Creosote Question

[Blackwings29]

I had a baffle plate welded on my baby bear, and now I am having really bad creosol issues. I never burned without it, we added it before we installed. I called a stove place about inspecting it, and they told me that if they inspected it with the modification they would red tag it.
The creosol is so bad though that it drips out. I took the pipes apart, and the creosol is about 3/8 inch thick, and I can pull it out in about 4 inch lengths and its really glossy. I'm hopping if I have the baffle removed I wont have this issue. Any other suggestions?
Thank you so much. New to this forum, Fisher stoves, and wood burning.

 

[begreen]

Blackwings, this may have nothing to do with the baffle if it was correctly installed. Instead it could be either A) the wood is poorly seasoned or B) the stove is getting choked down to a smolder or C) both of these conditions. For sure get the chimney cleaned before burning more.

When was the wood cut, split and stacked? Describe how the stove is being run.

 

[Blackwings29]

Blackwings, this may have nothing to do with the baffle if it was correctly installed. Instead it could be either A) the wood is poorly seasoned or B) the stove is getting choked down to a smolder or C) both of these conditions. For sure get the chimney cleaned before burning more.

When was the wood cut, split and stacked? Describe how the stove is being run.

The wood was cut about a year ago. I have a wood tester, and the wood is fine. I run the stove around 400-550. I load the stove in the morning before work, and get it going again when I get home. It heats the house great, its just the creasol

 

[begreen]

When you test the wood, did you resplit it first, then test on the freshly split face of the wood? The reason I ask is that some hardwood like oak and hickory needs at least 2 yrs seasoning to get dry inside.

Can you explain with more detail on exactly the stove is run starting with loading and in particular how the air controls are set?

 

[Blackwings29]

Here is a picture of the baffle....maybe it's just to big? it's welded from the front to back, and the sides are open.

 

[begreen]

Looks like a bad design. The baffle should be closed at the sides and open at the top front by at least 2-3". Can you show the front weld?

 

[Blackwings29]

When you test the wood, did you resplit it first, then test on the freshly split face of the wood? The reason I ask is that some hardwood like oak and hickory needs at least 2 yrs seasoning to get dry inside.

Can you explain with more detail on exactly the stove is run starting with loading and in particular how the air controls are set?

2 pieces of wood front to back with coals in the middle, then 2 more pieces the other way. Open knobs all the way for air to come through, until about 600, then close them down all the way , then give it a couple of turns to open it a little.

 

[begreen]

Sounds like you are doing fine, but that baffle could be fighting you. Take a look at some of the baffle mods done here to see better examples.

And do recheck a few splits by the method I mentioned earlier, especially if there is oak in the stack. This could be a combination of issues.

 

[Blackwings29]

Looks like a bad design. The baffle should be closed at the sides and open at the top front by at least 2-3". Can you show the front weld?

 

[begreen]

This is simply wrong. Here is a thread on a very simple baffle for a Fisher.
https://www.hearth.com/talk/threads...d-fisher-more-heat-less-smoke-under-25.74710/
And here is an example of a stove with and without a baffle, illustrating from a side view the front gap. Who ever installed this baffle did not understand how it functions. It should be removed.
https://www.hearth.com/talk/threads/jotul-118-cleaning-out-ash.119001/#post-1593467

The baffle still may not be the root cause of the creosote. Can you describe the flue system? How is this stove connected to the chimney? That could be contributing. Creosote forms when the flue gases drop below 250F. If the flue has a long run of single-wall connector to the chimney that can cool down the gases to the point where they start to condense on the chimney walls. This can be especially true if the stove is connected to an exterior chimney.

 

[Blackwings29]

This is simply wrong. Here is a thread on a very simple baffle for a Fisher.
https://www.hearth.com/talk/threads...d-fisher-more-heat-less-smoke-under-25.74710/
And here is an example of a stove with and without a baffle, illustrating from a side view the front gap. Who ever installed this baffle did not understand how it functions. It should be removed.
https://www.hearth.com/talk/threads/jotul-118-cleaning-out-ash.119001/#post-1593467

The baffle still may not be the root cause of the creosote. Can you describe the flue system? How is this stove connected to the chimney? That could be contributing. Creosote forms when the flue gases drop below 250F. If the flue has a long run of single-wall connector to the chimney that can cool down the gases to the point where they start to condense on the chimney walls. This can be especially true if the stove is connected to an exterior chimney.

So, the pipe coming out of the stove is an 8 inch pipe connected to an elbow then goes up about 2 feet to a 6 inch reducer then about 3 feet to the ceiling, then goes to an insulated pipe through the attic and out the roof maybe about 6 feet. The pipe in the house was running in the too cold section of the thermometer. We are looking at getting a new elbow, and hook up the 6 inch adapter closer to the elbow and have mostly 6 inch going up. it is not connected to a chimney.

 

[begreen]

You know of course that you are not supposed to reduce the stove pipe size.

 

[Blackwings29]

You know of course that you are not supposed to reduce the stove pipe size.

No, I didn't know. The pipe that comes down out of the attic is a six inch pipe, so I figured I would reduce the pipe to fit it. So, do I just replace all my pipes? And cut a bigger hole in the roof....ect?

 

[begreen]

I am going to wait for the Fisher expert coaly to comment on how the stove burns on a reduced outlet. Which model Fisher is this?

 

[Blackwings29]

I am going to wait for the Fisher expert coaly to comment on how the stove burns on a reduced outlet. Which model Fisher is this?

It's a Fisher Baby Bear I believe. Where would I find the exact model number?
Here is a picture.

 

[begreen]

That is not a Baby Bear. Looks more like their Grandma Bear, but am not a Fisher expert.

Do you have a stove pipe thermometer? After the chimney pipe is cleaned try to keep the flue temps up to at least 300F for the beginning of the fire until the wood is all charcoal.

 

[Blackwings29]

That is not a Baby Bear. Looks more like their Grandma Bear, but am not a Fisher expert.

Do you have a stove pipe thermometer? After the chimney pipe is cleaned try to keep the flue temps up to at least 300F for the beginning of the fire until the wood is all charcoal.

Thank you SOOOO much for all your help. Yes, we do have a thermometer for the pipe. And I'll be waiting the reply from coaly to see what to do about the pipe. Thank you again.

 

[coaly]

Blackwings;
I gave you your own thread since this is not related to the "Smoke Shelf Baffle" I designed in the baffle thread where your question was posted.

You have a Grandma Bear Fireplace Series stove. Baby is the smallest single door stove made by Fisher. Grandma is a double door stove in the Fireplace Series, so named to be able to burn with open doors with a screen in place for fire viewing. Single door stoves require 6 inch pipe and chimney. Fireplace Series were designed with 8 inch outlet. Pipe and chimney flue size can not be legally reduced in size. This stove will technically work reduced to 6, and there are many in service with smoke shelf baffles installed with a reduced chimney flue. Your firebox size is smaller than the largest single door stove that was designed for 6 inch, but the double door being able to run open with screen in place is the reason for the "oversize" 8 inch outlet. Codes are written to simply not allow reduction in size so when a stove is connected with the proper size all the way, you can't cause a restriction in the venting. Codes do not take into consideration that your stove would physically work reduced.

First we have to clarify this;
You stated you have NO Chimney. (post #11 above) Is this single wall pipe all the way up and outside ???

 

[Blackwings29]

Blackwings;
I gave you your own thread since this is not related to the "Smoke Shelf Baffle" I designed in the baffle thread where your question was posted.

You have a Grandma Bear Fireplace Series stove. Baby is the smallest single door stove made by Fisher. Grandma is a double door stove in the Fireplace Series, so named to be able to burn with open doors with a screen in place for fire viewing. Single door stoves require 6 inch pipe and chimney. Fireplace Series were designed with 8 inch outlet. Pipe and chimney flue size can not be legally reduced in size. This stove will technically work reduced to 6, and there are many in service with smoke shelf baffles installed with a reduced chimney flue. Your firebox size is smaller than the largest single door stove that was designed for 6 inch, but the double door being able to run open with screen in place is the reason for the "oversize" 8 inch outlet. Codes are written to simply not allow reduction in size so when a stove is connected with the proper size all the way, you can't cause a restriction in the venting. Codes do not take into consideration that your stove would physically work reduced.

First we have to clarify this;
You stated you have NO Chimney. (post #11 above) Is this single wall pipe all the way up and outside ???

The pipe in the house is a regular stove pipe, and in the attic and out through the roof is insulated pipe. I was thinking more of a fire place chimney when saying I didn't have a chimney. It just angles out and up.

 

[coaly]

OK, we'll assume the connector pipe goes into Class A Chimney at the ceiling (called the chimney support box) Wanted to make sure you had a system that would work first.
You have an insulated chimney, which is the best, BUT you need to check to see what kind of insulated chimney it is. (If you don't have the paperwork from it, you can take a section apart near the top, you can see where they go together what you have) There are two types. "Pack" which is stainless inside pipe with a dense heavy insulation between the inner and outside pipe. The other type is triple wall insulated, which is a stainless inner pipe with a second larger pipe, and finally a third outer pipe on the outside. Some will have only air between all the pipes and they cool the inner pipe so well, they run too cool and load up with creosote. The only triple wall pipe that should be used with your stove will have an insulation blanket wrapped around the inner pipe between the first and second pipe. This keeps the inner pipe hotter to prevent a large build up. The object is to keep inside flue temperature above 250* all the way to the top. So by monitoring the pipe temp just below the start of chimney, you know about what temp you have going into the insulated part of the system, and should not lose too much all the way up. If you try to keep the temp at 350, you can assume it may cool to 250 at the top. This is where you will get the greatest accumulation, at the coolest part. Time will tell as you check it frequently if you are running too cool.
Now you know what temps are ideal. Without any baffle, there can be so much heat lost up the chimney, the exhaust out the top can be far more than needed, so consider that lost heat that brings down the efficiency. Closing the damper partially slows down the exhaust flow, and also slows the air coming into stove, so it slows the burn as well. Slowing the velocity does make a difference in speed up the stack, but it doesn't make much of a difference in temperature until the fire slows due to slowing the incoming air down. The baffle plate directs flame to the stove top instead of letting it go straight up the pipe. The design of the baffle is what determines how much heat is left up, or soaks into the stove. Since you never ran the stove without a baffle, you may just be running too cool by not opening the air vents enough. (or closing the damper too much) See if you can maintain 300 to 350 mid burn cycle with your baffle style. It's an untested design, and not one used by Fisher.
Here is a factory "Smoke Shelf Baffle" that was used in later stoves the width of yours;



The square inches across the outlet pipe of your stove (8 inch round) would be 50.24 inches, so with a 8 inch pipe and chimney, you would need at least 50.24 square inches of space for the smoke to exit stove. This is "smoke space". Reduced down to 6 inch flue, you would need at least 28.25 square inches of smoke space. In other words, you can't make the space the exhaust need to travel smaller than the size going up. It will smoke when you open the doors, and not allow enough heat up to stay clean.
Does yours smoke inside when you open the doors slowly ?
This is the first sign of a exhaust restriction inside or outside of the stove.

Notice the baffle shown above closes off the sides and you can measure the opening easily. With yours, you will need to measure the opening for smoke to travel out, and figure the square inches you have by multiplying L X W of opening and adding each side together. The design looks like it would roll the smoke forward and maybe work well with doors closed, but my guess is that it may roll the smoke right out the door when they are open.

Off topic; is that a UL listed stove board under the stove, or a homemade tile or stone protector?

 

[Blackwings29]

OK, we'll assume the connector pipe goes into Class A Chimney at the ceiling (called the chimney support box) Wanted to make sure you had a system that would work first.
You have an insulated chimney, which is the best, BUT you need to check to see what kind of insulated chimney it is. (If you don't have the paperwork from it, you can take a section apart near the top, you can see where they go together what you have) There are two types. "Pack" which is stainless inside pipe with a dense heavy insulation between the inner and outside pipe. The other type is triple wall insulated, which is a stainless inner pipe with a second larger pipe, and finally a third outer pipe on the outside. Some will have only air between all the pipes and they cool the inner pipe so well, they run too cool and load up with creosote. The only triple wall pipe that should be used with your stove will have an insulation blanket wrapped around the inner pipe between the first and second pipe. This keeps the inner pipe hotter to prevent a large build up. The object is to keep inside flue temperature above 250* all the way to the top. So by monitoring the pipe temp just below the start of chimney, you know about what temp you have going into the insulated part of the system, and should not lose too much all the way up. If you try to keep the temp at 350, you can assume it may cool to 250 at the top. This is where you will get the greatest accumulation, at the coolest part. Time will tell as you check it frequently if you are running too cool.
Now you know what temps are ideal. Without any baffle, there can be so much heat lost up the chimney, the exhaust out the top can be far more than needed, so consider that lost heat that brings down the efficiency. Closing the damper partially slows down the exhaust flow, and also slows the air coming into stove, so it slows the burn as well. Slowing the velocity does make a difference in speed up the stack, but it doesn't make much of a difference in temperature until the fire slows due to slowing the incoming air down. The baffle plate directs flame to the stove top instead of letting it go straight up the pipe. The design of the baffle is what determines how much heat is left up, or soaks into the stove. Since you never ran the stove without a baffle, you may just be running too cool by not opening the air vents enough. (or closing the damper too much) See if you can maintain 300 to 350 mid burn cycle with your baffle style. It's an untested design, and not one used by Fisher.
Here is a factory "Smoke Shelf Baffle" that was used in later stoves the width of yours;

View attachment 123814

The square inches across the outlet pipe of your stove (8 inch round) would be 50.24 inches, so with a 8 inch pipe and chimney, you would need at least 50.24 square inches of space for the smoke to exit stove. This is "smoke space". Reduced down to 6 inch flue, you would need at least 28.25 square inches of smoke space. In other words, you can't make the space the exhaust need to travel smaller than the size going up. It will smoke when you open the doors, and not allow enough heat up to stay clean.
Does yours smoke inside when you open the doors slowly ?
This is the first sign of a exhaust restriction inside or outside of the stove.

Notice the baffle shown above closes off the sides and you can measure the opening easily. With yours, you will need to measure the opening for smoke to travel out, and figure the square inches you have by multiplying L X W of opening and adding each side together. The design looks like it would roll the smoke forward and maybe work well with doors closed, but my guess is that it may roll the smoke right out the door when they are open.

Off topic; is that a UL listed stove board under the stove, or a homemade tile or stone protector?

We cleaned out all the pipes from roof cap down, and bought new stove pipe and brought the six inch pipe down closer to the elbow. It seems work a lot better. It doesn't smoke in the house right now. The new pipes are staying warmer, now too at 350 and usually it was around 250-300. I'm going to see how this works with the creosote problem and maybe this summer redo all the pipes to 8 inches. I'll have to look to see what kind of insulated pipe is up there now, it's old though, because I can't buy anything to fit it. I'll also wait to measure for the smoke space when it warms up and adjust the baffle then.

The stove board under the stove is UL rated. I bought that at menards when I bought the stove.

I just want to say thank you again for all your help and advice.

 

[Blackwings29]

Also, the old 8 inch pipe I had in the house had a damper on it. The new 6 inch pipe I bought does not. Which way do you recommend?

 

[coaly]

As long as it's not an inspection problem, and you don't burn much with open doors, the 6 inch should work fine. One reason it's hotter now, is the larger the pipe or flue, the more the exhaust gasses expand and cool.
It should have a damper as close to stove as possible. It is required for open door burning since it then becomes the only control you have of the fire. Providing you have a screen.

 

[topoftheriver]

I just jumped in here after reading some of the comments. Referring to the 6" pipe, many cities and towns don't require the damper when there are air controls on the stove but as a precaution, I like to install a damper on the pipe for safety sake. It could possibly over kill but who wants a fire that could burn down the entire house? One other note. On occasions of high winds such as we get near the ocean, you can dampen the draft so that it doesn't suck all of the heat out of the stove. Generally you could adjust your air intake but i also think that the external chimney pipe damper helps with the high wind draft situation, in my view and from experience.

 

[BrotherBart]

"Referring to the 6" pipe, many cities and towns don't require the damper when there are air controls on the stove"

For my edification, please tell me any locality that requires a key damper in a stove pipe? And what an "external chimney pipe damper" is?