Travis Johnson wrote:
Roy Clarke wrote:I think wet wood is a bad idea. It will cool the gases (fuel) and send them up the flue as tar. The tar will condense until, one day you will have a chimney fire.
That is making the assumption that the homeowner does not brush out their chimney. I have never had chimney fire, but then again someone mentioning making sure to brush out their chimney once per year. I was rather shocked. I brush out my chimney once per MONTH in the heating season, sometimes every 2 weeks depending on what I am burning. (Right now I am burning green cedar because it has been fairly warm outside and I just need to take the chill off, so I brush about every 2 weeks.
But every time I build a chimney, I make sure it is very easy to clean out, because one that is easy to clean is one that gets cleaned. No creosote build up...no chimney fire.
I agree, wet wood is a VERY bad idea. I feel the same way about green wood.
If you have to 'brush out' your chimney multiple times during heating season, you are depositing a lot of creosote - hopefully, it's the chunky, brittle kind, not the sticky-tar kind.
Brushing won't do much to remove sticky creosote, until it gets hot enough to re-cook and/or burn.
And I definitely don't like the idea that some people "clean" their chimneys by having a chimney fire. (Nobody here has suggested this, but it's come up in other conversations with locals.)
Chimney fires suck.
As a volunteer
fire fighter, one of our worst fires last year was a couple who had just cleaned their chimney.
It caught on fire anyway - possibly some of the creosote got dislodged and settled down at the bottom closer to the heat, possibly some part of the chimney got bumped and ended up with inadequate clearance to the wall or ceiling combustibles, or maybe a piece was damaged enough that the cleaning broke a joint loose.
There was not much left of the chimney, or the wall for that matter, for us to find out more for sure.
Both occupants were on site, had time to move some belongings out of the farthest rooms of the house, but the room with the stove in it already had fire rolling across the ceiling, and the whole structure was a total loss.
He was trying to laugh it off with black humor, she was still shaking from hearing the cat dying in the attic.
We did what we could, with volunteers from the two closest fire districts, but it wasn't much we could do.
We had to finish the job with shovels and buckets of ice, as it was -10 F and the fire trucks were freezing faster than they could pump water.
That incident really stuck in my mind.
It was the 3rd or 4th chimney fire in 2 years, in a district with only a few hundred year-round residents. (It can be hard to tell a "woodstove fire" from a "chimney fire" if the residents weren't home when it started.)
1% per year does not seem like very good odds on chimney fires.
I now look at both visible smoke, and mid-winter chimney cleaning, as early warning signs of a possible, catastrophic, chimney fire.
It's not that cleaning it is a bad thing - it's a very good idea.
However, I can't forget the look on my neighbor's face saying "I just cleaned it" while his house is burning down.
If you know your stove produces creosote the way you run it, and you know this is a bad thing, then cleaning the chimney more often is basically a band-aid.
I do recommend hiring a trained chimney sweep in to inspect at least once, and show you what to look for. Some stoves are fine with once-a-year cleaning. Some stoves do build up fly ash faster. Peter van den Berg told me about inspecting a Swedish contraflow stove (masonry heater) he'd helped build 17 years prior, and finding out the owners had not cleaned it once in all that time.
If your inspection shows creosote- not just powdery soot and fly ash, but little crumbly chunks or drippy dribbles of creosote - then you are perpetuating a situation that could lead to a chimney fire sooner or later.
Creosote in any form is an early warning sign of a preventable emergency.
The fundamental problem that causes creosote buildup is running incomplete combustion, in a chimney cold enough to condense the creosote from the smoke.
Creosote is a very common thing for people to achieve as a side effect, when their goal is "keeping a wood stove going all night."
If your goal was "keeping the house warm all night," or even better "keeping my family warm all night," I have all manner of suggestions, from the frugal to the extravagant, no creosote required.
- masonry heating
- home energy audit / heat loss mitigation
- summer/winter heat design (beyond passive solar
- personal comforters
- personal heat reservoirs
- home heat storage reservoirs
- saunas, holiday foods, and other lifestyle tricks from the frozen North...
The other scenario that is even more horrifying are the folks who tell me, "oh yeah, we used to have a chimney fire 2 or 3 times a year, my dad would be up on the roof yelling at us what to do."
THIS IS HORRIFYING. Please never do this.
If your chimney is well-maintained and well-installed, your house might survive a chimney fire a lot longer than one that was installed wrong, or not maintained. But it's not the same as "safe."
Modern, manufactured chimney components are designed to take ONE chimney fire without failure, but repeated chimney fires will weaken the parts, loosen the joints, and degrade critical insulation and safety clearances.
I just moved a bunch of this post to a new topic, How Chimneys Work https://permies.com/t/72721/Chimneys-Work
, because it's not really on point for the original post on this thread
I do think that understanding how chimneys work is vital information to safely operate a woodstove, fire place, or any chimney-equipped heater.
If anyone is successfully keeping a wood stove going all night without causing creosote to build up in the chimney, I'd like to hear your methods.
- Is your wood stove the right tool for the job?
Most wood burning stoves, especially the cheap ones, are sold as "space heaters," not as a whole-house furnace or heater.
If you have reasons for wanting a light-weight woodstove (under 1 ton) instead of a bigger wood-fired furnace or masonry heater, and you want overnight heat from it, check the specs.
Look for wood stoves that have been tested and rated for a nice long burn.
Full-sized fire brick liners, or soapstone tile, or heavy iron bodywork might be good indicators of a sturdy stove, built to heat not just for looks. But the real deal-maker would be the number of hours it's rated to sustain its long burn, when it was certification tested.
Don't be too quick to dismiss masonry heaters for cost or size. A tiny masonry heater can hold heat all night, and you don't have to keep it burning all night.
Donkey's latest has a lot of charm: https://permies.com/t/71576/tiny-house-rocket-mass-heater
We slept with it for the first week or two after it was built; we'd fire it 4 to 6 hours and then have to stop, and it held the room above 65 for at least 12 hours afterwards.
How much wood could you save if you only had to run the stove half as long/half as often?
A savings of 6+ cords per winter could be $900+ in your pocket each year, or 50+ hours of work you don't have to do between day jobs to prepare for winter.
What is a good stove worth to you?
But this is not a thread about switching to a different stove or heater, sorry.
Do check the specs on your stove, however. Not all stoves are built equal.
If your model is just not designed for overnight heat, you may want to upgrade, or consider using the backup heater for night times if you have one.
Not all solid fuels are the same.
Some wood stoves are dual-purpose by design; others are not intended for coal (or any other fuels). A very different/wrong fuel could cause warping, chimney damage, or problems with CO and draft.
Coal takes more air to burn clean than wood, and can put off a different set of gases. Dirty coal (the kind with sulfur) was discovered to have weird effects on some types of mortar/chimney cements. I've seen photos of older masonry chimneys bending to one side, due to which part got more exposure to the sulfur/acid in the prevailing wind.
If your stove is not designed for burning coal, you might still be able to use wood charcoal for a cleaner burn.
(There are bigger versions of the TLUD that produce charcoal while you cook on wood gas
Charcoal seems like a safer alternative to using green or wet wood as the last load of the night.
Charcoal can still burn dirty, with CO and organic acids in the exhaust, but you should get less of the really nasty, sticky, sappy volatiles that contribute to the worst creosote problems.
The whole question of what to burn, unattended, while your family sleeps - I have to admit it kind of gives me the willies.
Having experienced thermal-mass heat, and passive solar
heating, I don't think I will go back. I've camped in the snow with a good foam mat and a sleeping bag.
I don't really like the idea of any fire burning unattended while I sleep. It even makes me nervous leaving electric cookers or pipe heaters on unattended. (Rodent+wiring is another fire scenario I've seen and would rather not see again).
I can admire the art
of keeping coals alive from the fairy-tale days, of big Russian ovens big enough to shove a witch into, and new fires once a year at Easter.
But I am happy to live in a part of history where both masonry and matches are cheap.
So I will leave the rest of this thread to others with more relevant experience.