single-wall stove pipe collecting debris

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RustyShackleford

Minister of Fire
Jan 6, 2009
1,344
NC
My BK Princess is connected to the double-wall metalbestos chimney with 5ft or so of single-wall stovepipe; a bit more than halfway up, there is an offset of about 12" accomplished with two 30-degree elbows (so there is 24" of pipe coming straight up from the flue collar).

I'm having a problem with dry flakey debris forming on the inside of the stovepipe. I can literally hear it periodically falling down into the stove. After half a season or so of burning, there's enough of it that it interferes with the operation of the bypass damper - and I need to remove the pipe and clean it and the stove out.

I am bewildered as to why this is happening. When I remove the stovepipe, the chimney-proper (the double-wall metalbestos) is reasonably clean. I've had the stove for over 10 years. I don't recall it happening during the first years of using the stove, in fact it's only been the last few years. The only thing that has changed is that i installed a new chimney cap, one that has a screen, and inserts inside the top of the chimney. I do regularly turn the stove down very low when I go to bed, but the catalytic converter is still active in the morning (temperature well over 500 degrees). My firewood is very high quality, mostly oak aged for at least 2 years under shelter.

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I suppose it could be causing a poorer draft, but I haven't really noticed that otherwise - stove performance is fine, and I have to be a little careful about smoking when re-fueling, but again, no change.

Maybe I simply need to move to double-wall stovepipe - which is, in fact, what Blaze King recommends, though they've also agreed that single-wall may be workable, if my chimney draft is good enough and I'm careful when opening the door (don't jerk it open).

Maybe I should re-install the old chimney cap, but I find it really implausible that it's the culprit.

Thoughts ?
 
Sounds perfectly normal to me. When is the last time you changed the cat?
 
Normal ? Never had this occur with my Dutchwest (do NOT get me wrong, the BK is utterly superior), and this wasn't happening nearly as badly when I first had the BK.

Changed cat eight seasons ago. But I believe it's still working fine - I wake up in the morning and there's no discernible fire in the firebox and the cat thermometer reads well over 500 degrees.
 
Normal ? Never had this occur with my Dutchwest (do NOT get me wrong, the BK is utterly superior), and this wasn't happening nearly as badly when I first had the BK.

Changed cat eight seasons ago. But I believe it's still working fine - I wake up in the morning and there's no discernible fire in the firebox and the cat thermometer reads well over 500 degrees.
Yes, normal. Especially with single wall pipe. I can’t explain why you haven’t experienced this before now. I would consider a new cat before I’d blame the chimney cap. 8 years is asking a lot out of a cat.
 
I use single wall stove pipe with my Princess. There is usually more creosote build up in the stove pipe versus the triple wall chimney.

I run the stove a low a lot in the shoulder seasons. I’m sure that doesn’t help.

I don’t have issues with chunks falling from the pipe down into the stove though.
 
Normal ? Never had this occur with my Dutchwest (do NOT get me wrong, the BK is utterly superior), and this wasn't happening nearly as badly when I first had the BK.

Changed cat eight seasons ago. But I believe it's still working fine - I wake up in the morning and there's no discernible fire in the firebox and the cat thermometer reads well over 500 degrees.
8 seasons at 1000 hours a season you are in the window for a new cat. Unless you use it less than that.
 
My SW would do that, I would clap my hands on it and listen to the debris fall off into the stove.
 
My dad beats his single wall stove pipe every time he loads the stove. Beats it with a fireplace poker…. His stove pipe looks terrible ;lol
 
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8 seasons at 1000 hours a season you are in the window for a new cat. Unless you use it less than that.
Correct me if I'm wrong, but if I turn the stove down low (for the night, for example) and there's no discernible flame in the firebox, and yet the cat is reading 1000 degrees, doesn't that mean the cat is working fine ?

OTOH, I guess I could install a new cat, and if that doesn't help, put the old one back in and save the new one for later.
 
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I'll join the fray... There are plenty of cats still working after 8 years Rusty. Are they working as well as new, nope. But they can still provide very clean emissions with little to no opacity.

However, just because you wake up in the a.m. and the cat is active does not mean it was active all night. Is it possible for the cat to go inactive in the evening, and then recover during the night, yes. How does that happen? You load the stove at 8:55 p.m., shut it down and go to bed. For the first hour the combustion moisture can quench the cat. Is this common, nope. It can happen and on older cats it may happen more easily.

We suggest you load at 8:00 p.m. and run it at a bit of a higher burn rate to deal with combustion moisture. (Yes this varies depending upon how much MC is in the fuel load). Then at 8:30 close it down a bit and at 8:45 close it down a bit more and at 9:00, put it the cruise mode.

Your idea of getting a new combustor and cleaning your, wrapping it with gasket and keeping it on the shelf is a great idea.

BKVP
 
Thanks for chiming in, Chris ...

I believe my routine is more like your recommendation. I typically load the stove several hours before I go to bed, and gradually turn it down until I go to bed. I don't believe it goes inactive during that time. My firewood is quite dry, cured under shelter for a minimum of two years.

Your idea of getting a new combustor and cleaning your, wrapping it with gasket and keeping it on the shelf is a great idea.

You mean try a new one and see if it makes a difference, and then save it for later if it doesn't ?

Does this look like the excellent metal one that I believe you are now shipping with new stoves ? Good price too.

 
Thanks for chiming in, Chris ...

I believe my routine is more like your recommendation. I typically load the stove several hours before I go to bed, and gradually turn it down until I go to bed. I don't believe it goes inactive during that time. My firewood is quite dry, cured under shelter for a minimum of two years.



You mean try a new one and see if it makes a difference, and then save it for later if it doesn't ?

Does this look like the excellent metal one that I believe you are now shipping with new stoves ? Good price too.

What was in your stove new? Ceramic or metal substrate?

BKVP
 
If the cells of the cat look square, it's ceramic. If they are more rectangular, more likely metal. You can post an image if you like.

BKVP
 
My stove shipped with crappy "diesel foil" version, but upgraded to steel.

Go to the link I gave in post #11, then select "ceramic" and "metal" in the dropdown menu and you'll see the difference.
 
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I could also buy a new one, and if it does make a difference, do the acetic acid cleaning procedure on the old one.
 
Could it be that something moved a bit and you have an air leak there where you get the clumps of creosote?
 
8 seasons at 1000 hours a season you are in the window for a new cat. Unless you use it less than that.

1000 hours per year is only 6 weeks of burning. Something tells me that Rusty burns more than a lousy 6 weeks per year. If he burns 6 months per year which is way less than me then you're looking at 4320 hours per year.

Years of expected life has always been a ridiculous metric.

I propose we all ignore time references and just run it until it smokes on low. That’s how you know it’s shot, when the cat fails to clean up exhaust at low settings.
 
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My BK Princess is connected to the double-wall metalbestos chimney with 5ft or so of single-wall stovepipe; a bit more than halfway up, there is an offset of about 12" accomplished with two 30-degree elbows (so there is 24" of pipe coming straight up from the flue collar).

I'm having a problem with dry flakey debris forming on the inside of the stovepipe. I can literally hear it periodically falling down into the stove. After half a season or so of burning, there's enough of it that it interferes with the operation of the bypass damper - and I need to remove the pipe and clean it and the stove out.

I am bewildered as to why this is happening. When I remove the stovepipe, the chimney-proper (the double-wall metalbestos) is reasonably clean. I've had the stove for over 10 years. I don't recall it happening during the first years of using the stove, in fact it's only been the last few years. The only thing that has changed is that i installed a new chimney cap, one that has a screen, and inserts inside the top of the chimney. I do regularly turn the stove down very low when I go to bed, but the catalytic converter is still active in the morning (temperature well over 500 degrees). My firewood is very high quality, mostly oak aged for at least 2 years under shelter.

View attachment 322766


I suppose it could be causing a poorer draft, but I haven't really noticed that otherwise - stove performance is fine, and I have to be a little careful about smoking when re-fueling, but again, no change.

Maybe I simply need to move to double-wall stovepipe - which is, in fact, what Blaze King recommends, though they've also agreed that single-wall may be workable, if my chimney draft is good enough and I'm careful when opening the door (don't jerk it open).

Maybe I should re-install the old chimney cap, but I find it really implausible that it's the culprit.

Thoughts ?

Even with my double wall pipe, I regularly sweep the fallen debris from the bypass gasket with my hand. Like every time it's cool enough to do so. It can also be vacuumed out from below if you don't want to lift the stove pipe.

Lots of good reasons to go to double wall if you get the chance. Stainless steel should last forever. Tighter joints for stronger draft. Looks better. Safer. And of course insulated for better heat retention.

Lastly, even thought the cat is active your stove can be emitting very cold exhaust when run super low. So cold that it can easily condense in the flue and create creosote. When running low I purposely run the stove high enough that internal flue temperatures stay above 400 measured at 18" above the stove. You don't want those flue gasses condensing.
 
Yeah, 1000 hrs/year is way too low. But I keep coming back to the fact that the cat can easily be running at 1000 degrees with no visible fire in the firebox. How can it not be working ? But yes, I can believe the exhaust is pretty cold.
Lots of good reasons to go to double wall if you get the chance. Stainless steel should last forever. Tighter joints for stronger draft. Looks better. Safer. And of course insulated for better heat retention.
I'm a little intimidated about double-wall. How do I handle the dogleg in my pipe (the chimney is offset about 12" from the flue collar) ? Is there such a thing as adjustable elbows, or am I stuck with 45s (using 30s now, so gentler bends) ? How do you shorten a piece of it ?
 
Pull the trigger and buy a new cat, you’ll be very surprised at the increase performance / output of your stove once it’s running top notch again.