To ignite the creosote you generally have to be hotter than a moderate stove fire. You are supposed to throw in the suppressant, close the air intake damper and keep the stove closed.

 

[Coyote machine]

I've never had a chimney fire with the 3 fireplace stove inserts at my house. I do keep a chimfex and other bottle type extinguishers on each level of the house to cover any type fire. I had a SS liner inserted into the chimney which consisted of several sections screwed together and it went directly into the top of the various wood stove fireplace inserts we've had over the last 30 years. AND, a crucial point, the chimney is a prefab unit, and where the flue exited above the roofline on the gable peak, the dual flue outlets, one for oil furnace, one for wood stove, were separate. The furnace had a metalbestos flue, the wood stove insert had the SS, which terminated, and was sealed at the metal top of the chimney stack. The prefab chimney stack was cased in vertical wood planking and the top of the entire unit had a fabricated metal flashing to keep water and wind from getting down the two flues.

Caution if sealing SS pipe at joints with caulk, only use caulk that is fire rated to withstand high temps. It is usually red in color, and is meant to be used for sealing places where a fire could go from one floor to a higher floor via electrical penetrations where there is conduit, etc. Also designed to seal flue sections - see link below; and their website has numerous tabs to select info on other hearth care and solutions.
Also note that sealing the insert stack keeps unwanted cold air out and keeps lethal gases of combustion contained so they can only exit via the top of the insert to atmosphere.
I would definitely also use heavy duty metal pipe tape to further seal any air or gases from escaping the insert where they could leak into the house.

Rutland products: https://www.rutland.com/p/3/500-degree-f-rtv-high-heat-silicone-sealant

BTW, I would have the stacks checked annually, and I burned hot fires, 850-900 degrees, and had a fire temp gauge in the stack, AND on the stove surface to monitor the situation. The wood stove SS stack/insert NEVER showed any amount of creosote and only ever needed a light brushing with a chimney sweep brush.
Trust me, the extra expense is well worth the added peace of mind for you and your family, friends using your house/cabin. Chimney fires are preventable, so do what makes sence and learn from other's experience. A chimney fire is something that kills way to many people/families when it could have been prevented in most cases.....

 

[JRobyn]

At the house my dad built in the mountains, he had a huge masonry/stone fireplace built by local craftsmen with about 30 ft. of conventional masonry flue liner up to his a-frame roof line. And he wasn't really aware of how chimney fires happen. A few years in, he had a MASSIVE chimney fire one night, with flaming chunks of creosote being carried high above the flue and landing on his composite shingle roof. Fortunately, he heard the characteristic sound of the fire and played a garden hose on the roof and the flaming chunks. Saved the house. Scary stuff.

I'm not sure if he ever had the flue checked for cracks after the event, but I bet they are cracked now.

 

[Wagtail]

Well - in my one and only experience with a chimney fire. I had very heavy duty gauntleted leather gloves. When things sort of calmed down - a lot of the smoke had cleared out of the cabin - before the smoldering wood caught on fire again - I reached in and grabbed the logs - one in each hand and threw them off the porch - out into the snow. As I remember it took three trips.

A wee bit off topic, but, I have a pair of long-gauntlet welding gloves by the wood-heater and use them to add wood with them.

One 'slip' (naturally at 3 a.m.) gave me a nasty wrist burn... never again!

 

[goeduck]

A wee bit off topic, but, I have a pair of long-gauntlet welding gloves by the wood-heater and use them to add wood with them

This is a good idea ^^

 

[goeduck]

Most likely you have one of the newer gassifier type stoves, they are extremely clean burning and produce very little creosote because they recirculate the smoke/gases and reburn them. But I've found the same thing....the problem area is the top cap. It only seems to happen in really cold (for here) weather...like teens and below. My theory is that cap is ice cold, and the only place for whatever is left in the exhaust to condense. Ours builds up to the point it shuts off the draw of the flue, and I know when to hit the roof because we start getting a smoke smell in the house.

Correct, I have a secondary air burn and cat. My temps are not as cold as yours and my buildup on the cap is not enough to block the exhaust but still it is there. Worst thing is it drips on the masonary chimney cap (flue liner in masonary chimney) and stains. I am thinking of buying a second cap and swapping it out so I can clean one on the ground good and then just swap them out. Speaking of caps curious how many have a screen on them?

 

[TnAndy]

Correct, I have a secondary air burn and cat. My temps are not as cold as yours and my buildup on the cap is not enough to block the exhaust but still it is there. Worst thing is it drips on the masonary chimney cap (flue liner in masonary chimney) and stains. I am thinking of buying a second cap and swapping it out so I can clean one on the ground good and then just swap them out. Speaking of caps curious how many have a screen on them?

Funny thing is the screen on mine is fairly large mesh opening....more to keep birds out than to arrest sparks. Diamond mesh that is like 3/4" at the wide point....but it still clogs up. I was thinking of making it taller, it's only about 4-5" tall on the mesh part....was thinking that much again, and it would have a hard time clogging up that much....maybe. My roof is really tall, and steep pitch....don't enjoy walking the ridge line !

 

[PILOON]

In some areas a screen is mandatory as a 'spark arrester'.
Sparks do fly and are known to start forest fires.
Same applies to exhausts on chain saws and ATV's.

 

[goeduck]

Here is a way to clean your chimney. Just do not put the blower on backwards.
creosote disolver - Bing video