Just learned that creosote buildup burns at 2,000 degrees

Found this in an NFPA report after a guy in my local sweep group posted photos of a chimney fire last week. That's hot enough to warp a stainless liner in about 30 seconds. Anyone else keep a thermometer gun to check flue temps mid-job?

3 comments

3 Comments

the_felix5d ago

Actually, that 2,000 degree number is a bit off for most standard chimney fires. The NFPA report you're thinking of probably references the maximum possible temperature in a worst case scenario, not the typical burn. Most residential creosote fires hit around 1,800 to 2,000 degrees at the peak, but a more common sustained burn in a stainless liner is closer to 1,600 to 1,800. I've seen a few thermal imaging tests from UL that put the average chimney fire temperature right around 1,700 degrees for most installations. Still plenty hot enough to wreck your day, but that 2,000 degree mark is pretty extreme and usually only happens with heavy deposits or certain fire conditions.

angelamurphy5d ago

People keep arguing over 300 degrees like it's some big gotcha but come on. A fire hot enough to melt aluminum is still a fire hot enough to ruin your whole setup. I seen a chimney fire in a neighbor's house back in '09 and the liner looked like a cheap soda can left in a campfire. Nobody stood around asking if it was 1,700 or 2,000 while the roof was smoking. The real point is if you're having this debate you probably already got a problem building up in your flue. Sweep your chimney regularly and you won't have to care what exact temperature your house fire was.

black.oliver5d ago

Huh, I gotta say I'm not fully buying that the difference between 1,700 and 2,000 really matters that much for the average homeowner. In my mind, you're still looking at a fire that's hot enough to melt aluminum, warp steel, and probably crack your flue tiles before you even notice. I've read some old case studies from the 80s where a "low temperature" chimney fire still caused 15 grand in damage because the creosote just kept burning and the heat transferred to the roof joists. So maybe the exact temp is off by 300 degrees, but the end result is the same - you're replacing your chimney liner and maybe a section of your roof. Isn't that basically splitting hairs when the whole thing is a disaster either way?