What are the real dangers of burning green/wet firewood? I had a good hot bed of coals going in my wood stove, and I stuck in what turned out to be a couple of green chunks of wood (was not intentional). They quickly burst into flame and burned fairly well, though a bit slower then the dry stuff. Are there conditions, such as a hot established fire, where you can burn green/wet wood, if it burns quickly and well?
Smoldering fires generate more creosote:
Wet or unseasoned wood greatly increases the accumulation of creosote. The large amount of moisture from burning wet wood condenses in the chimney and adds to creosote formation as well as the acrid odor. The periodic use of a good liquid or powder chimney cleaner which is sprayed on the burning wood is essential to the wood burner. This type of product will not elminiate the need to clean your chimney or the formation of creosote, but it will make the cleaning task much easier.
Creosote - Creosote can be defined as a combustible deposit in the venting system which begins as condensed wood smoke including tar fogs and vapors. Creosote is a by-product of incomplete combustion. If a fuel is fully burned there will be no smoke and, therefore, no creosote. Creosote will be hard brown or black and form either curly, flaky deposits or bubbly deposits in the venting system. Creosote is flammable.
The reply is quoted from both
Creosote is flammable.
As anyone who has ever had a chimney fire will attest to ;>)
Modern building codes for woodstove steel chimneys require that they withstand temperatures of 2000 Fahr. Normal burning is in the range 200-500 and creosote fires in chimneys commonly exceed 1000 Fahr. If you are sure your chimney is OK, some firemen recommend a chimney fire as the fastest way to clean it. The sound is terrifying but seldom lasts more than 10 minutes. The main danger is more probably sparks on the roof than overheating interior structures -- but only if you are sure your chimney is in good condition, double-walled, etc.
We had two such fires in 12 years and this is what the firemen told us. They did not mind being called out although both times they arrived long after the chimney fire had exhausted itself.
Laughing ... that's pretty much what I experienced ... saw it myself ... it was like 4th of July above my roof. The roaring sound tipped me off, so I went outside to look. Luckily, it was raining that night so I didn't need to worry about secondary fires.
The bad news was that my ceramic flu liner cracked :>(
Some firemen recommend a chimney fire to clean it? I don't think that's a good idea.
The wet wood takes a lot of the energy of the fire to evaporate the water in the wood before it will burn. The result is much less heat from burning it. Let it dry first. As others said, creosote problems will be higher also.
Bob
If you *DO* have a chimney fire, you shouldn't burn in that stove/fireplace again until someone inspects the chimney.
And no, you shouldn't ever start a chimney fire on purpose.
Are you the mean man who burned Santa a couple years back? You should be ashamed.
I've heard different ways to extinguish chimney fires. Dry chem powder extinguishers seem to be the most reccomended. Leaves an incredible mess, though. Better than losing the entire house.
I've wondered if a water mist (garden sprayer) would fill the chimney with steam, while not severely cooling the chimney.
How would you start one? Not that I want to know how to start one, but rather how to avoid starting one. When I startup my stove, there are some good flames entering the chimney from the stove until I get the fire going and close the air intakes down.
You can start a chimney fire, if there is a coating of creosote to support it. If you want to find out, load your stove with hot burning stuff and give it all the air that you can (not recommended).
It is an urban myth ... start a chimney fire once a year as a self-cleaning method. Not recommended!
Chimney fires can start secondary fires and damage chimneys.
LOL, I wasn't considering starting one. I was just wondering when it is more likely to happen, and if there is anything that can be done to prevent it other then periodic cleaning and don't over fire the stove.
Over firing can certainly start one, but a hot fire can prevent a chimney fire. The hotter the interior of the chimney, the less likely the creosote is to condense on the sides of it. Twice a day I'd crank up the stove to help keep it clean. In mild weather, the stove may tend to burn very slow and that is when you get the buildup. Then the weather turns cold, you crank up the fire and too hot can ignite what is already in the liner. Avoid smoldering fires, especially with green wood.
You avoid starting one by inspecting your chimney at the beginning of each season, and cleaning it when you start seeing a buildup of creasote. If you you burn wet or otherwise crappy wood, or indulge in short burns or banked fires, then inspect it once a month, until you get a feel for how fast it builds up crap.
If you WANT to destroy your chimney and burn your house down, then use your stove as a smudge-pot.. fill it with big chunks of wet, resinous pine, and keep it just barely burning for about an hour a day for two months. THen fill it with dry birch splints and kindling and light the sucker off.
It's probably a misapprehension of the advice to burn long hot fires, to warm the chimney enough to keep creasote from condensing there.
I dunno why you'd wanna do that, though, when you can scrape it off with a wire brush and use it to treat your fence posts when nobody's looking.
OK, here is another question. My chimney goes up about 6-7', and then bends. Last year I had it inspected, and they inspected up to the bend only and said that buildups only happen in the first 6 feet or so. Is this true? How far up the chimney do I need to clean, how far up is creosote likely to build up? I have a steel double layer 6" (I think it's 6") chimney.
Buildup of creasote is only one of the things they ought to be looking for. THey should also be looking for damage, blockages, problems with the roof penetration, etc. If there was no sign of creasote in the part you can see I wouldn't worry much about it for this year, but I'd definately choose a different person/company for next year. Can *YOU* get up on the roof and check it from the top?
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