Creosote Formation From Pellets?

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WNYRob
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Post Tue. Dec. 04, 2012 8:27 pm

I was just wondering if anyone burning wood pellets ever had creosote formation in their flue pipe. I have some dripping down the outside of my flue. I am assuming it is dripping off the chimney cap and running down the side through the support box, into the room (if rain is blowing the right way we get small drips of water running down the outside of our flue also).

I am kind of surprised at this since I always assumed pellets burned very cleanly. The only reasons I can think of is that 1)sometimes I burn my stove at low temps just to give our main coal furnace a helping hand in the real cold weather or 2) I got a hold of some cheap pellets. I try to buy just hardwood and stay away from the cheaper ones from Lowes or Tractor Supply which sometimes have pine mixed in.

Anyways, just wondering if anyone else had any experience with this. Thanks.

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SMITTY
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Post Tue. Dec. 04, 2012 8:29 pm

ANY wood produces creosote. I know that from experience. Even burning 20 year old, bone dry OSB will produce it ... and ALOT of it.

The good news is, a nice coal fire will clean that right out of there for you. :D ;)

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Lightning
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Post Tue. Dec. 04, 2012 9:33 pm

Hmmm, I have a pellet stove insert. A few years ago, I experimented with trying to make it more efficient so I cemented off some of the holes in the burn pot up around the top and outside edges. My logic was to only let in air that would be burning the pellets, instead of some of that air just carrying heat out with it.

Well guess what.. IN doing so, I starved the combustion process and creosote built up in the cavities behind the stove and in the flex pipe, it would occasionally ignite and the backside of the insert would get dangerously hot to the point that smoke was rolling out from behind it and I nearly melted wiring and motors and whatever else is back there :shock:

Yeah, won't do that again :lol: So yeah, wood pellets can definitely produce creosote under the right conditions :oops:

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Post Tue. Dec. 04, 2012 10:26 pm

Lightning wrote:Hmmm, I have a pellet stove insert. A few years ago, I experimented with trying to make it more efficient so I cemented off some of the holes in the burn pot up around the top and outside edges. My logic was to only let in air that would be burning the pellets, instead of some of that air just carrying heat out with it.

Well guess what.. IN doing so, I starved the combustion process and creosote built up in the cavities behind the stove and in the flex pipe, it would occasionally ignite and the backside of the insert would get dangerously hot to the point that smoke was rolling out from behind it and I nearly melted wiring and motors and whatever else is back there :shock:

Yeah, won't do that again :lol: So yeah, wood pellets can definitely produce creosote under the right conditions :oops:
It is still just firewood, just smaller. The misconception that it is cleaner than coal, comes from the marketing.
Last edited by Flyer5 on Wed. Dec. 05, 2012 2:50 pm, edited 1 time in total.

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rockwood
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Post Tue. Dec. 04, 2012 11:36 pm

WNYRob wrote: I got a hold of some cheap pellets.
WNYRob wrote:sometimes I burn my stove at low temps
Could be a combination of both but I would check to see if it's building up in the pipe or just at the cap where the creosote is more likely to condense.
I had a pellet stove in the early 90's and when I would run it at a low setting, I would have to clean the creosote out of the stove more often than when I ran it on medium/high.


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Rob R.
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Post Wed. Dec. 05, 2012 8:26 am

Just up the road from me there are two houses with pellet stoves vented through the wall. By last spring I was shocked at the amount of black soot on the siding. The summer rains got most of it off, but now it has started again. :roll:

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Post Sat. Dec. 08, 2012 8:55 am

A friend of mine who happens to be a fireman, told me he had a raging chimney fire using a P38 pellet stove. I was a little shocked as I had been told pellet stoves don't produce creosote. :shock:

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McGiever
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Post Sat. Dec. 08, 2012 7:17 pm

Creosote is fuel also...if you don't have the correct air to fuel ratio, well it goes up and out the flue, where along the way it can condense if cooled enough.
Same goes for soot, it is unburnt fuel...match the air and all is good. In reality, it is easier said than done, it is usually a compromise...sort of a middle of the road adjustment, due to ever changing heat requirements of the appliance.

BTW...Tractor Supply, here locally, has some darn good hardwood pellets.
also Big box stores pellet brands seem to change from year to year and even region to region. YMMV :)

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Post Tue. Dec. 11, 2012 5:43 am

I noticed the mess coming out of pellet stoves as well. Sometimes it is black soot, and other times it is this yellowish ooze that I would not want on the side of my house, especially in the amounts I have seen. That is why I laugh when people hear that I burn coal and say, "well, yes the price is good, but what about the mess", my question is, "what mess?" I burn wood here as well and the wood is 10 times the mess compared to coal.

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Post Fri. Jan. 04, 2013 10:50 am

They can get creosote but they're not supposed to under normal working conditions. I'm thinking it would take a lot of stove abuse, bad pellets, bad seals/gaskets, or a bad install for that to happen. My stove gets black soot easily but it's also badly in need of a leaf blower treatment. It's never had creosote though. For anyone who has those problems, I'd say check all seals and deep clean the stove (brush every little nook & cranny, get behind the firebox if possible, remove the fans & clean them, brush the vent pipe then stick a leaf blower on it to suck all the remaining ash out). As a last ditch effort try a higher quality pellet as some stoves are picky about what they will burn. And yeah, pellet stoves are messy and need a LOT of cleaning. If they're not deep cleaned about every ton, black ash on the outside of a house and occasional fires are the result.


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dcrane
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Post Fri. Jan. 04, 2013 12:12 pm

SMITTY wrote:ANY wood produces creosote. I know that from experience. Even burning 20 year old, bone dry OSB will produce it ... and ALOT of it.

The good news is, a nice coal fire will clean that right out of there for you. :D ;)
great post smitty and all so true! made me laugh too! :D

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009to090
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Post Fri. Jan. 04, 2013 1:35 pm

Yep, usually the pellets absorbed a little water if your getting ALOT of creosote..

Or, you are constantly burning the Pellet stove at a low setting, which deprives the conbustion cycle of O2, thus creating nasty byproducts (creosote & soot).

I have a small pellet insert that'll burn from 1,000 BTUs to 25,200 BTUs. I never run it less than halfway, about 12,500 BTUs. That way, the only byproduct, is a fluffy brown ash, similar to coal fly ash. VERY easy to clean up, I just vacuum it all out with my Ash-Vac.

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grumpy
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Post Fri. Jan. 04, 2013 2:10 pm

The good news is, a nice coal fire will clean that right out of there for you. :D ;)
Does that happen in say a day, or a week of burning coal?

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Cyber36
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Post Mon. Jan. 14, 2013 1:42 pm

grumpy wrote:
The good news is, a nice coal fire will clean that right out of there for you. :D ;)
Does that happen in say a day, or a week of burning coal?
Longer than a day, shorter than a week........

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