# Heavy creosote build up



## Zombie (Feb 3, 2021)

Hello everyone, this past weekend I got my new chimney installed and fired up the Grandpa Bear for the first time.  From advise received here, it is a 7" duravent class A.  It stands a 16', black 7" single wall inside with a 8-7 reducer at the stove outlet.  I have been burning round the clock since 6 'o clock on Jan 30th.  I was going to check it this Sat. but I was just coming back from the chicken coop this afternoon and happened to look up at the rain cap, not good.  As luck would have it, I haven't added any wood to it today because I was going to clean it out the ashes this afternoon.  I went up on the roof and got the rain cap off, it is a sticky mess.  It's so bad that there are drips on my metal roof and drips on the pipe under the cap.  According to the magnetic thermo I have on the stove pipe, it runs around 300 to 400.  The wood being burned is red oak, holly, white oak, and cherry blossom.  According to the moisture meter it is all between 18 and 25%.  Can someone tell me what is going wrong here?


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## Jan Pijpelink (Feb 3, 2021)

Did you measure the moisture content on a fresh re-split after it has been at room temp for 24 hrs? If not, you might have a false reading. How long has the wood been seasoned?


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## Zombie (Feb 3, 2021)

This is what'a going on.  I have another 4' section of chimney pipe, but did not install as I measured and met the 10/2 rule.


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## Zombie (Feb 3, 2021)

The red and white oak, a little less than a yr, the cherry blossom and holly about 8 months?


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## Zombie (Feb 3, 2021)

Yes that is how I measured it.


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## DAKSY (Feb 3, 2021)

25%! That's too much water in your wood. 18% & below is best...


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## Zombie (Feb 3, 2021)

I know 25% is high, but would it really cause this much build up this fast?


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## begreen (Feb 3, 2021)

Creosote can build up very quickly when the wood is wet especially when vented to a cold outdoor chimney.


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## Jan Pijpelink (Feb 3, 2021)

Zombie said:


> The red and white oak, a little less than a yr, the cherry blossom and holly about 8 months?


If you are not using a kiln, red and white oak usually does not dry under 1 year. That amount of creosote in such a short time means only one thing: wet wood.


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## Zombie (Feb 3, 2021)

The pipe does not seem to have much build up in it, there is a little shiny black build up in the top section of chimney but looking up through the clean out tee with a flashlight, there doesn't appear to be much or any in the middle and lower section of the chimney.


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## Jan Pijpelink (Feb 3, 2021)

Zombie said:


> The pipe does not seem to have much build up in it, there is a little shiny black build up in the top section of chimney but looking up through the clean out tee with a flashlight, there doesn't appear to be much or any in the middle and lower section of the chimney.


If you started burning on January 30 and on February 3 you have this amount of creosote, even at the top of your chimney, something is  wrong.


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## bholler (Feb 3, 2021)

Zombie said:


> The pipe does not seem to have much build up in it, there is a little shiny black build up in the top section of chimney but looking up through the clean out tee with a flashlight, there doesn't appear to be much or any in the middle and lower section of the chimney.


You are burning wood that is to wet in an old steel box stove with no secondary combustion system at all creosote buildup is a given.


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## Zombie (Feb 3, 2021)

If wet wood is to blame, that's an easy fix.  I'm really hoping something is not wrong with my setup. I am going to be installing a baffle plate in Grandpa.  The draft on the chimney is very good, I have not had any issue at all with smoke coming back in with the doors open, but is 16" enough? The smoke seems to want to follow my roof and come down toward the ground.


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## bholler (Feb 3, 2021)

Zombie said:


> If wet wood is to blame, that's an easy fix.  I'm really hoping something is not wrong with my setup. I am going to be installing a baffle plate in Grandpa.  The draft on the chimney is very good, I have not had any issue at all with smoke coming back in with the doors open, but is 16" enough? The smoke seems to want to follow my roof and come down toward the ground.


With dry wood it will certainly be better but with that stove you are always going to have creosote buildup a baffle will probably make it worse


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## moresnow (Feb 3, 2021)

No offense but your seasoning period is nowhere near long enough. The large rounds in your stack are likely very, very wet. Couple that with a old school stove. You get a mess. Keep it clean if you are going to continue burning. Good luck.


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## Zombie (Feb 3, 2021)

No offense taken.   Thank you for the replies, I am getting some wood delivered, and I know hat this stuff was on the damp side, I didn't intend to continue running it once the seasoned wood gets delivered.  The last few days were me just testing it out to get a feel for how the stove would run with this chimney setup, but man, I never expected to see this much buildup this fast.  When I was younger, my dad would use a creosote log about once a month and when I would sweep, all I ever got was greyish powder.  Are those type of logs ok with a class A?  Forgive my ignorance I'm still learning and this site has been wonderful for that.


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## bholler (Feb 3, 2021)

Zombie said:


> No offense taken.   Thank you for the replies, I am getting some wood delivered, and I know hat this stuff was on the damp side, I didn't intend to continue running it once the seasoned wood gets delivered.  The last few days were me just testing it out to get a feel for how the stove would run with this chimney setup, but man, I never expected to see this much buildup this fast.  When I was younger, my dad would use a creosote log about once a month and when I would sweep, all I ever got was greyish powder.  Are those type of logs ok with a class A?  Forgive my ignorance I'm still learning and this site has been wonderful for that.


It is very unlikely the wood you get delivered will be any drier.  Creosote logs and chemicals can help convert that glaze into something easier to clean.  Just make sure you don't use any salt based ones.  I don't think they are sold anymore but check


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## Zombie (Feb 3, 2021)

bholler said:


> With dry wood it will certainly be better but with that stove you are always going to have creosote buildup a baffle will probably make it worse


From what I have been reading in the classic forum, the baffle is supposed to make it burn cleaner.  @coaly has some great write ups on the subject.  Are there any other things I can do to run cleaner?


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## Zombie (Feb 3, 2021)

bholler said:


> It is very unlikely the wood you get delivered will be any drier.  Creosote logs and chemicals can help convert that glaze into something easier to clean.  Just make sure you don't use any salt based ones.  I don't think they are sold anymore but check


I hope it is, the guy says it is ready to burn and I will be checking it when he delivers it.  OK, I will make sure no salt based logs.  Suggestions on a good sweep brush?


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## bholler (Feb 3, 2021)

Zombie said:


> From what I have been reading in the classic forum, the baffle is supposed to make it burn cleaner.  @coaly has some great write ups on the subject.  Are there any other things I can do to run cleaner?


It wastes less heat up the chimney and can possibly create a little secondary combustion in the firebox if temps are high enough.  But with wet wood you will never get there.  And even then the stove will never burn clean and will only be a bit more efficient


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## bholler (Feb 3, 2021)

Zombie said:


> I hope it is, the guy says it is ready to burn and I will be checking it when he delivers it.  OK, I will make sure no salt based logs.  Suggestions on a good sweep brush?


They all say that and 95% of them are lying.

I would go with a rotary cleaner like the soot eater.


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## Zombie (Feb 3, 2021)

bholler said:


> They all say that and 95% of them are lying.
> 
> I would go with a rotary cleaner like the soot eater.


We shall see this weekend, you are probably right and it will be too wet. I just looked up the sooteater, I like that.  I'll order one tonite.


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## Zombie (Feb 3, 2021)

Being more efficient was my goal, that way this stove will eat less wood and smoke less.


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## bholler (Feb 3, 2021)

Zombie said:


> Being more efficient was my goal, that way this stove will eat less wood and smoke less.


It will eat less wood.  Smoking less comes from dry wood and higher temps not a baffle


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## coaly (Feb 3, 2021)

Other than wet wood, no one has mentioned operator error.

Are you using a flue pipe damper?
How far are you closing the air dampers overnight?
You mentioned the pipe thermometer reading 300 - 400, but is it always that hot when smoke is present?

Do you hear any sizzle or hiss? Any moisture coming out of the ends of wood?


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## coaly (Feb 3, 2021)

The top of that chimney pipe does not look high enough in that picture. Could be picture angle. Before you add a baffle, what does it measure on a horizontal line from top of flue outlet to roof?


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## MMH (Feb 3, 2021)

Check chimney height against stove manufacturers recommendations; there is no way the wood is dry enough, let alone in rounds of that size. Oak takes minimum 2 years, the others I’d guess at least a year in your climate. Buying wood also rarely remedies this situation, it is what it is. I think begreen is right a baffle might help a tiny bit but all in all the stove is and older model with no secondary systems, your going to burn on the dirty side and have creo build up. The soot water is good you won’t be disappointed with it. As far as your main issue/question, properly season the wood, wet wood will build creo fast. Also, unless you got a real good close up look at all of that pipe, don’t take shining a light up and seeing it at the other end as there’s no glaze in there. Good luck.


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## Zombie (Feb 3, 2021)

coaly said:


> Other than wet wood, no one has mentioned operator error.
> 
> Are you using a flue pipe damper?
> How far are you closing the air dampers overnight?
> ...


I don't have a flue pipe damper installed in this setup, but I am going to get 1. I set both damper knobs at wide open when loading and monitor temps then dial it back slowly to 1 full turn open to level it out and get it cruising, any further closed than 3/4 of a turn open and the thermo drops below 300. I haven't seen any moisture coming out of the wood but did hear some sizzle with 1 load.  On a horizontal line it measures just over 10'.  I have another 4' section of pipe I haven't added yet.  The main reason for getting a load of wood was because I only have about 1 cord on hand, and I know that it's no quite ready to burn.


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## kennyp2339 (Feb 4, 2021)

I'm not going to comment on the wood, you seem to know whats going on with that, but you have to get those temps hotter, cruise around 500-600 for a cleaner burn.


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## Zombie (Feb 4, 2021)

kennyp2339 said:


> I'm not going to comment on the wood, you seem to know whats going on with that, but you have to get those temps hotter, cruise around 500-600 for a cleaner burn.


Flue or stove top?


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## Zombie (Feb 4, 2021)

Also, on the grandpa bear, where would be the ideal location for a thermo on the stove top?


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## Zombie (Feb 4, 2021)

Thank you again to everyone who has responded, it is much appreciated.  This is my first opportunity to have a wood stove in my house since I was a kid/teen, and I've learned more from reading here than I did when I was younger.


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## kennyp2339 (Feb 4, 2021)

Zombie said:


> Flue or stove top?


stove top, but you may see those temps or slightly higher temps on your single wall black pipe since you dont have a baffle in the stove or a pipe damper in the chimney, It wont hurt anything running that warm.


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## JMac1999 (Feb 4, 2021)

Zombie said:


> I hope it is, the guy says it is ready to burn and I will be checking it when he delivers it.  OK, I will make sure no salt based logs.  Suggestions on a good sweep brush?


Soot Eater makes a great chimney cleaner, Pretty cheap as well.


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## coaly (Feb 4, 2021)

Zombie said:


> Also, on the grandpa bear, where would be the ideal location for a thermo on the stove top?


Without baffle the rear top gets hotter  than front. The front is more of simmer. With baffle the front becomes hotter which is what you want to stabilize temperature spikes up the stack.
I always put it on the step so it’s easy to read instead of laying flat on the top.

The graduations and heat zones are for single wall pipe. You have to know what the temps are at different points in the system for creosote formation.

The surface temperature of pipe is about 1/2 the actual flue gas temp. With a baffle I get 250 on the pipe before entering chimney and 500 stove top. So 500 stove top correlates to 500 internal flue temp which would cool in some chimneys to 250 at top, hence the cool zone mark on thermometer at 250. Since each system cools differently, the thermometer is only a guide.

An IR surface thermometer is a great investment. At operating temperature with screen removed you can get an actual temp reading a foot down on the flue sidewall and see what that corresponds to on the pipe surface at bottom. Then you know where to run it without guess work. You’ll find drastic temperature differences on different parts of the stove too.  Since the BTU output is determined by the temperature of each square inch of surface area, you get a good idea of how complicated it is.


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## Zombie (Feb 4, 2021)

kennyp2339 said:


> stove top, but you may see those temps or slightly higher temps on your single wall black pipe since you dont have a baffle in the stove or a pipe damper in the chimney, It wont hurt anything running that warm.


Ok, that's what I have been seeing.  I have seen as high as 650ish on the step of the stove, pipe temps at that time were a little over 375, I try to maintain 300 on the stove pipe.


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## Zombie (Feb 4, 2021)

coaly said:


> Without baffle the rear top gets hotter  than front. The front is more of simmer. With baffle the front becomes hotter which is what you want to stabilize temperature spikes up the stack.
> I always put it on the step so it’s easy to read instead of laying flat on the top.
> 
> The graduations and heat zones are for single wall pipe. You have to know what the temps are at different points in the system for creosote formation.
> ...


I have matched this against the magnetic thermos and they aren't that far off.  Here are a couple more ahots of the chimney from different angles.


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## logfarmer (Feb 4, 2021)

You could also bake the wood a little longer to help drive some moisture out too before damping down.


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## coaly (Feb 4, 2021)

Those angles look better.
Wind has a lot to do with creosote formation at the top.
Your prevailing winds are probably coming from the other side of your house when you notice the smoke coming down the roof.
I know a few people that never had creosote issues until storms with high winds, sleet or snow cooling the lid and blocking the screen. With a metal roof, I see no reason to need a spark screen. The Woodburners Encyclopedia has a table of resistance values for chimney parts and gives a spark screen the same resistance as one 45* elbow.

Here is the formula for figuring how much water vapor firewood produces;
Water vapor is a by product of combustion when hydrogen is present. Oven dry wood contains 6% hydrogen. One pound oven dry wood produces .54 pounds of water vapor. Wood with moisture content of 25% contains another 1/4 pound of water vapor. When entire vent system is above condensing point of 250* flue gasses rarely condense.
The formula for calculating water vapor formed burning any fuel is 9 being the ratio of the molecular weight of water to hydrogen. Every pound of hydrogen becomes 9 pounds of water. So a fuel containing approx. 6% hydrogen such as dry wood, produces .54 pounds water for every pound burned.


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## Zombie (Feb 4, 2021)

coaly said:


> Those angles look better.
> Wind has a lot to do with creosote formation at the top.
> Your prevailing winds are probably coming from the other side of your house when you notice the smoke coming down the roof.
> I know a few people that never had creosote issues until storms with high winds, sleet or snow cooling the lid and blocking the screen. With a metal roof, I see no reason to need a spark screen. The Woodburners Encyclopedia has a table of resistance values for chimney parts and gives a spark screen the same resistance as one 45* elbow.
> ...


Funny you should mention high winds and snow, Sat. When I started burning, it snowed, and then turned to freezing rain.  It has been between 21 and 36 degrees every day.The winds around here have been a steady 12 mph with gusts upwards of 20-25 for much of the last week also.  The screen was intended to keep birds and things from trying to build a nest in my chimney over the months that the stove will not be in use.


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## Zombie (Feb 4, 2021)

logfarmer said:


> You could also bake the wood a little longer to help drive some moisture out too before damping down.


I was hoping that having the rounds very close to the stove for a couple days before loading them would help dry them out as well, my draft is pretty strong, even with a 16' chimney, and if I try to leave it more open to do this (I tried) the stove temps start to go too high and I have to back it down.  However, I was letting the stove pipe thermo get to right 500 and sit there for about 15 mins or so to get the wood going really good, even to the point where the chimney was very warm, almost hot to the touch, but I could still lay my hand on it.


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## EatenByLimestone (Feb 4, 2021)

My first year I was burning free pallets because I didn't have dry wood.  Some also burn compressed sawdust logs.   With the known dryness oc the pallets and sawdust, you can mix some wetter wood in.


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## Zombie (Feb 4, 2021)

EatenByLimestone said:


> My first year I was burning free pallets because I didn't have dry wood.  Some also burn compressed sawdust logs.   With the known dryness oc the pallets and sawdust, you can mix some wetter wood in.


Most of the free stuff arounf here ends up being chemically treated and pine, because trust me, I thought about that too, lol.  I had not however thought about compressed sawdust logs, I'm going to have to look that up, thank you sir.


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## Jan Pijpelink (Feb 4, 2021)

Zombie said:


> Most of the free stuff arounf here ends up being chemically treated and pine, because trust me, I thought about that too, lol.  I had not however thought about compressed sawdust logs, I'm going to have to look that up, thank you sir.


There is nothing wrong burning pine.


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## Zombie (Feb 5, 2021)

Jan Pijpelink said:


> There is nothing wrong burning pine.


I've always been told that burning large quantities of pine can build creosote quicky due to it's sappy nature.


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## bholler (Feb 5, 2021)

Zombie said:


> I've always been told that burning large quantities of pine can build creosote quicky due to it's sappy nature.


Not true at all


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## Jan Pijpelink (Feb 5, 2021)

Zombie said:


> I've always been told that burning large quantities of pine can build creosote quicky due to it's sappy nature.


Nonsense. All wet wood creates creosote. There are millions of wood burners west of the Mississippi who only have soft woods like pine available. What about them? I have burnt pine for a whole season (several seasons) with only a half cup of soot after a cleaning at the end of the season.
Looking at your pictures (after a few days burning) you just contradicted your self.


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## Zombie (Feb 5, 2021)

Jan Pijpelink said:


> Nonsense. All wet wood creates creosote. There are millions of wood burners west of the Mississippi who only have soft woods like pine available. What about them? I have burnt pine for a whole season (several seasons) with only a half cup of soot after a cleaning at the end of the season.
> Looking at your pictures (after a few days burning) you just contradicted your self.


I appreciate all of you who go out pf there way tp help people learn about this craft. 
It's great that this community of people exist.  I don't expect kid gloves at all when I am being corrected, but there's no need to be rude about it, and I am not trying to contradict myself.  I was simply stating that, that is what I have been told from every single old timer or wood burner I have ever spoken to.  I am here to have fun, share my story,and gain more knowledge on this subject so I can become skilled at operating a wood stove with the CORRECT and safest practices.  Please do not think I am ignorant.  Even if I think  I know the answer to something I will still ask if I see one of you make a comment that goes against what I have always heard to be true from people with more experience than I.  If I have been misinformed my whole life, then I am glad that I learned the otherwise.


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## Jan Pijpelink (Feb 5, 2021)

I was not trying to be rude, just pointing out that *all* wet wood makes creosote.


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## Zombie (Feb 5, 2021)

Jan Pijpelink said:


> I was not trying to be rude, just pointing out that *all* wet wood makes creosote.


Yes, I didn't specify that I ment dry pine.  Maybe it's the disconnect where I can't hear/see you to get how you ment it.


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## bholler (Feb 5, 2021)

Zombie said:


> I appreciate all of you who go out pf there way tp help people learn about this craft.
> It's great that this community of people exist.  I don't expect kid gloves at all when I am being corrected, but there's no need to be rude about it, and I am not trying to contradict myself.  I was simply stating that, that is what I have been told from every single old timer or wood burner I have ever spoken to.  I am here to have fun, share my story,and gain more knowledge on this subject so I can become skilled at operating a wood stove with the CORRECT and safest practices.  Please do not think I am ignorant.  Even if I think  I know the answer to something I will still ask if I see one of you make a comment that goes against what I have always heard to be true from people with more experience than I.  If I have been misinformed my whole life, then I am glad that I learned the otherwise.


After seeing many posts from Jan for a long time I am positive they didn't mean to be rude it just came off wrong.  But yes many old-timers in the east believe burning pine is bad and will create creosote.  It simply is not true.  Pine in general does not have the btus of most hardwoods simply because it is not as dense.  But that low density also means it dries fast which is good when you are starting out.  It is also how it got it's bad name.  People would burn wet hardwoods all year filling the chimney with creosote and at then when they ran out of hardwood they would throw in some pine they had laying around and the chimney would catch fire.  It did this because the pine was actually burning hot the way it should and it was actually the hardwood that caused the problem.  But that's not how they saw it.


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## Zombie (Feb 5, 2021)

That makes a lot of sense, sry for taking it the wrong way.  I have a lot of pine that has been cut for mutliple years, I use it for my fire pit.  I probably have 5 or 6 cords lying around all over the place.  Looks like I'm back in business then.


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