Do You Think This Pellet Stove Creosote Buildup is Dangerous or Normal?

[DarbyDog]

I'm new to pellet stoves. Have had an old Whitfield Quest pellet stove in my basement for over fifteen years--came with purchase of the house. But i only started using it last winter and I don't know the history of how much use it had prior to that.

But anyway, my present concern with it is the creosote buildup in the exterior vent pipes that consist of about seven feet worth of pipe, all of which I have just began to attempt to clean.

I've attached a photo of the removable ash trap at the end of the exhaust pipe and the glazed, flat (maybe 1/16" thick) creosote in it; seems impossible to remove. The worst part is that this same hardened creosote is extensively present in all the vent pipes and seems resistant to any practical method of removal. I've tried a wire brush wheel attached to a power-drill extension rod and even oven cleaner. Nothing phases it except in a very minor way, with a small amount of black dust coming off.

Googling this issue yields a multitude of opinions.

But I'm actually now considering replacing all vent pipe given the potential danger involved.

Think I'm over-reacting or is replacement of all pipes the best option? Opinions?

 

[johneh]

creosote in a pellet stove is not normal. because of the way
you use your stove that may not even be creosote maybe ash
that has soaked up moisture and hardened. I take it that what
you are showing is the clean-out cap. Just a suggestion take it
outside fill it with newspaper and set it ablaze if you get very
black smoke and flame then it is creosote. If the paper just burns
normally it is not creosote

 

[Washed-Up]

What Johneh said…also if you take the pipe apart , spray the inside with a strong degreaser and let it sit for 20-30min then rinse it off with water. I’ll run my Harman P61A up at higher temp at least once a week during the winter…this gets rid of any creosote that may begin to form. Welcome to the form and pellet heat

 

[DarbyDog]

creosote in a pellet stove is not normal. because of the way
you use your stove that may not even be creosote maybe ash
that has soaked up moisture and hardened. I take it that what
you are showing is the clean-out cap. Just a suggestion take it
outside fill it with newspaper and set it ablaze if you get very
black smoke and flame then it is creosote. If the paper just burns
normally it is not creosote

Thanks. Okay, I'll try that and let you know.

What Johneh said…also if you take the pipe apart , spray the inside with a strong degreaser and let it sit for 20-30min then rinse it off with water. I’ll run my Harman P61A up at higher temp at least once a week during the winter…this gets rid of any creosote that may begin to form. Welcome to the form and pellet heat

Thanks. Okay, well I"ve already tried oven cleaner--no luck with that. What "strong degreaser" would you suggest? And yes--if i can get this stove into good enough working condition (I recently did the leaf-blower cleanout, etc.), I'll try the higher-temp routine. During my first seasonal run with it this past winter, though, I don't think it ever did get hot enough to burn anything off. I had to run it the whole time at the lowest pellet-feed setting with the damper wide open.

And taking the pipes apart is near-impossible. The only section of pipe I have been able to remove so far has been the two-foot section. The other pieces won't budge even a sixteenth of an inch.

 

[DarbyDog]

Johneh:

Well now...Isn't this interesting. A science experiment.

I tried the crumpled-paper test, The black residue did not catch fire with lighted paper. However, when I hit it with a propane torch, it glowed bright orange wherever I placed the point of the flame and then, after a few seconds, it burst into flame so forcefully that it blew out the propane flame. But then, when left to burn on its own, the flame rather quickly died out. I didn't notice any black smoke though.

So what do you make of that?

There has to be some combustible material in there, even if it's mixed in with old hardened ash, wouldn't you think? And wouldn't that combustible material have to be creosote?

 

[Washed-Up]

Whatever you can take off and spray will help. This is a product I use, and I mix it 50/50 or 4:1

 

[DarbyDog]

Whatever you can take off and spray will help. This is a product I use, and I mix it 50/50 or 4:1

View attachment 327924

Thanks, Man. Appreciate it.

Before getting this stuff or a product like it, though, I decided to give the oven cleaner another try. And Voila! It's working now. It hadn't been working the first time I tried it a week or so ago, but I'm sure that was because I had left it on too long, causing it to dry up. So this time I sealed this clean-out cap from air (a plastic lid) after spraying it heavily, waited about fifteen minutes, and wound up with exactly what I had wanted to see: a milky dissolving of the creosote which I was then able to wipe out with some old rags. It took three applications to get it to the photo you see attached here in 003, but this is now very encouraging in terms of prospects for getting all pipes cleaned out. And it's going to be especially helpful, I think, because of the ease of application--spraying the oven cleaner into the pipes and then sealing them from evaporation. It also seems really important to saturate the surface of the creosote. So I'm thinking I'll probably buy a couple of spray cans of it for that.

I think this is actually an important discussion. I am appreciative of the fact that there seem to be relatively few pellet stove chimney fires as compared to wood stove chimney fires, however...any of those fires is potentially life-changing and disastrous, not only from a financial standpoint but from the standpoint of loss of life. And in my case, living as I do in the middle of Rocky Mountain lodgepole pine forest, any such house fire could be disastrous for thousands of people from a forest fire.

Anyway, that's why I've been spending so much effort on trying to get this issue resolved and why I've been perhaps overdoing things.

I also am finding it really interesting that the hardened creosote I'm dealing with seems highly flammable at only very high temperatures (see my previous comments about it igniting with a blow-torch but not with crumpled paper). It makes me think that in any kind of chimney fire, perhaps this kind of thin lining of pipes with very hard creosote could be the nail in the coffin for chimney fires that start slowly but then explode out of control as the temperature gets high enough to ignite the thin layer of hardened stuff that chimney sweeps may very well be missing even with annual cleanings. Just conjecture on my part though--I'm certainly no expert.

Photo 001 shows the original hardened creosote even after trying to scrape with a screwdriver without anything at all coming off. Photo 2 shows second application of oven cleaner after only ten minutes. And photo 3 shows results after wiping out with cloth on the 3rd application.

The other reason I'm super-happy about this working is that 4" pellet stove vent pipe is currently incredibly expensive to replace. So my plan now is to saturate the heck out of all pipes, seal them from air and then, after fifteen minute intervals with three applications, attach cloth to my wire brush-wheel/power drill setup to get all/most of the stuff out of there.

Hope this helps others a little who may have the same issue.

Washed-Up: Once I get this all cleaned out, I'll try your liquid cleaner for yearly cleanouts. And probably for my glass door as well. Thanks again.

 

[Washed-Up]

Nicely done…also I’m in the Rockies surrounded by lodge pole pines, albeit the Canadian side…I’ve never had or seen an issue with creosote in my area, I also service most of the Pelletstoves in my immediate area…pipes all sprayed and hosed down in the spring…great diligence of your side! Happy burning

 

[johneh]

Johneh:

Well now...Isn't this interesting. A science experiment.

I tried the crumpled-paper test, The black residue did not catch fire with lighted paper. However, when I hit it with a propane torch, it glowed bright orange wherever I placed the point of the flame and then, after a few seconds, it burst into flame so forcefully that it blew out the propane flame. But then, when left to burn on its own, the flame rather quickly died out. I didn't notice any black smoke though.

So what do you make of that?

There has to be some combustible material in there, even if it's mixed in with old hardened ash, wouldn't you think? And wouldn't that combustible material have to be creosote?

Just shows how much heat it takes to get it to fire up

 

[shtrdave]

This is good information to have, all of these ways to deal with it.

I am curious, as the way my mind works, once I saw it flame away from igniting with the torch, I could have seen me laying the pipes out in and upward angle and igniting the bottom and allowing it to burn out. Was that a thought or is that no something you feel would have worked?

 

[johneh]

This is good information to have, all of these ways to deal with it.

I am curious, as the way my mind works, once I saw it flame away from igniting with the torch, I could have seen me laying the pipes out in and upward angle and igniting the bottom and allowing it to burn out. Was that a thought or is that no something you feel would have worked?

Twice a year the smoke pipe on my wood furnace is
removed taken outside and we do exactly what you
describe. The inside of the pipe looks brand new
when done and brushed

 

[DarbyDog]

This is good information to have, all of these ways to deal with it.

I am curious, as the way my mind works, once I saw it flame away from igniting with the torch, I could have seen me laying the pipes out in and upward angle and igniting the bottom and allowing it to burn out. Was that a thought or is that no something you feel would have worked?

Shtrdave,

That thought had occurred to me as well. However, that would have been experimenting with the unknown and I happen to live in a very dense, overgrown lodgepole pine forest in the Colorado Rockies. Risk of forest fire here is extremely high. Because I had seen the creosote explode, on a small scale at least, in my clean-out tray when I hit it with the torch, I didn't want to risk doing that in the larger pipes, especially not knowing how much creosote was inside.

I don't know for sure what would have happened if I had attempted to accelerate fires inside the pipes or even if I would have been successful at burning it all out; had to err on the side of caution by not attempting it. I had also thought about trying something like paint thinner or even gasoline as a chemical way of dissolving it, but since Easy Off oven cleaner was working, I just settled for that. And I'd always want to avoid using gasoline or paint thinner for things like this anyway. I'm certainly not suggesting anybody try that; I'm no professional, just an average homeowner.

It's gratifying that somebody has found the info useful, though. And for anyone reading this thread in the future, let me suggest to you that you perform YEARLY clean-outs of vent piping before creosote builds up into a rock-hard layer like mine did. One of the Canadian posters here, WashedUp, apparently runs a business in which he does yearly clean-outs for customers using a strong degreaser. That's what i'm going to be trying in the future on my own because I think neglecting to keep up with removing that buildup of softer creosote year after year eventually leads to the kind of issue I had to deal with of a thick layer of very hardened material. Nothing was dissolving it except for oven cleaner. And it's a LOT of work to get it removed, even with oven cleaner. In addition, this creosote will cement your vent-pipe sections together, making cleaning all the more difficult if not impossible. I was only able to disconnect one out of about six pipes and elbows, with no way of getting oven cleaner to work its way into the other fittings. In fact, I damaged a whole section of elbows trying to get them separated.

DO YEARLY MAINTENANCE!

 

[stoveliker]

A few thoughts (I've followed this thread as I found it interesting, and I think it's not limited to pellet stoves; I am a cord wood burner, so take what I say with a grain of non-pellet salt).
:
- would having a fine (insect?) mesh on the end of the pipe be sufficient to avoid embers coming out (so you can burn it out)?
Cleaning though is always safer indeed.

- I am not sure that creosote like that hardens *over time* as you seem to imply. Different creosote types are the result of different types of (improper?) burning. One can get a hard layer of creosote in one day of something going wrong. At least, that's how it goes in cord-wood land.

Thanks for documenting an interesting journey. I learned something.

 

[DarbyDog]

Sure--I agree. It's all a best guess on my part as to what's going on. I'm frankly astonished at what appears to be a lack of in-depth research by scientists on the dynamics of such a potentially deadly substance as creosote that you would think would show up on the Internet. I didn't find any such research. My "over time" comment, although conjecture on my part, was based on the little experiment I did with the creosote I had in the clean-out cap which was a very representative sample of the buildup I found in all the piping I wound up having to clean out. And none of these pipes had been cleaned or even examined for at least six years. And even though I had never run the stove for more than three or four times per year during that period. I was envisioning some layers of creosote having built up and become harder and harder over that period with each successive year. And, yes, even last winter's layer was very hard; It would even scrape off with heavy pressure from a screwdriver. But I think when I layed the tip of the propane torch flame on the creosote for about five seconds and then it suddenly "exploded," with a rather brief flame (three or four seconds), it led me to suspect that I had broken through a top layer (from last year's and recent years' burns) and into perhaps some even more hardened-over-time and difficult-to-ignite layers from previous years. And if research showed that to be the case, that the extremely hardened variety of creosote was kind of a silent time bomb, I would think that quite an important finding.

But I'm certainly no scientist when it comes to fire--not in the least. But I would be interested to know what some of you ministers of fire might conclude by doing similar experiments.

As far as using fine mesh for burning out the pipes, my first thought is that anything that fine would probably get quickly melted out. But in any case, given the placement of my house in the middle of a dense pine forest, I would personally never risk starting a forest fire by trying that. That's another experiment I'd have to turn over to people like yourselves.

Thanks for the interest.

 

[stoveliker]

I understand.
My experiment is different: try to avoid creosote at all costs
So far so good...

 

[johneh]

As far as using fine mesh for burning out the pipes, my first thought is that anything that fine would probably get quickly melted out. But in any case, given the placement of my house in the middle of a dense pine forest, I would personally never risk starting a forest fire by trying that. That's another experiment I'd have to turn over to people like yourselves.

One thing to realise is that when I burn out my pipes it is in the winter with
a thick layer of ice and snow on the ground so the hay field next to the house
is covered in snow, no chance of a wildfire That's why it is called the Great White North