Chimney Fire Jitters

[mvubike]

So, we had what we suspect was a relatively minor chimney fire. Now I feel like I'm on high alert all the time and I'm kind of nervous whenever we have it running... which is always.

Here's the particulars:

• New insulated stainless chimney installed up through the middle of the house. Installed mid October and used almost daily since
• External Chimney is at peak and extends a good 3'
• Pre Cat VC Intrepid in good shape. Airtight except for a tiny speck of light at the top of the gap in two front doors when closed
• Double walled black pipe with two 45 degree elbows (picture)
• Kiln dried hardwoods
• Use some pine scrapes when starting

So, last weekend I restarted the fire in the AM on a 40 degree morning and got it going to the point where I could close the flue and throttle back the damper. I headed out to the barn to start working on projects. Had a fire going in the Jotul 602 out there too! Came back in about 1.5 hours later and noticed the wife had the door cracked on the front of the VC and it was blazing! Immediately went over and shut the door, flue and damper. You could hear some burning "activity" and crackling in the pipe and and I was freaked out. Then there was smoke starting to come out of the junction of the black pipe and stainless pipe. Not a ton but it was noticeable. Called 911 just to be safe. The black double wall elbow closest to the top started to discolor as the noise and smoking died down. The noise was gone by the time the FD arrived 4-5 minutes later.

After they took a look, they asked me all the questions that the particulars above are the answers to. I let it die down and pulled the black double wall section. There was some creosote flakes in the there and you could see where it had been burning in that upper elbow. Looking up through there was some larger deposits at the seams in the stainless sections but nothing major. At it's worst the build up was a couple mm deep. It was mostly loose flakes.

I had this stove growing up and I like to think I know how it should run. I like to get a good bed of coals and then back it off to burn slowly without smoldering. I've resigned myself to pulling the black pipe monthly to inspect it. I feel very gun shy about letting her rip and I'm wondering if any of this raises a red flag for some of you more experienced folks out there.

One last thing to note that I'm currently trying to remedy. The section of pipe that attaches to the stove is a little funky. The crimped/tapered end that was part of the telescoping section that should have fit inside the stove hole was just too big to fit. I found that I could pull apart the two section of that telescoping piece and it fit snuggly, if not perfectly airtight around the outside of the pipe. There's no noticeable air suction sounds coming from there that would leave me to believe that air id being introduced to the flue at this spot. Regardless, I'm going to try and get the guys at the stove shop to get me set up with an appropriate adapter with the crimp/taper I think it needs.

Hit me with your thoughts,
Freaked in Maine

 

[rippinryno]

having the door cracked with blazing fire probably wasn't a bad thing but likely ignited the fire you think you heard. Did you notice anything coming out of the chimney? Are you certain there was a creosote fire or could something have crawled in or settle in from the top of the chimeny? A critter or anything that may have caused this burn and also caused your smoke leak inside? it may have been a creosote fire, but your buildup sounds very minimal and most folks probably have more than that in their chimney right now as we speak.

 

[begreen]

Although the original VC designs were advanced for their day, they were not all that clean burning. If the stove has been run low and slow since Oct. due to mild weather, then it is not surprising that there would be some build up. Has a cord of wood been burned? That would be a good starting point for cleaning interval.

This stove has shorter than normal legs. The hearth setup does not look good for heat protection under the stove. Is there a heat shield under the bottom of the stove?

 

[mvubike]

having the door cracked with blazing fire probably wasn't a bad thing but likely ignited the fire you think you heard. Did you notice anything coming out of the chimney? Are you certain there was a creosote fire or could something have crawled in or settle in from the top of the chimeny? A critter or anything that may have caused this burn and also caused your smoke leak inside? it may have been a creosote fire, but your buildup sounds very minimal and most folks probably have more than that in their chimney right now as we speak.

I cleaned it tip to tail after the scare and there was no foreign objects in there, just the aformentioned minimal build up. The fact that I saw the elbow start to change color fro a deep black to a more brown black is what leads me to believe there was a fire in the double wall pipe. The Plus, in that same area, on the inside of the pipe, there was what appeared to be a concentrated (melted?) patch of black material. The smoke coming out of the chimney looked normal and whispy and maybe a little thicker than usual for the composition of the burning materials in the woodbox.

 

[mvubike]

Although the original VC designs were advanced for their day, they were not all that clean burning. If the stove has been run low and slow since Oct. due to mild weather, then it is not surprising that there would be some build up. Has a cord of wood been burned? That would be a good starting point for cleaning interval.

This stove has shorter than normal legs. The hearth setup does not look good for heat protection under the stove. Is there a heat shield under the bottom of the stove?

I've gone through about a half cord. It's 10 out right now and I have a good hot burn going to keep it warm in the house so that may be the difference needed to keep it cleaner.

I have 2 sheets of 1/2 cement board under the soapstone as per your advice from 9/22/15 BeGreen!

 

[begreen]

LOL Sept. was a thousand posts ago. I don't recall short legs being mentioned in that posting, but maybe they were. How warm is it getting under the stove?

 

[mvubike]

LOL Sept. was a thousand posts ago. I don't recall short legs being mentioned in that posting, but maybe they were. How warm is it getting under the stove?

It's cranking right now and I can hold my hand under the stove. The soapstone gets nice and warm as I had hoped but not anywhere near too hot to touch.

 

[bholler]

its hard to tell from your description wether or not you had a chimney fire. Was there any creosote in the chimney that had bubbles in it? what did the buildup look like?

 

[claydogg84]

The real question is why did your wife have the door cracked with the stove blazing? It's an older stove so some buildup is expected in the chimney. You may have just heard the sound of the pipes expanding and contracting from reaching such high temperatures. I had a similar occurrence more than once with my VC Defiant...

 

[mvubike]

its hard to tell from your description wether or not you had a chimney fire. Was there any creosote in the chimney that had bubbles in it? what did the buildup look like?

The build up was flaky and scaled the side of the pipe. The Fireman said it was a small chimney fire and that shutting down the air as much as possible was the right thing to do.

 

[mvubike]

The real question is why did your wife have the door cracked with the stove blazing? It's an older stove so some buildup is expected in the chimney. You may have just heard the sound of the pipes expanding and contracting from reaching such high temperatures. I had a similar occurrence more than once with my VC Defiant...

Absolutely. In a way this was a good thing. She had maintained that "she knew what she was doing" having had woodstoves growing up in MN. She has a new found respect for the stove and thankfully we got lucky her inattention didn't end up costing us dearly.

 

[begreen]

I strongly recommend keeping a kitchen timer or cellphone timer set and nearby anytime the stove door is left ajar. It's too easy to get distracted and lose track of time.

 

[rippinryno]

i have a question. Can a stove actually get itself into trouble if the door is left open or if the vents are left open? On my stove, depending on what kind of heat i demand I will leave my flu vents on the front wide open before shutting them down by night. This burns a very hot and fast fire, but it does tend to blast more heat out when the blower is running. I'm curious if a stove should be able to get itself too hot by leaving the door open too far? Heck, sometimes when mine is really ripping i'll open the door to scavenge some of the heat into the room. Also, what kind of heat protection is needed under a stove? I have mine sitting on bricks so it is merely inches away from the concrete floor,e nough for me to sweep under it. that being said i can put my hand under the stove when it is at full heat and the floor is barely warm.

 

[mvubike]

I strongly recommend keeping a kitchen timer or cellphone timer set and nearby anytime the stove door is left ajar. It's too easy to get distracted and lose track of time.

My favorite part of having a woodstove is sitting in the rocking chair enjoying a beer/coffee as it gets going. Seems to be the perfect amount of time to get it to the point where i can close it down and walk away.

Prior to the "incident" I had been giving mumma some lip about shutting down the stove too soon after adding logs causing it to smolder. Naturally, that was her initial defense. I'll leave it cracked for a minute on the second load of wood till I see it start to burn, but never long enough for it to start going crazy like she did. I certainly hope she's learned her lesson. I never walk away or leave the room with the door cracked open...

 

[mvubike]

i have a question. Can a stove actually get itself into trouble if the door is left open or if the vents are left open? On my stove, depending on what kind of heat i demand I will leave my flu vents on the front wide open before shutting them down by night. This burns a very hot and fast fire, but it does tend to blast more heat out when the blower is running. I'm curious if a stove should be able to get itself too hot by leaving the door open too far? Heck, sometimes when mine is really ripping i'll open the door to scavenge some of the heat into the room. Also, what kind of heat protection is needed under a stove? I have mine sitting on bricks so it is merely inches away from the concrete floor,e nough for me to sweep under it. that being said i can put my hand under the stove when it is at full heat and the floor is barely warm.

I actually tried something along these lines last night. After a long day of burning wood (I was working from home due to the first snow storm of the season) I had a deep bed of coals. We have the intrepid specific spark screen so I opened it up and started adding one small log at a time and watching burn with my feet up. Quite nice. When we first started having fires i tried this same technique but when there were still a few good size logs in the middle of their burn. It started ripping pretty good... a little too good, so i shut it back down and hadn't tried again till last night.

After posting this I've started looking around for flue temp gauges. Any recommendations?

Leaning towards this one
http://www.condar.com/Probe_Thermometers.html

 

[bholler]

Can a stove actually get itself into trouble if the door is left open or if the vents are left open?

yes you can easily over fire a stove that way or pull flames into the stack which can light off a chimney fire.

On my stove, depending on what kind of heat i demand I will leave my flu vents on the front wide open before shutting them down by night. This burns a very hot and fast fire, but it does tend to blast more heat out when the blower is running. I'm curious if a stove should be able to get itself too hot by leaving the door open too far? Heck, sometimes when mine is really ripping i'll open the door to scavenge some of the heat into the room.

With your setup you probably have allot less draft than you should so you may be able to get away with it better than people with a proper chimney and enough height. Leaving the door open is very dangerous due to both fire and co risk.

Also, what kind of heat protection is needed under a stove? I have mine sitting on bricks so it is merely inches away from the concrete floor,e nough for me to sweep under it. that being said i can put my hand under the stove when it is at full heat and the floor is barely warm.

That depends on the stove in your case you dont need any because it is on concrete

 

[rippinryno]

thanks for the answers bholler much appreciated! My stove actually does get a ton of draw now, with 5-6ft vertical inside, and another 8ft vertical outside. I think specific to the design of the nashua stove, it would be tough to draw flames much into the chimney since it would have to get through 2 elbows plus the way it is designed inside the firebox it has to burn up and around a baffle then out the back and by that point I'd imagine there are no flames to make it out to the chimney. I could see how a straight up chimney could pull a flame really high. I do often check the surface temp of my stove pipe as well as the top of the stove. At full blast with a huge bed of coals and the vents wide open I typically am around 500 degrees at stove top and the same temp at the first stove pipe coming out of the stove. My stove doesn't seem to benefit from air draw when the door is open, it seems to really take off when i close the door and have my 2 knobs wide open, the air sucks right into the bottom where the coals are and really let's it rip. One thing i am still alwasy curious about is the surface temp of my class A through wall pipe. that sucker gets hot to the touch and holds that heat until the stove is pretty much out. I have a proper wall thimble and the wall and structure is never hot to the touch, just makes a guy wonder how hot the exterior of that class A should get.

side note: i cleaned all my stove pipe and chimney yesterday. The outside seems to look just fine, i did notice the first elbow out of the back of mys tove had some of the brown fluffly creosote, nothing major but i did go ahead and clean all the pipes anyway. suprisingly the outside single wall pipe looked better than the elbow right out the back. I'm thinking some of my wood was not fully seasoned.

 

[bholler]

it would be tough to draw flames much into the chimney

yes but most chimney fires start in the pipe. And actually a fire in the pipe is still considered a chimney fire.

At full blast with a huge bed of coals and the vents wide open I typically am around 500 degrees at stove top and the same temp at the first stove pipe coming out of the stove.

If that is all the higher your temps go at full blast that tells me you have either or inadequate draft

 

[rippinryno]

yes but most chimney fires start in the pipe. And actually a fire in the pipe is still considered a chimney fire.

yes, but my point was that a stove with a flu running straight form the top will inevitably have fire going directly into the pipe. What i was implying is that my stove is not setup like that so the flame has to travel and make 2 turns before it can even get to a piece of pipe. A stove with a flu directly on top will have flame going right into the flu and stove pipe especially when it's going hard.

If that is all the higher your temps go at full blast that tells me you have either or inadequate draft

Would the fact that there is a blower blasting air through channels that go right below the stove top have anything to do with cooler stove top temps. The blower disperses the heat straight out the sides of the stove. it blows around the fire box as designed and really throws a lot of heat! I've been told by several stove guys that this stove is very efficient for the year. I can't imagine how my stove would have inadequate draft at this point, especially since i've extended the external vertical pipe. It seems to draw very well, i've not had smoke come back since i exteded it above roofline outside. the temps of my fire inside the stove are plenty hot!

 

[bholler]

yes, but my point was that a stove with a flu running straight form the top will inevitably have fire going directly into the pipe. What i was implying is that my stove is not setup like that so the flame has to travel and make 2 turns before it can even get to a piece of pipe. A stove with a flu directly on top will have flame going right into the flu and stove pipe especially when it's going hard.

Most stoves unless they are really basic old smoke dragons have some kind of baffle and yes even with a baffle flames often reach the pipe and i am sure yours do to. if there is enough draft to pull them there.

Would the fact that there is a blower blasting air through channels that go right below the stove top have anything to do with cooler stove top temps. The blower disperses the heat straight out the sides of the stove. it blows around the fire box as designed and really throws a lot of heat! I've been told by several stove guys that this stove is very efficient for the year. I can't imagine how my stove would have inadequate draft at this point, especially since i've extended the external vertical pipe. It seems to draw very well, i've not had smoke come back since i exteded it above roofline outside.

Yes but if at full blast all the higher your pipe temp gets is 500 then there is something not right. Especially with a big old beast like you have if left wide open you should reach 1000 pretty quickly. Not that you should run it up that high but the fact that it wont do it tells me something is not right

 

[rippinryno]

Most stoves unless they are really basic old smoke dragons have some kind of baffle and yes even with a baffle flames often reach the pipe and i am sure yours do to. if there is enough draft to pull them there.


Yes but if at full blast all the higher your pipe temp gets is 500 then there is something not right. Especially with a big old beast like you have if left wide open you should reach 1000 pretty quickly. Not that you should run it up that high but the fact that it wont do it tells me something is not right

it's actually a smaller stove compared to most that i see. I just took some temps from it after 5 hours of hedge and maple burning and with 50% hedge, i was below 600 at the pipe and the stove. If i open the stove all the way up it will burn hot and fast. I do not have the adjustment knobs set to open completely but they are pretty far out on the max setting. i typically have them 50% of the way open for a constant burn, keeps it plenty hot and burns complete.

 

[rippinryno]

After reading threads about flu temps and stove top temps i'm wondering about the advice you have given bholler. How hot should my pipe or stove top be do you think when i'm running a full stove? After talking with a stove guy and reading on here it seems my temps are right where they need to be.

https://www.hearth.com/talk/threads/stove-pipe-temperatures.56910/

also, when lighting a new fire and especially when getting things going, you can certainly expect flames to go into a stove pipe, i don't see how any stove, especially older stoves can prevent a flame tip to get into some of the piping....unless you turn it down. I personally let my fires get very hot before i dampen things down a bit. You obviously don't want flames raging out the top of the chimney but you cant' tell me that flames don't reach the initial stove pipe on a regular basis on all stoves and fireplaces.

 

[bholler]

After talking with a stove guy and reading on here it seems my temps are right where they need to be.

Well 500 is a little hot to run at all the time but what tells me there is something wrong it the fact that you said that is all the higher it will get even with the air wide open. If you let the air wide open and you have good wood and a proper setup your temps would be much higher than that. The fact that yours is not tells me something is wrong. Also what did the stove guy say about the fact that you were using stove pipe as a chimney? If he was ok with it he is not a reputable stove guy i am sorry.

also, when lighting a new fire and especially when getting things going, you can certainly expect flames to go into a stove pipe, i don't see how any stove, especially older stoves can prevent a flame tip to get into some of the piping....unless you turn it down. I personally let my fires get very hot before i dampen things down a bit. You obviously don't want flames raging out the top of the chimney but you cant' tell me that flames don't reach the initial stove pipe on a regular basis on all stoves and fireplaces.

Yes flame do reach into the pipe at times on most stoves i never said that they didn't in fact i said it did. The actual definition of a chimney fire is fire in the venting system more than 18" from the appliance. So it is expected to a certain extent

 

[bholler]

After reading threads about flu temps and stove top temps i'm wondering about the advice you have given bholler. How hot should my pipe or stove top be do you think when i'm running a full stove? After talking with a stove guy and reading on here it seems my temps are right where they need to be.

if infact those temps are with the stove shut back and are taken right at the stove then i agree they are right. If I misunderstood you previously i apologize. but

 

[rippinryno]

Also what did the stove guy say about the fact that you were using stove pipe as a chimney? If he was ok with it he is not a reputable stove guy i am sorry.

"keep an eye on that" were the exact words, lol. I told him i've cleaned it twice and he said as long as you dont' let the creosote buildup in there and don't expect it to last very long that it can work lol. I've already picked up 2, 36" sections of class A for outside, currently still need a class A Tee and I need to figure out a way to support them from the building once i install them. This will be done during the summer for next season.