Sparky woodstove
February 3, 2011 7:48 AM   Subscribe

Strange woodstove question: Occasionally, there's a little shower of sparks that flies off the back surface of the stove. What's going on?

I have an older Lange woodstove just like this one, except with flat black surface rather than enamel. It is in its second season in my house, but was bought used and fully rebuilt from a professional rebuilder. Chimney sweep came last fall and pronounced it in good shape and correctly installed. I've burned about 1.3 cords since that chimney cleaning, all well-seasoned hardwood.

Lately, every few days I have noticed a little shower of sparks that emanates from the back curved surface of the stove, which faces a brick wall and the stove sits on a fireproof pad, so the sparks dissipate harmlessly. The stovepipe is tight and I can see no cracks or holes anywhere. The sparks are like what you might get from a sparkler, they're not big flying embers; the whole thing is like a two-second burst at a rate that's maybe 20% of a typical sparkler output. I spend a lot of time in the room with the stove and have noticed this about 3 times in 10 days.

The stove is not particularly hot when this happens — stovepipe temperature gauge showed only 250 degrees 3 feet above the stove during the last instance. Usually we burn it a bit hotter than that. I did not notice this happening at all during the previous winter of use.

Anyone ever experience this? Any theories? Could it be just bits of paint on the surface that are reacting somehow?
posted by beagle to Home & Garden (5 answers total) 1 user marked this as a favorite
Anything that happens to get on the back of your stove could easily burst into flame when the stove gets hot enough. For example, spiders like to find hidden places to lay their eggs, you find those in all sorts of odd locations. Heat them up and they burst into flame. But it could easily be something entirely different. Lots of things burn.
posted by grizzled at 8:47 AM on February 3, 2011

My first guess would be insect detritus, but I can't imagine that would cause such bright sparks.

Is it possible that something is falling of the wall and collecting on the back of the stove? Or perhaps from the joint between the ceiling and the wall?

You haven't been filing metal or something like that in the area recently, so fine powder could be left in a niche somewhere and occasionally fall onto the stove by random vibrations?

I'd make sure that nothing could catch fire if this were to start happening on a different part of the stove.
posted by HFSH at 8:51 AM on February 3, 2011

I've had that happen with dust bunnies, cobwebs, pet hair, that kind of thing. Stuff like this does make a "sparkler" sort of sound when it comes into contact with the outside of the stove.

Try sweeping up (and possibly mopping) the floor below your wood stove, and the immediate surroundings. As the stove heats up, you get an up-draft, which sometimes tends to suck stuff towards it from the immediate surroundings.
posted by ErikaB at 10:13 AM on February 3, 2011

Next time your stove is cool, feel around the back for any soot or charred stuff. Also feel for any cracks. That would make me nervous. I have not seen anything like that happening on my wood stove.
posted by DarkForest at 3:11 PM on February 3, 2011

My guess is that a small cloud of fine carbon particle-rich gas is escaping from the exhaust stream coming out of the stove (probably out of the stovepipe) and that the particles of carbon are igniting and showing up as sparks when they hit the hot back of the stove (or perhaps merely when they hit the higher oxygen content of outside air).

The fact that the stove is relatively cool would account for the fine particles of unburned carbon I am hypothesizing.

A year of heating and cooling cycles might suffice to make the leak my theory requires.
posted by jamjam at 1:40 AM on February 28, 2011

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