Was this a chimney fire?

[MJFlores]

Hi everyone....this morning when leaving for work, I noticed a bunch of black stuff in the driveway, and directly under the chimney in the snow. Some background...I have a Woodstock Fireview, and the chimney has a stainless / insulated liner. I burn dry wood...and sometimes toss in scraps of kiln dried pine to start it if I dont have an ember. I do get my chimney professionally swept and inspected once a year, for peace of mind and to maintain my lifetime warranty for the liner. I've been burning for the past month, what I'd consider good and dry wood. My stove is a cat stove...so rarely the stove will sit there burning, and all of a sudden the cat will ignite ause what I call a "mini explosion" in the stove...it's only once every few years....you'll hear a "woof" from the stove, maybe smell some smoke, and you'll see a nice cat lit fire for a while in the stove. I mention this because it's the last thing I recall out of the ordinary happening yesterday. Again, this is rare...I've had the stove 17 years and it's maybe happend 5 or 6 times. Anyway, what is this soot in the yard? I opened the stove top and looked in it and as far into the pipe as I could...looks clean enough with no visible creosote (I realise that's likely to build up near the top where it's cooler). So anyway, things were working fine...but now I'm nervous to light the stove. Was this a chimney fire? Or did that cat event blast a bunch of crap out of the chimney. I'm what I consider "In tune" with my stove, and I never heard or felt anything strange last night. Due to a warm front coming in, I let the stove burn down so when I went to bed there were just red coals in there. I just want to get people's opinions on what I saw outside in the snow.

 

[begreen]

Sounds like you are having small puffbacks occasionally, perhaps from turning down the stove a bit too low? That may have blown out crap from the chimney. Are you using any cardboard to start fires?

 

[Ludlow]

Shotgun! Just makes sense if the stove had an explosion that it would have blown the flaky stuff out like a shotgun. No chimney fire as you have your explanation for the deposits.

 

[MJFlores]

Sounds like you are having small puffbacks occasionally, perhaps from turning down the stove a bit too low? That may have blown out crap from the chimney. Are you using any cardboard to start fires?

Never card board...I prefer to nurse an ember back to life so I often never use anything...if it's stone cold I'll use a small amount of news paper, with mostly fine pine and hemlock kindling to get it going. I do try to keep the air low...perhaps too low? Thanks for pointing that out.

 

[MJFlores]

Shotgun! Just makes sense if the stove had an explosion that it would have blown the flaky stuff out like a shotgun. No chimney fire as you have your explanation for the deposits.

Thanks...is the "explosion" a normal thing of running a CAT stove? I assume it is, because the science makes sense to me...when there's enough smoke fuel,...and the CAT finally ignites...woosh! It's neat but a little concerning at the same time. So, that junk I found outside is likely nothing to worry about? I like having the chimney swept towards the end of the season, so I know it's ready to run for the following season. I'm tempted to have it checked out just in case but if what I saw is normal I'm OK...I never heard anything strange. As a child, I heard what a chimney fire sounds like in a fireplace and I'll never forget that sound...or smell.

 

[Dieselhead]

Expansion/contraction of the metal liner will loosen up deposits and they have no place to go but up and out when the chimney is drafting. I see some flakes occasionally also.

 

[weatherguy]

I've had the whoosh a couple times with my PH.

 

[Ludlow]

Thanks...is the "explosion" a normal thing of running a CAT stove? I assume it is, because the science makes sense to me...when there's enough smoke fuel,...and the CAT finally ignites...woosh! It's neat but a little concerning at the same time. So, that junk I found outside is likely nothing to worry about? I like having the chimney swept towards the end of the season, so I know it's ready to run for the following season. I'm tempted to have it checked out just in case but if what I saw is normal I'm OK...I never heard anything strange. As a child, I heard what a chimney fire sounds like in a fireplace and I'll never forget that sound...or smell.

I dont know about cat stoves. Just makes sense if there was an explosion that debris would be expelled. I would be confident that is your reason for the flakes.

 

[peakbagger]

I will also qualify that I dont have any experience with catalysts. My guess is its turn down situation where the stove is "blacking" out from insufficient air being introduced to keep up with the amount of wood being gasified . The catalyst just lowers the temperature for ignition of the gases, if there is not enough air the gases will still not burn. The gases are still warm so they head up the chimney until they find enough oxygen to ignite. A flame front travels rapidly down the stack to the stove but the only place the gases can go is up the stack. It would knock any loose deposits out the stack. If you had sticky or solid creosote it would stay in the stack.

Definitely a worth a phone call to the manufacturer.

 

[barnaclebob]

Its not the cat igniting but the stove slowly getting to the right combination of fuel, oxygen and heat. I get it on my Progress Hybrid if I shut the air control down at the right time to get an all cat burn. Its the same phenomenon that causes backdrafts in house fires I believe. It does it with enough force to rattle the heavy top.

Maybe you had a backpuff that traveled up the chimney.

 

[Dieselhead]

Smoke is unburnt fuel. When enough of it builds up in the firebox and conditions are just right it can light off. Known as a smoke explosion it happens even in house fires when conditions get just rich enough and the temperature is there to ignite the unburnt airborne particles.

 

[EbS-P]

one of my favorite demonstrations of this.

Smoke is unburnt fuel. When enough of it builds up in the firebox and conditions are just right it can light off. Known as a smoke explosion it happens even in house fires when conditions get just rich enough and the temperature is there to ignite the unburnt airborne particles.

 

[begreen]

Thanks...is the "explosion" a normal thing of running a CAT stove? I assume it is, because the science makes sense to me...when there's enough smoke fuel,...and the CAT finally ignites...woosh! It's neat but a little concerning at the same time. So, that junk I found outside is likely nothing to worry about? I like having the chimney swept towards the end of the season, so I know it's ready to run for the following season. I'm tempted to have it checked out just in case but if what I saw is normal I'm OK...I never heard anything strange. As a child, I heard what a chimney fire sounds like in a fireplace and I'll never forget that sound...or smell.

It can happen when the flame dies and the wood is smoldering, filling the firebox with wood gases. Then, if a flame reappears, it ignites the wood gas with a mini-explosion. Not normal and you want to avoid this. Burning partially seasoned wood is a possible cause as well as weak draft. How tall is the chimney? When was it last cleaned? Is there a screen on the cap?

 

[MJFlores]

one of my favorite demonstrations of this.

WOW...thats an amazing video. I wonder what it looked like outside when this occurs in a woodstove? It must blast out all the loose particles in the chimney...clearly what happened here in my case. Thanks for posting that...truly amazing.