Hey new here was hoping to get some answers on my old big double door fisher wood stove. I clean my chimney and about a week later seems like it needs cleaned again (smoke comes out stove when I open doors so I know it's plugged up again) the stove pipe off the stove is 8" and goes into my brick chimney that is approx. 6x7" I run stove with dampers cracked open during the day but close dampers at night so fire will burn all night and also afraid a chimney fire will start while I'm sleeping so I keep them shut. I burn seasoned fir,alder,hemlock wood mostly fir though. Guys got any ideas?
Fisher wood stove creosote build up
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jatoxico
Minister of Fire
Many potential things going on. First is the chimney fully lined to the cap or does the stove pipe just go into the old masonry chimney a few feet? If the pipe is stuck up the chimney a few feet w/o a positive connection to the existing liner that does not meet code, can produce excess creosote and is dangerous.
Turning down the air will produce more creosote so it defeats the purpose to close it at night to not have a chimney fire. Rather you have to burn as hot as you need to (given your setup and conditions) to avoid creating excessive creosote in the first place. Low and slow in an old stove can often = creosote factory. You must send enough heat up the flue to keep the gases hot so they won't condense in the flue.
Wood quality is another possible issue. Seasoned means many things to many people. Modern stoves need wood with a verified moisture content of <20%. This can take 2 seasons or more after it's been split and stored in a good location. Not that certain species can't be "seasoned" to 20% in a single year but wet wood is one of the most common problems. So, while old stoves tolerate wet wood better than the new ones they still benefit from drier wood since it produces more heat w/ less creosote.
Turning down the air will produce more creosote so it defeats the purpose to close it at night to not have a chimney fire. Rather you have to burn as hot as you need to (given your setup and conditions) to avoid creating excessive creosote in the first place. Low and slow in an old stove can often = creosote factory. You must send enough heat up the flue to keep the gases hot so they won't condense in the flue.
Wood quality is another possible issue. Seasoned means many things to many people. Modern stoves need wood with a verified moisture content of <20%. This can take 2 seasons or more after it's been split and stored in a good location. Not that certain species can't be "seasoned" to 20% in a single year but wet wood is one of the most common problems. So, while old stoves tolerate wet wood better than the new ones they still benefit from drier wood since it produces more heat w/ less creosote.
The 8" pipe comes off the top of the stove goes up 2ft and a 90 elbow and goes about another foot through the brick wall into the chimney the chimney itself has a brick liner.
jatoxico
Minister of Fire
OK. Is this an interior or exterior chimney? Cold exterior chimneys (like mine) are more prone to cooling off and making 'sote. Also if there is a clean out door, check that it's tight and not allowing cool air in that could dilute the flue gas w/ cool air. All else (eg wood) still applies. Which stove do you have? Going from 8' to the 6x7 may also be another factor but @coaly will know better.
It is an interior chimney. And it does have a clean out door behind stove. The stove is the big double door fisher the grandpa bear I believe.
jatoxico
Minister of Fire
Check the clean out. I can't say if 6x7 is too small for you, hopefully coaly will chime in soon. New stove to you or been running for awhile? You should have thermometers on stove top and the pipe to help you know what you're doing temp wise. 500 stove top while cruising w/ a load is common. Temp on stove pipe has to factor in distance from stove and type of pipe to be understood but if you can give some typical temps folks can tell you if you're in the bll park or need to run much hotter.
Ok. I bought the house 5 years ago the primary heat source in the house is the wood stove I use it constantly during the winter cleaning the chimney about 4 times during my burning season. Which seems like it needs to be cleaned more often than that. Which i dont think is right. Previous owner lived there for 25yrs. With that same set up I haven't changed a thing besides putting new 8" pipe from stove to chimney. I am almost thinking about buying a new wood stove that runs 6" pipe or would it be better to neck the 8" pipe down to 6"? Or would that be worse?
jatoxico
Minister of Fire
Well I'm not going to talk you out of buying a new stove. They burn cleaner and use less wood but...Fisher is a fine stove and you may just need to make a few changes in your burning habits or with the fuel. Describe what you're burning. How long has it been cut, split and stacked (CSS)? This is critical and will be even more important if you change stoves to a newer EPA certified unit.
Necking down a chimney is technically a code violation but many stoves can successfully be run on a smaller than spec'ed flue. You can also add a simple baffle to the Fisher (https://www.hearth.com/talk/threads...d-fisher-more-heat-less-smoke-under-25.74710/) to improve it's performance.
Check the cleanout (not just the ash dump in the firebox but the cleanout too) and get some good dry wood.
Necking down a chimney is technically a code violation but many stoves can successfully be run on a smaller than spec'ed flue. You can also add a simple baffle to the Fisher (https://www.hearth.com/talk/threads...d-fisher-more-heat-less-smoke-under-25.74710/) to improve it's performance.
Check the cleanout (not just the ash dump in the firebox but the cleanout too) and get some good dry wood.
When I burn fir I usually CSS let it sit for the summer and seems dry? The hemlock I have been burning this year has been sitting in barn for around 2 years. I have been burning mainly that hemlock wood so far this year and have noticed more creosote this year than normal but I have also noticed it does not burn as hot as the fir does so I'm thinking that may be the biggest issue.
Your running the chimney too cool. Stove make or model doesn't matter, it's all about the chimney.
This is the equivalent of driving a car 25 mph because you're afraid to drive it too fast. You get rear-ended because you're causing the hazard.
This is all about flue temperature and you need to know what it is.
With a clean chimney, put a stove pipe thermometer on the pipe close to where it goes into chimney. When smoke is present, keep the temperature hot enough to keep flue gasses above 250* all the way up. This is a guess of how much the inside flue cools with or without insulated liner, indoor or outdoor chimney........ The first factor is the temperature you're sensing on the outside of pipe is about 1/2 the inside flue gas temp. So 300* is approximately 600 flue gas. This should be enough heat loss up the chimney in a normal situation, excessive chimney height or inner flue diameter requires more heat. It's not the stove, fuel sounds fine, and keeping it hotter prevents creosote buildup. Too much heat left up cuts into heating efficiency. So you have to find the right amount to leave up for the fuel, and heating requirements. (too large of a stove for an area requires slower burning causing problems, so we need to make sure the stove is sized properly. The first post in this thread will identify your stove; https://www.hearth.com/talk/threads/everything-fisher.48309/)
The reason for build up is any fossil fuel creates water vapor during combustion. Wet or wood containing excess moisture compounds the problem. Smoke particles stick to the sides when the water vapor condenses below 250* and can build up rapidly. In the coaling stage this is not a factor.
You should have a stove pipe damper for open door burning, but leave that open until you get the creosote build up manageable. Burning hard woods can get down to one cleaning during the season or at season end only, you will have to go by the norm for the soft woods in your area.
This is the equivalent of driving a car 25 mph because you're afraid to drive it too fast. You get rear-ended because you're causing the hazard.
This is all about flue temperature and you need to know what it is.
With a clean chimney, put a stove pipe thermometer on the pipe close to where it goes into chimney. When smoke is present, keep the temperature hot enough to keep flue gasses above 250* all the way up. This is a guess of how much the inside flue cools with or without insulated liner, indoor or outdoor chimney........ The first factor is the temperature you're sensing on the outside of pipe is about 1/2 the inside flue gas temp. So 300* is approximately 600 flue gas. This should be enough heat loss up the chimney in a normal situation, excessive chimney height or inner flue diameter requires more heat. It's not the stove, fuel sounds fine, and keeping it hotter prevents creosote buildup. Too much heat left up cuts into heating efficiency. So you have to find the right amount to leave up for the fuel, and heating requirements. (too large of a stove for an area requires slower burning causing problems, so we need to make sure the stove is sized properly. The first post in this thread will identify your stove; https://www.hearth.com/talk/threads/everything-fisher.48309/)
The reason for build up is any fossil fuel creates water vapor during combustion. Wet or wood containing excess moisture compounds the problem. Smoke particles stick to the sides when the water vapor condenses below 250* and can build up rapidly. In the coaling stage this is not a factor.
You should have a stove pipe damper for open door burning, but leave that open until you get the creosote build up manageable. Burning hard woods can get down to one cleaning during the season or at season end only, you will have to go by the norm for the soft woods in your area.
Thanks jatoxico and coaly for all the info sure was helpful. I will have to clean up the inside of stove and sweep chimney and really manage the temp. Need to purchase a pipe temp guage. Coaly should I install that baffle that jatoxico was talking about? My stove pipe comes out the top of stove and would it be better if I necked it down to 6" pipe instead of 8"? That is another problem I have with the stove it is too big for my house and if I burn it hot it gets over 80 degree in the house my house is around 1800sqft and is two story so majority of heat is on the first floor where the stove is.
If you cant run the stove correctly because it is to large you need to get a smaller one. Coaly is right on you need a pipe thermometer to make sure you are running at the right temps also you should run the temp up to 450 or so for 10 to 15 mins every time you load the stove. That will get the chimney heated up and drive off allot of the moisture in the wood.
OK ya I am definitely gonna get one ASAP and really monitor that I'm in the burn zone all the time. I really don't want a smaller stove. So I will have to deal with the heat and open some windows up when it gets too hot. Thanks for your info bholler
Wood to me is free. Woodstoves are not... I really don't burn a hole lot of wood. Only burn for 4 months out of the year I think I can deal with cutting wood and save me money. I keep a small fire during the day then stoke it up at night so I only use about 8 pieces of wood for the hole day with dampers open and at night I can fit about 6 pieces of wood in it and it burns all night long.
Yes but burning that way you have a creosote factory which is just asking for a chimney fire. When you start burning correctly you will go through a llot more wood. And yes you may not pay money for the wood but you put allot of work into it.
jatoxico
Minister of Fire
All the more reason to let more heat up and out to help keep that flue clean. You can also try moving the heat around by gently blowing air into the stove room.
Everything is a balance but given you're needing to sweep often it will be better to burn on the shorter hot fire end of the spectrum rather than the longer low slow type even if you have to deal with bigger temp swings. No downside to adding a baffle. Should help to burn clean and help get closer to what you want.
Check your wood. A moisture meter from Harbor Freight is under $15.
I will get a moisture meter also thanks for that info. I will just have to get the stove set up and run how it's suppose to and see how hot it gets in the house and go from there I may possibly need a smaller stove and I could put the big fisher in the shop...
Another thing to look at is dilution air. Is the clean out door sealed well and inside that clean out is everything sealed up in there? Is the pipe sealed where it goes into the crock?
930dreamer
Burning Hunk
Spotted Owl
Member
I know this is an older thread but I just saw it.
I'm also from Oregon, toward the coast. I've burned the same fuel you have available for years with 100% wood heat only, no other option.
You need to season your wood longer. Hemlock is very wet wood, I season mine for a minimum of two years stacked outside with the sun and wind beating on it, stacked in a barn with no air flow will take 3 plus to get to good burn seasoning. Hemlock is wet heavy wood. Fir is a full year. Alder can be done on the Easter & Fall plan if stacked out side for the sun and heat to beat down on it and for air to blow through the stack, but Alder too, does much better when stacked for a year. Even if you get a newfangled epa stove it won't burn well with the fuel you have to feed it. Everything available in western Oregon just because of the climate and water content of the wood should season for a minimum of a year, two is best, until you get into our oak then it's three to four.
We don't get that cold here. Get the house good and warm in the evening and let the fire go out over night. In the morning start up a good fire and let it run for a while, then settle in and cruise for the day. I run two Papas, a Grandma and a homemade Papa from a fellow Hearthers experienced instructions, built with my boy over the winter a couple years ago.
You might be sure the clean out you have at the back seals up good and isn't sucking cooler than stack temp air into your chimney. Seal up all air leaks into your chimney system, not the stove, the chimney.
Stick with it. There's a bit of a learning curve to burning these stoves that most people don't know or understand anymore. When you get it figured, it'll be worth it and you'll have more heat with your current stove.
Owl
I'm also from Oregon, toward the coast. I've burned the same fuel you have available for years with 100% wood heat only, no other option.
You need to season your wood longer. Hemlock is very wet wood, I season mine for a minimum of two years stacked outside with the sun and wind beating on it, stacked in a barn with no air flow will take 3 plus to get to good burn seasoning. Hemlock is wet heavy wood. Fir is a full year. Alder can be done on the Easter & Fall plan if stacked out side for the sun and heat to beat down on it and for air to blow through the stack, but Alder too, does much better when stacked for a year. Even if you get a newfangled epa stove it won't burn well with the fuel you have to feed it. Everything available in western Oregon just because of the climate and water content of the wood should season for a minimum of a year, two is best, until you get into our oak then it's three to four.
We don't get that cold here. Get the house good and warm in the evening and let the fire go out over night. In the morning start up a good fire and let it run for a while, then settle in and cruise for the day. I run two Papas, a Grandma and a homemade Papa from a fellow Hearthers experienced instructions, built with my boy over the winter a couple years ago.
You might be sure the clean out you have at the back seals up good and isn't sucking cooler than stack temp air into your chimney. Seal up all air leaks into your chimney system, not the stove, the chimney.
Stick with it. There's a bit of a learning curve to burning these stoves that most people don't know or understand anymore. When you get it figured, it'll be worth it and you'll have more heat with your current stove.
Owl
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