Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: lakotazz on January 19, 2011, 12:02:53 PM
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Hello all. This forum has been a great resource for me, and after ~4 years I am finally having a problem with my Aqua-Therm 275:
My wood boiler is in my garage; it has a 20-ft long, insulated stainless steel chimney. A few days ago I cleaned it with a chimney brush as I do every few weeks throughout the winter. This seems to get the chimney very clean, but there is always a very thin sheen of the hard, shiny black stuff left on the inner wall - it has always been there and it seems impossible to get rid of it all. A few days after cleaning I had a chimney fire. It started after refilling with wood - that point when the large, hot flare-up begins with the door open. It was scary but burned itself out after ~15 minutes (I blocked the chimney at the bottom).
The next day I opened the chimney and re-cleaned it - almost nothing came out. I've never had a chimney fire before I assumed because I was doing a good job cleaning it. Then, a couple of days later the same thing happened - whatever creosote left in the chimney ignited. Again it seemed like embers or flames from the initial "hot" fire made their way into the chimney, around the plate at the top of the firebox.
FYI, I burn only white birch (with the papery bark) which flares up quite a bit at the beginning. Any thoughts on ways to avoid these chimney fires would be welcome.
Best - Euan.
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is this wood your burning greener than normal? if your getting more creosote your more likely to have a chimney fire.
If it was outsdie a chimney fire every now and then would be a good thing
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I forgot to mention that... all the wood I'm burning has seasoned for ~1.5 years. It's unsplit, bark on. It seems well seasoned to me.
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yea it should be............. i know of no logical reason that it would flare up now more than the past
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This is why I refuse to install into a building. With a short stack you never have to worry about a chimney fire.
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mine is in a building but the chimney is allready 5 feet as it leaves the OWB so the total length is only about 12 feet. in (this being the 11th wnter) all my years with this stove i can honestly say i have never cleaned the chimney. i take a look up teh stack with a mirror now and tehn and if it looks like there are some buildup on teh side i jsut elave the door open for 5 minutes and let it burn. my chimney is 1/4 inch thick 8 inch steel pipe and insulated with 1200 degree insulation i obtained from and industrial site. i had a fire placw with that so called great snap together insulated chimney pipe. after five years i took it out of operation and when i pulled my chimney apart the bottom section (i would guess the hottest) had holes the size of dimes in it and the insulation was coming out! I would not recoment that to anyone, especially an OWB owner
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Thanks for the replies. I have pretty close neighbors so I need to have a pretty tall stack in any case. And yes, I have a chimney made of the snap-together insulated kind. During the first chimney fire, on the sections above the roof, I could see the clamps at the seams turning red hot. The roof is covered in snow so I wasn't worried about anything catching, but still not good in terms of degrading the chimney, I'm sure.
Every day or two I let the fire burn furiously with the door open for a few minutes, presumably to burn off creosote. Perhaps I'm not doing this long enough, or wrong. I'm not sure what qualifies as a "hot fire" but this sure seems to be. I can clearly see that some flames make their way into the chimney, which is what caused the creosote to ignite recently.
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The answer to your problem may be to find a way for your furnace to burn cleaner. This would allow the creosote to burn up before entering the chimney. I have had costumers who have had similar problems and we solved it by installing a larger draft fan to force more air on the fire and resulting in a cleaner burn.
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Aqua-therm 275 user here to.. ( 4th yr as well) My stack and pipe is the same height as yours.. Mine is not in a building..Ive had stack fires in the past...Try using Ash-thol..Its sopose to make the soot non flamable..I use it esp in the spring where it doesnt run as much...
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my neighbor burns pop cans in his stove all the time.. he said ever since he started burning pop cans he hasn't had a flu fire.
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Can you elaborate on "ash-thol"? I'm not finding anything about it.
And, um... pop cans??? Maybe that's an inside joke - I'm not getting it :)... Unfortunately anything like that has the potential to jam my ash auger, so I probably won't try that.
Indeed I might need to amp up my fan to burn hotter and cleaner. Thanks for the feedback.
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Can you elaborate on "ash-thol"? I'm not finding anything about it.
And, um... pop cans??? Maybe that's an inside joke - I'm not getting it :)... Unfortunately anything like that has the potential to jam my ash auger, so I probably won't try that.
Indeed I might need to amp up my fan to burn hotter and cleaner. Thanks for the feedback.
that wasn't a joke. They won't jam anything either, they burn up completely from what I've seen. At least I don't see pieces of can in his ashes. He says that it does something to the creosote or somethig, he rattle off the science behind it but I wasn't listening well
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What temperature range are you operating your stove at? I know my stove produces more creosote in the summer when I have it set lower. Maybe a higher temp setting will help keep the flue gasses hot enough to keep the creosote formation down.
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hello lakotazz
i sent you a personal message could you reply please
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TSP (Tri Sodium Phosphate) is the active ingredient in most creosote removers sold for indoor stoves. Used this stuff for years. Works good. I have recently heard that soda ash works well and is the ingredient in ash trol.
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I have the low/high set at 120/160 deg F. Anything higher and I get the occasional overheating problems. As far as temps in the firebox, they fluctuate from extremely hot (every time I load it) to mostly smoldering during the day. I don't use it in the summer so I never get long periods of smoldering.
I've always figured additions to deal with creosote were good for fireplaces that are used now and then, but generally couldn't do much with the volume I burn in my boiler. I think that's what the local stove guy told me - bad information?
FYI - I haven't had a chimney fire since my first post, but I'll keep you updated.
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The 120 in 120/160 is awful low. If your boiler temp is at 120 than you can bet the flue gas is even lower which combined with other factors like wood species and moisture content is a recipe for big time creosote formation. Good luck.