Help troubleshooting weird creosote problem?

[coaly]

I can't answer why moisture would leak out the seams either, but there should be no moisture in there to leak.......

Any leaks around door or the closed off vent on rear leak air INTO the stove when chimney is warm. Not smoke out. The warm chimney has rising gasses that cause a lower pressure area in flue, pipe, and chimney allowing the higher atmospheric pressure in the house to leak IN. This would allow the fire to burn with intake dampers closed. (that's actually the patented name of them when Bob Fisher's father, Baxter invented them. So your terminology calling them dampers is correct.) Any leaks into chimney or pipe allows cooler indoor air to leak in, cooling the inner flue, causing the condensing issue you have as well.

6 inches above stove is not a good indication of pipe temp. Stove heat will affect the bimetallic spring that senses pipe temperature. Try it at least one pipe section above stove, then compare to the temp of the pipe just before it dumps into chimney. That will show you temperature drop at the top of connector pipe. Double that reading will be the internal gas temp entering chimney. Then you can estimate how much loss you have to the top. Not much with one section of chimney. If you can get a temp reading inside flue near the top, you can correlate 250* at the top to your inside measurements.
Double wall pipe inside will help tremendously.

Split everything but the smallest pieces.
As bholler mentions, rounds simply do not dry. Drying time starts when split, not cut.

 

[firekindler]

What moisture content is the inside of that unsplit price at? My guess is it is nowhere near as dry as it should be and when you shut your draft caps down that far you cause massive creosote problems.

Thanks, bholler - I don't have a moisture meter so I can't give you an empirical answer to that. However, most of those bigger unsplit pieces season in full sun (check my avatar picture) and not many clouds here for a good six months), off the ground on pallets, for at least two summers. Many of them are cut during the dormant season (I cut all my own wood), which really enhances seasoning. The fact that they burn well enough through the night with the intake draft knobs shut tight makes me think they are sufficiently seasoned. And in my second reply to coaly, you'll see that my only creosote problems are the leakage.

 

[firekindler]

I can't answer why moisture would leak out the seams either, but there should be no moisture in there to leak.......

Any leaks around door or the closed off vent on rear leak air INTO the stove when chimney is warm. Not smoke out. The warm chimney has rising gasses that cause a lower pressure area in flue, pipe, and chimney allowing the higher atmospheric pressure in the house to leak IN. This would allow the fire to burn with intake dampers closed. (that's actually the patented name of them when Bob Fisher's father, Baxter invented them. So your terminology calling them dampers is correct.) Any leaks into chimney or pipe allows cooler indoor air to leak in, cooling the inner flue, causing the condensing issue you have as well.

6 inches above stove is not a good indication of pipe temp. Stove heat will affect the bimetallic spring that senses pipe temperature. Try it at least one pipe section above stove, then compare to the temp of the pipe just before it dumps into chimney. That will show you temperature drop at the top of connector pipe. Double that reading will be the internal gas temp entering chimney. Then you can estimate how much loss you have to the top. Not much with one section of chimney. If you can get a temp reading inside flue near the top, you can correlate 250* at the top to your inside measurements.
Double wall pipe inside will help tremendously.

Split everything but the smallest pieces.
As bholler mentions, rounds simply do not dry. Drying time starts when split, not cut.

Thanks again, coaly - one of the knobs had bad threads so I bought a replacement from Doug Barr of Barr Castings. He called them draft control knobs so I adopted that terminology. But intake dampers works for me!

And not sure if you're familiar with the weather here, but summer high temperatures average 85 to 95 degrees, with usually a couple of weeks of >100. Afternoon RH is usually in the low to mid 20's, and sometimes lower. And my woodyard gets about 12 hours of sun around the solstice. My logs get bucked soon if not immediately after felling, which along with stacking on pallets, and the remainder of my reply to bholler, may explain why I've had good success with that system.

 

[coaly]

Wow, that's a high ceiling. I'd bet you're not even putting 250* into the chimney.
Double wall for sure there will get more heat into your chimney and make the stove run far different. (air dampers closed more saving fuel) Then it won't matter if you're moving air over the pipe as much.

That is a Listed type firebox that started in 1979 with a pre 1980 flat top door. (With Fireplace legs too)
The following year that type door was dropped for the arched top, and a UL tag was affixed to a rear shield. 1979, the Fireplace Series was offered with the bent corner firebox like you have called the III. The single door stoves became VI. (IV was reserved for Fireplace Series with glass, and there was no V.) Only during 1979 was offered the old style doors, or the new optional Cathedral style. So that year there was a mix of old and new boxes with old or new doors. You have one of those transition stoves. New Listed box, old doors. Tags started in 1980. Single door stoves had no baffle that was added to the III Fireplace Series.
All the stoves were tested using other testing criteria before this time. There was just no standardization of testing until UL testing was accepted as the standard nationwide.

Someone pick bholler up off the floor if those clearances and floor protection are what I think they are.

 

[bholler]

Thanks, bholler - I don't have a moisture meter so I can't give you an empirical answer to that. However, most of those bigger unsplit pieces season in full sun (check my avatar picture) and not many clouds here for a good six months), off the ground on pallets, for at least two summers. Many of them are cut during the dormant season (I cut all my own wood), which really enhances seasoning. The fact that they burn well enough through the night with the intake draft knobs shut tight makes me think they are sufficiently seasoned. And in my second reply to coaly, you'll see that my only creosote problems are the leakage.

A 6" round might season in 2 years. But probably not. Anything over that not a chance. And if you have creosote leakage you have a creosote problem

 

[bholler]

Wow, that's a high ceiling. I'd bet you're not even putting 250* into the chimney.
Double wall for sure there will get more heat into your chimney and make the stove run far different. (air dampers closed more saving fuel) Then it won't matter if you're moving air over the pipe as much.

That is a Listed type firebox that started in 1979 with a pre 1980 flat top door. (With Fireplace legs too)
The following year that type door was dropped for the arched top, and a UL tag was affixed to a rear shield. 1979, the Fireplace Series was offered with the bent corner firebox like you have called the III. The single door stoves became VI. (IV was reserved for Fireplace Series with glass, and there was no V.) Only during 1979 was offered the old style doors, or the new optional Cathedral style. So that year there was a mix of old and new boxes with old or new doors. You have one of those transition stoves. New Listed box, old doors. Tags started in 1980. Single door stoves had no baffle that was added to the III Fireplace Series.
All the stoves were tested using other testing criteria before this time. There was just no standardization of testing until UL testing was accepted as the standard nationwide.

Someone pick bholler up off the floor if those clearances and floor protection are what I think they are.

Yeah not so good

 

[coaly]

I suppose if you shut the intake dampers fully, left it die, and the next day colder heavier air outside dropped down the pipe, the pressure inside pipe (atmospheric) could be higher than in the house for other reasons.
Example; If you have another heat source on, such as electric, the heated air rises out the leaky windows high in the home. Air escaping puts the house in a low pressure area, "depressurized" lower than inside the flue and pipe. This would push moisture that was on the pipe walls inside outward. At this point it would also be difficult to start a fire to get it drafting without opening a window.
Crack a window to allow the equalization of pressure inside and out, and your strange weeping through joints will probably stop. Then you know you have a depressurized house.

I see you're near 530 feet elevation. That gives you higher atmospheric pressure than being in the mountains, at lower pressure. Lowering pressure in the house has a greater effect the closer to sea level with more pressure pushing down chimney with a cold flue.

 

[coaly]

I call 'em Draft Caps.
I think I got that years ago from Barr's website. (he has the original Fisher molds)
Something like "Stove dampers, knobs, controls, draft caps, whatever you call 'em, we have them".
The originals were a 2 inch black iron pipe cap, so "draft cap" felt right to me.

 

[Todd67]

I didn't notice it mentioned yet, but have you tried using an incense stick to see if your stove is sucking air in from the rear flue cover and draft caps? It can help verify if your stove is sucking air in when the draft caps are closed all the way.

 

[Todd67]

@firekindler , do you still have the creosote problem?

 

[firekindler]

I suppose if you shut the intake dampers fully, left it die, and the next day colder heavier air outside dropped down the pipe, the pressure inside pipe (atmospheric) could be higher than in the house for other reasons.
Example; If you have another heat source on, such as electric, the heated air rises out the leaky windows high in the home. Air escaping puts the house in a low pressure area, "depressurized" lower than inside the flue and pipe. This would push moisture that was on the pipe walls inside outward. At this point it would also be difficult to start a fire to get it drafting without opening a window.
Crack a window to allow the equalization of pressure inside and out, and your strange weeping through joints will probably stop. Then you know you have a depressurized house.

I see you're near 530 feet elevation. That gives you higher atmospheric pressure than being in the mountains, at lower pressure. Lowering pressure in the house has a greater effect the closer to sea level with more pressure pushing down chimney with a cold flue.

Apologies for delayed reply - stopped getting email notices of subsequent posts for some reason and it's been a particularly full week. A: There is no other heat source in the house.
B: The draw is always vigorous, and the windows stay closed all winter. Cracking a window all night will likely result in greatly increased wood usage and decreased comfort, so I would likely try the double wall black connector pipe first.
C: I live in the hills outside of town, and am actually at 1600-1800'.
D: It is rare that the fire totally dies at night, or while I'm gone all day. There's almost always some coals, and often a significant bed when opened.

Thanks again.

 

[firekindler]

@firekindler , do you still have the creosote problem?

Apologies for delayed reply - stopped getting email notices of subsequent posts for some reason and it's been a particularly full week.
Good suggestion about the incense sticks; thank you very much. I'll pick one up and experiment. And since getting educated by you folks, I've been experimenting with keeping the draft caps cracked. Still got the creosote issue, however.

 

[coaly]

Cracking a window close to the fuel burning appliance allows it to get the proper air pressure and oxygen. The theory is, the air entering is used by the stove, and exhausted instead of letting the stove draw from every air leak possible in the house. This frequently causes drafts in parts of the home where there shouldn't be. Many tight homes require this to prevent a sluggish stove or difficult starting.

I've installed PVC intake vents behind stoves finding the customer plug it shut with rags when they feel the cold air coming in. I explain to them, the stove will use the same amount of air if it comes from the intake nearby, or across the house from their bedroom. Would they rather have cold air come all the way across the house, or from right next to the stove? That vent is also built with an elbow facing upward on the inside, and downward outside to prevent warm indoor air from leaking out. (it won't drop down the pipe) Air only moves through the vent when indoor pressure becomes lower than outside, or when being used by appliances such as dryers, range and bath exhaust fans, or other fuel burning appliances vented to the outside, overpowering the chimney. This prevents the "dirty chimney" smell around fireplaces where there are negative pressure issues in a home too.
I don't see that going on in your case. You would know when opening the stove door when not burning, you would get a nasty chimney smell coming through the stove.

I'm only seeing too much cooling before the chimney.
AND clearance issues. I'd start measuring around the stove to combustibles. 36 inches to that stove to any combustible material without proper heat shielding.

 

[Corey]

My .02 -

You have way too much exposed single wall stove pipe. 12 feet of 6" diameter pipe is capable putting out A LOT of heat into the room. This is causing you to burn low, smouldering fires - especially as you mention, overnight. Low smouldering fires = lots of creosote, cool flue temps, etc which make the 'creosote leak' problem even worse. Plus, unless you are burning hot enough to make the pipe glow red, even a hot fire isn't really 'burning out' any accumulated creosote.

Some mention of moisture was made, but even the driest wood MAKES moisture when it burns... hydrocarbons + oxygen = carbon dioxide + WATER. If your exposed pipe isn't at least 212 F all the way up and out the roof, all the time, that water condenses and runs back down inside the pipe...plus any water that was in the wood to start... plus any moisture in the combustion air. And we haven't even considered rain getting in the pipe or back draft yet.

Insulated pipe isn't as bad as it sounds. There are only three ways heat is getting out of the stove - though the stove box itself, through the pipe walls, or out the top of the stack which creates your draft. Assuming "out the top" (draft) stays relatively the same, and you insulate the pipe, it just means hotter fires in the stove and more heat coming out the stove box. This will help burn more creosote before even going up the chimney. But the insulated pipe will also keep the interior pipe wall above the critical temp for water condensation and substantially reduce the 'dripping' problem.

The only issue is that insulated pipe may push you into an overdraft condition, so you may want to put a damper back in to prevent a runaway if you open the door with some fire still in the box.

 

[firekindler]

My .02 -

You have way too much exposed single wall stove pipe. 12 feet of 6" diameter pipe is capable putting out A LOT of heat into the room. This is causing you to burn low, smouldering fires - especially as you mention, overnight. Low smouldering fires = lots of creosote, cool flue temps, etc which make the 'creosote leak' problem even worse. Plus, unless you are burning hot enough to make the pipe glow red, even a hot fire isn't really 'burning out' any accumulated creosote.

Some mention of moisture was made, but even the driest wood MAKES moisture when it burns... hydrocarbons + oxygen = carbon dioxide + WATER. If your exposed pipe isn't at least 212 F all the way up and out the roof, all the time, that water condenses and runs back down inside the pipe...plus any water that was in the wood to start... plus any moisture in the combustion air. And we haven't even considered rain getting in the pipe or back draft yet.

Insulated pipe isn't as bad as it sounds. There are only three ways heat is getting out of the stove - though the stove box itself, through the pipe walls, or out the top of the stack which creates your draft. Assuming "out the top" (draft) stays relatively the same, and you insulate the pipe, it just means hotter fires in the stove and more heat coming out the stove box. This will help burn more creosote before even going up the chimney. But the insulated pipe will also keep the interior pipe wall above the critical temp for water condensation and substantially reduce the 'dripping' problem.

The only issue is that insulated pipe may push you into an overdraft condition, so you may want to put a damper back in to prevent a runaway if you open the door with some fire still in the box.

Thanks Corey, and once again, coaly - double wall pipe is on the agenda, as well as the shielding issue. Here's a question: did the Papa Bear come with gasketing on the door? coaly earlier said, "Make sure your door seal is clean..." Mine has no gaskets. If gaskets are stock that seems likely why I've still got such good coals 12-14 hours after tightening the draft caps down.

And while we're here, Blessings of the Season, everyone.

 

[coaly]

No gasket material was used on solid doors, only with glass.

Make sure the back of door that makes contact with channel iron door seal is clean with a wire wheel in a drill. Also buff the channel iron door seal on stove front. Metal to metal makes contact at 3 points all the way around. The raised portion on door makes contact in the center of channel iron and the edges of channel iron make contact on back of door. There is no clearance space for gasket material as built.

 

[firekindler]

I didn't notice it mentioned yet, but have you tried using an incense stick to see if your stove is sucking air in from the rear flue cover and draft caps? It can help verify if your stove is sucking air in when the draft caps are closed all the way.

New developments and observations - This morning was pretty chilly. I awoke to a stove full of coals. I loaded it with five pieces of wood, a little heavier than usual. The fire took off and was cranking hard in seconds, as expected. A few minutes later I noticed a small amount of smoke apparently leaking from the rear flue cover. That lasted a couple of minutes.
Also, two days ago I ran the brush through the pipe. Immediately afterward I checked the baffle and found very little residue on it from the cleaning. But each morning since there has been no creosote/moisture leaking through the pipes.
And my ex'es brother in law teaches physics in college. I asked him about the leakage and he responded. I think I'd have to take several college physics classes just to interpret his answer. I'd post it here but I'd probably get banned forever.