Symptoms of a Chimney Fire?

My daughter's room is upstairs from the room with our insert, and the chimney runs through her closet. This evening when I was getting her ready for bed, her rooms felt unusually warm. I felt the wall behind which the chimney runs, and the plaster wall was warm to the touch -- I checked against another interior wall, which was cold to the touch. Inside her closet, the upper section of the wall next to the chimney was quite warm. Not hot like hot water from the faucet, but very warm. I read about the symptoms of chimney fires, and went outside just not to see if there were any flames/heavy smoke coming out the chimney, but fortunately none. I don't think this was a chimney fire, but what else could this be from?

Background:
Vermont Castings Montpelier insert, installed in a 1900 masonry fireplace. We had it installed this past October, with a full stainless 6" steel chimney liner. The installer wrapped some kind of insulation around the liner before running it into the chimney. He installed block off plates at the top and bottom. We've been running the insert a lot this week, as the temperature was a daytime high of 15 and nighttime low of 5 or below. We had a very hot fire this afternon, as I just scored a bunch of 2 year old oak.

I've burned about 2 cords of wood since we got the insert installed. 1 cord of this was well seasoned, and 1 cord was sold to me as "seasoned", but I've since learned it was quite green, about 30% moisture content. The oak I just picked up today was 11%. Anyway, it's certainly possible that the green cord created some creosote, but I tried to run the fire hot and mix it in with the well seasoned wood.

Any ideas? I'm letting the fire run out tonight (it's down to mostly ashes right now), and I'm planning to call the chimney sweep to come inspect/clean. Any one seen similar symptoms and have some idea to share?

BotetourtSteve said:

How hot are you burning your stove? Even with above-average moisture, a hot fire will cure a lot. Have you heard a roaring sound in the stove/flue (a classic sign of a fire)? With the liner you had installed (assuming it was done correctly), there shouldn't be much to worry about as far as a structure fire, but I can understand you pulling in a sweep to check things out.

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When we first got the insert and I was new at this, I would turn the air all the way down after it got good flames.
Recently (last month+) we've been burning it hot, air full on for first 30-60 minutes after we load the wood, then down to about half-way until bed time. Last 3 days, I've been running it as hot as possible.

I haven't heard that kind of roaring sound, but I'll admit the fan's been running load so I might have missed it.

BotetourtSteve said:

It'll cost you a few bucks, but piece of mind can be priceless sometimes!

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indeed. But i hate to not run a fire when it's 10 degrees outside. :long:

cmonSTART said:

I doubt its anything to worry about but its probably wisest to have your sweep come and check it out just in case. Sounds like a good install!

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I've been thinking about it some more.... Could it be that the stove got really hot, and the outside of the stove heated the air/bricks in the chimney (outside the liner) -- not smoke, just hot air in the cavity inside the chimney but outside the liner? Maybe the masonry in that section of the chimney has cracks, and the heat escaped into the wall cavity? I'm just casting about.

fbelec said:

i've been in a lot of old house like your houses age and older. those old chimney had no clay liner so any amount of heat in the chimney comes thru the wall. also some people in the old days plugged up chimney holes from old stoves with the plaster that is your finished wall. if the plaster feels and sounds really solid that might be you. and you want to replace those bricks.

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That makes sense, that the plaster wall inside the closet might be plastered right over the bricks.
How would I even find out if that's the case?
I thought the liner + insulation would make the old masonry chimney irrelevant.

Indeed it was warm and not hot, and this morning (fire long since out) the plaster wall was cold as expected. There's no attic above that part of the house -- the room is in a craftsman-style front-to-back gable with a shed dormer giving it 8' headroom (see picture below, right-hand side of house). The chimney goes through the closet and then the roof, and as you see in the picture it extends about 8' from there (to be above the ridge of the main roof). So if any heat was radiating up outside the liner, it would make sense that it would trap there, e.g. below the top block off plate.



I'll call the chimney sweep tomorrow, and hopefully they can come yet this week. Do you think it's safe to use the stove in the meantime? I just got almost 2 cords of very well seasoned oak just waiting to use it!

pen said:

Last 3 days, I've been running it as hot as possible.

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What do you mean by running it hot as possible? Do you mean leaving the primary air fully open all of the time? Do you have a thermometer on your stove top? Or on exposed single wall chimney?

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Thursday-Friday-Saturday were our coldest days of the year so far, with nighttime temps in the 0 degree range and we had significant wind gusts so windchills in the -10 or -20 range. For these 3 days, I was loading the stove more often, maybe every 2 hours (rather than waiting until there were only small coals left), and leaving the primary air at about halfway or a bit more all the time. It was producing great heat

No, I don't have a thermometer on the stove.

firefighterjake said:

Random thoughts:
I am a big fan of thermometers . . . both the stove top and flue thermometers. They help keep your temps in the Goldilock Zone -- not too hot (risk of damaging the equipment), not too cold (risk of causing creosote build up) and keep things "just right." Without some type of thermometer it's kind of hard to tell when a fire is hot, really hot or way too hot.

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Thanks. I'll look for one...

firefighterjake said:

My guess . . . probably not a chimney fire. None of the classic signs . . . but why risk things . . . buy some peace of mind and have a competent chimney sweep do an inspection of your chimney. Pay a little now, pay a lot less in the future . . . in other words, it may cost a bit for a full inspection now, but an inspection now is a heckuva lot cheaper than rebuilding a home and having to buy all new stuff if there is a fire.

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Indeed. The installer/sweep is coming by Tuesday morning to clean/inspect and discuss what happened. I'll report back on what I learn.

firefighterjake said:

Fuel . . . ah, the first year burner's lament of having less than ideal wood. There are many threads here offering some advice on what you can do for better burning . . . not best burning . . . but better burning (i.e. pallets, splitting smaller, "speed" drying, etc.)

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Ain't that the truth. It takes a lot of learning to figure out what "seasoned" wood looks like, how to judge, etc. I've learned so much over this first season: not to trust vendor's description, how to use a moisture meter, how to haggle with the guy who says he's got seasoned wood but shows up with stuff registering 30% moisture on the outside, and how to recognize a deal when you find one. Now I've got 2 cords already stacked for next year, so I know it'll get easier.

So the chimney sweeps came out today. After running the brush in the chimney liner, there was only about 1-2 cups of debris -- so obviously the fire's been hot enough and not too much buildup/creosote. Definitely no chimney fire here. Phew!

I described to the the hot wall upstairs, and they said that the liner would be hot, but that the insulation would prevent the brick chimney from getting hot. I suggested to them the idea about the heat radiating up from the stove, around the liner and they said no -- there's a block-off plate for prevent that. Well when they took the surround off the stove to double-check, I took a look with the work light and saw a gap of about 3" by 8" on one side of the flue collar. That might be how some heat got up outside the liner. So they filled in the block-off plate with some of the fireproof insulation (looks like R13 but it's white). We'll see if that prevents the hot wall symptoms.

Since I'm only gonna burn about another 1-1.5 cords this season, they told me to have them back after next season, in May/June 2011. Thanks for all the ideas!