Help. In need of advice.

[Robert5]

We have an old Kodiak wood burning stove. It is quite lsrge.
We use it to heat our livingroom, kitchen, dining room and a tiny office.
Total is a 650 sq. Feet.
the trouble we are running into is that in order to not make it a sauna there, we have to run it well below a normal fire box temperture.
the result is so much creosote that it results in a need for a chimney cleaning every 30 days or a chimney fire will occur.
this is an on going problem. I need to solve this.
I should also explain that the pipe is on the back of the stove not the top. It comes out and runs horizontal for about 2-3 feet through what was a fireplace and then turns vertical and goes up to a very tall chimney. The vertical part is ( I don't know what you call it ) sort of a flexible steel rectangular type of pipe (looks like an accordion).
Most of the creosote seems to form in the horizontal pipe.
We burn only aged hard wood.
I hope someone on here knows what the true problem is and how to fix this issue. Currently we are considering getting a much smaller stove and getting rid of the old Kodiak stove. But honestly i don't know if we are on the right track.

 

[begreen]

Welcome. You are on the right track. Getting rid of the horizontal run will help as will switching to a cleaner burning insert or stove more properly sized to the area being heated. Is the wood stove the only source of heat or is there another source for milder weather when temps outside are above 50º? Depending on the firebox size in the fireplace either a modern insert should solve the problem. If the fireplace opening is tall enough then a freestanding stove might also work.

 

[bholler]

We have an old Kodiak wood burning stove. It is quite lsrge.
We use it to heat our livingroom, kitchen, dining room and a tiny office.
Total is a 650 sq. Feet.
the trouble we are running into is that in order to not make it a sauna there, we have to run it well below a normal fire box temperture.
the result is so much creosote that it results in a need for a chimney cleaning every 30 days or a chimney fire will occur.
this is an on going problem. I need to solve this.
I should also explain that the pipe is on the back of the stove not the top. It comes out and runs horizontal for about 2-3 feet through what was a fireplace and then turns vertical and goes up to a very tall chimney. The vertical part is ( I don't know what you call it ) sort of a flexible steel rectangular type of pipe (looks like an accordion).
Most of the creosote seems to form in the horizontal pipe.
We burn only aged hard wood.
I hope someone on here knows what the true problem is and how to fix this issue. Currently we are considering getting a much smaller stove and getting rid of the old Kodiak stove. But honestly i don't know if we are on the right track.

The problem is you have an old stove that even when burnt at proper temps doesn't burn cleanly. Then you have it in a space that is about 1/3 the size it is meant to heat. There is very little chance that the stove you have will ever be able to perform well in your space. Start looking at different stoves.

What moisture content is your wood at? If you don't know that how long has it been cut split and covered before burning?

 

[Robert5]

Welcome. You are on the right track. Getting rid of the horizontal run will help as will switching to a cleaner burning insert or stove more properly sized to the area being heated. Is the wood stove the only source of heat or is there another source for milder weather when temps outside are above 50º? Depending on the firebox size in the fireplace either a modern insert should solve the problem. If the fireplace opening is tall enough then a freestanding stove might also work.

Yes, the wood stove is the only source of heat for those rooms.
Thanks for the reply.

 

[Robert5]

The problem is you have an old stove that even when burnt at proper temps doesn't burn cleanly. Then you have it in a space that is about 1/3 the size it is meant to heat. There is very little chance that the stove you have will ever be able to perform well in your space. Start looking at different stoves.

What moisture content is your wood at? If you don't know that how long has it been cut split and covered before burning?

thank you for taking the time to answer. Much appreciated.
don't known the moisture content but most of the heating season the wood is aged roughly 12 months.
I do fear you are correct that the old stove has to go. A new stove and a smaller stove hopefully is the answer.

 

[bholler]

thank you for taking the time to answer. Much appreciated.
don't known the moisture content but most of the heating season the wood is aged roughly 12 months.
I do fear you are correct that the old stove has to go. A new stove and a smaller stove hopefully is the answer.

There is a good possibility your wood still has too much moisture in it as well. It is possible to get hardwoods below 20% in 12 months but only split small and in optimal conditions.

 

[Robert5]

So, the wood can also be part of the problem.
the wood is generally 12 mo. old. It's covered with a tarp. But as our winter goes on, a ton of snow gets on the tarp covered wood. The snow and ice melts and freezes and some of the wood does get wet. We do our best to bring wood inside and have it dry out again for 3-4 days before it is used.a
funny thing, I remember this not being this big of a problem 3-4 years ago. Same stove, same process for wood storage and same usage.

 

[gzecc]

The exterior water on the wood is not the problem. The wood seasons inside. Unless it pine, poplar or ash, 1 year split is not enough. Get a cheap moisture meter on line, split a few pieces open and see where you re at.

 

[Robert5]

Gzecc

I will look for that moisture meter.
Thank you much.

 

[begreen]

Gzecc

I will look for that moisture meter.
Thank you much.

General makes a decent unit for under $25. To test, resplit the wood and test on the freshly exposed face of the wood at about 72º.

What species of wood do you generally burn?

 

[Robert5]

I have ordered a moisture meter.
Wood mix: Oak, Birch, Beech, Ash. The largest content being Oak.

 

[begreen]

Oak is going to be the slowest to dry. It typically takes a couple years to season. Ash and birch can dry in a year under good conditions.

 

[gzecc]

The oak residue is what your probably scoping off your pipes. I think fresh oak takes three years, split and stacked to get to 20%.
Stay away from oak. Load up on birch and ash is possible.

 

[Robert5]

I'll have to talk to my wood supplier and see if there is any choice to be had.
Not sure if that's an option or not. I get it split and delivered which is normal around here and the price is good. $225 per cord.

 

[Robert5]

Oak is going to be the slowest to dry. It typically takes a couple years to season. Ash and birch can dry in a year under good conditions.

Good to know. Thanks for the info.

 

[coaly]

Are you closing a flue pipe damper or using a pipe thermometer?

 

[Robert5]

Are you closing a flue pipe damper or using a pipe thermometer?

We do use a flue pipe damper. We used to keep in open very little once the fire was burning well. But then we started leaving it mostly open in an effort to burn the stove hotter.

 

[coaly]

We do use a flue pipe damper. We used to keep in open very little once the fire was burning well. But then we started leaving it mostly open in an effort to burn the stove hotter.

So you know what causes the creosote build up and why, here's a quick explanation;

Water vapor from combustion condenses below 250*f. in the pipe or chimney. This allows the flue liner or connector pipe to get wet inside which allows smoke particles to stick. This is creosote. So the object is keeping the inner flue temp above 250* to the top when smoke is present.

Moisture in or on wood increases the water vapor, but any combustion of fossil fuels creates water vapor when burned.
The flue damper is a chimney control that slows the velocity of rising gasses. This reduces the draft in an over drafting chimney, and increases dwell time the smoke particles are in chimney, giving them more time to stick. It is a chimney control that affects the stove by slowing not only exhaust, but intake air as well.

The magnetic surface mount thermometer will show about 1/2 the actual inside flue gas temp. The colored zones on it are a guide to show what temp would be exhausted at the top of an average chimney. They are made to use on single wall pipe, not stove top for creosote prevention. Without one, you're guessing. Insulating the liner stays hotter, so the only way to know what temp you have at the top is with an IR thermometer aimed a foot or so down the side of flue at top. You then know how hot you're running by the temp gauge at the bottom. You need to see if the chimney flue liner is insulated. A smaller stove, or new one that has much less heat loss may require it as it cools going very high. A higher chimney creates more draft, but also requires more heat. New smaller stoves with fiberboard baffles have a hotter running top than the exhaust coming out of the stove. So they need a more efficient chimney.

This is why sizing the stove is important. You need to keep the chimney hot enough to stay clean, which means bringing the chimney up to temp every fire. BTU output goes by the temp of each square inch of radiating surface area of the stove. So the more surface area, the lower you need the surface temps. You can't satisfy the chimney needs running the stove too cool.

If you wanted to burn smaller fires with the larger stove, a double wall pipe stays hotter inside with less cooling of the inner pipe, and insulating what sounds like a flexible liner raises inner flue temp so the smaller fire has enough heat loss up the stack to stay clean.

 

[Robert5]

So you know what causes the creosote build up and why, here's a quick explanation;

Water vapor from combustion condenses below 250*f. in the pipe or chimney. This allows the flue liner or connector pipe to get wet inside which allows smoke particles to stick. This is creosote. So the object is keeping the inner flue temp above 250* to the top when smoke is present.

Moisture in or on wood increases the water vapor, but any combustion of fossil fuels creates water vapor when burned.
The flue damper is a chimney control that slows the velocity of rising gasses. This reduces the draft in an over drafting chimney, and increases dwell time the smoke particles are in chimney, giving them more time to stick. It is a chimney control that affects the stove by slowing not only exhaust, but intake air as well.

The magnetic surface mount thermometer will show about 1/2 the actual inside flue gas temp. The colored zones on it are a guide to show what temp would be exhausted at the top of an average chimney. They are made to use on single wall pipe, not stove top for creosote prevention. Without one, you're guessing. Insulating the liner stays hotter, so the only way to know what temp you have at the top is with an IR thermometer aimed a foot or so down the side of flue at top. You then know how hot you're running by the temp gauge at the bottom. You need to see if the chimney flue liner is insulated. A smaller stove, or new one that has much less heat loss may require it as it cools going very high. A higher chimney creates more draft, but also requires more heat. New smaller stoves with fiberboard baffles have a hotter running top than the exhaust coming out of the stove. So they need a more efficient chimney.

This is why sizing the stove is important. You need to keep the chimney hot enough to stay clean, which means bringing the chimney up to temp every fire. BTU output goes by the temp of each square inch of radiating surface area of the stove. So the more surface area, the lower you need the surface temps. You can't satisfy the chimney needs running the stove too cool.

If you wanted to burn smaller fires with the larger stove, a double wall pipe stays hotter inside with less cooling of the inner pipe, and insulating what sounds like a flexible liner raises inner flue temp so the smaller fire has enough heat loss up the stack to stay clean.

Fantastic description and explanation. Thank you.
Giving what you know of my situation, what would you do?
I should mention that any steps I can actually take are very budget driven. We can do a new stove if it is inexpensive. And we would need the old stove removed ( approx. 500 lbs) and the new stove installed.

thanks all for the advice

 

[blades]

Accordian steel liner in flue -doubt that is insulated, but possible. Running that horizontal pipe at an up angle to the flue junction would help if possible. Now I do not know the Kodiak stove personally, but all stoves have a recommended flue area cross section and it is possible that your flue is too large in cross section to maintain a proper flow / heat relationship. Not particularly budget friendly but I would start with the flue ( note most new stoves with the exception of the BK King and one or two others) only require a 6" dia. flue - or roughly 28 sq inches that rectangular flue is likely double that or more. Another point is those accordion pleats add surface area so more places for creosote to stick and impeding the flow depending on how well it is stretched out.

 

[bholler]

Accordian steel liner in flue -doubt that is insulated, but possible. Running that horizontal pipe at an up angle to the flue junction would help if possible. Now I do not know the Kodiak stove personally, but all stoves have a recommended flue area cross section and it is possible that your flue is too large in cross section to maintain a proper flow / heat relationship. Not particularly budget friendly but I would start with the flue ( note most new stoves with the exception of the BK King and one or two others) only require a 6" dia. flue - or roughly 28 sq inches that rectangular flue is likely double that or more. Another point is those accordion pleats add surface area so more places for creosote to stick and impeding the flow depending on how well it is stretched out.

Why would you assume a stainless liner is uninsulated? Many are. And stretching a flexible liner doesn't smooth it out at all. Most kodiaks are 8" vent as well

 

[gzecc]

The exterior water on the wood is not the problem. The wood seasons inside. Unless it pine, poplar or ash, 1 year split is not enough. Get a cheap moisture meter on line, split a few pieces open and see where you re at.

The oak residue is what your probably scoping off your pipes. I think fresh oak takes three years, split and stacked to get to 20%.
Stay away from oak. Load up on birch and ash is possible.

"The oak residue is probably what you're scraping off your pipes"
Sorry for the typo's above. I'm on pain killers and muscle relaxers because of a back injury.

 

[Robert5]

I knew what you meant.
Hope you heal quickly.