Barn Stove questions

[Dpregs]

Hey all. I am looking to install a stove in the barn for occasional burning when I am out there working in the cold weather. It is not a very tight barn and rather drafty. I know where I want to put the stove, but I have a few questions. Here is what I have done so far. My walls are 10 feet high and I put rockwool in the bays behind where the stove is going to go from floor to top of wall, I then put a layer of Durorock. On top of that I put one inch spacers and then another layer of Durorock staggering it 4 inches off the ground. I plan to face the durorock with either stone or manufactured stone. My question is more about the stove. I think I have a old Fisher grandpa stove that was given to me. It is an 8 inch flue, but I have a 6 inch pipe going through the roof. Can I reduce it to a 6 inch pipe up near the top of the run? Here are some pics of what I am working with. Any advice is greatly appreciated

 

[bcrtops]

That stove will need 8" to draw correctly.
Illegal to install in Oregon, not that a few get used in garages etc., anyway.

 

[KDubU]

I was going to ask whether code allows it in CT. If it does, usually it means no machinery that run on fuel can be in the same building.

 

[bholler]

Hey all. I am looking to install a stove in the barn for occasional burning when I am out there working in the cold weather. It is not a very tight barn and rather drafty. I know where I want to put the stove, but I have a few questions. Here is what I have done so far. My walls are 10 feet high and I put rockwool in the bays behind where the stove is going to go from floor to top of wall, I then put a layer of Durorock. On top of that I put one inch spacers and then another layer of Durorock staggering it 4 inches off the ground. I plan to face the durorock with either stone or manufactured stone. My question is more about the stove. I think I have a old Fisher grandpa stove that was given to me. It is an 8 inch flue, but I have a 6 inch pipe going through the roof. Can I reduce it to a 6 inch pipe up near the top of the run? Here are some pics of what I am working with. Any advice is greatly appreciated

View attachment 309753 View attachment 309754 View attachment 309755 View attachment 309756 View attachment 309757 View attachment 309758 View attachment 309759

I see a mower deck as well as a mower or ATV jack in the space. Is the barn used to work on or store vehicles or gas powered equipment?

 

[yooperdave]

By rights, the install you're thinking of has risky written all over it.

It should be in a room by itself.
High risk of fumes getting caught in the combustion air migration to the stove.
The flue should stay 8" all the way. Haven't been able to see just where the 6" goes through the roof; how far away is it?
You did reduce the CTC with the heat shield but, allowing 6" from the floor would be better IMO. Do not close off that floor to heat shield air gap when you finish it off in the future. Personally, I think the heat shield should reflect heat away from it instead of absorbing it like a rock wall would.

That being said, here comes the part where others will disagree with kicking and screaming.

Yes, you can transition from 8" to 6" flue. I did in the past and all worked out well without sacrificing any draft at all. Keep in mind that you do not have a epa stove, allowing for a more forgiving burn. Also keep in mind that by reducing the flue size, you should also adjust your burning habits to match the difference.

But finally and most importantly, is the insurability issue. There are reasons why what you choose to do is not allowed by insurance companies. The choice may just well boil down to you building another garage/barn and replacing all contents-at your expense!

 

[coaly]

Cement board is a good conductor of heat. NFPA 211 Standard is where you will find the criteria for an approved heat shield using a 1 inch ventilated space to combustible wall.

The shield only requires 1 inch open space at bottom, and can be supported on spacers to support weight. The 1 inch wall spacers are only required to be a non-combustible, material, which yours are. The object is the least amount of heat transfer. The contact area of spacers is what transmits heat to wall framing. Pieces of metal tubing, metal nuts, anything with small contact area to prevent transmission of heat is better than cement board. The heat conductivity is high, the airspace does the cooling, not the shield material. The first layer could be Sheetrock, plywood, or any combustible material. The heat shield itself can be anything non-combustible and a minimum of 24 gauge if metal. No spacers within centerline of stove.

Legally the vent cannot be reduced smaller than stove outlet due to the ICC building code adopted by your state. NFPA allowed a1 inch reduction, ICC does not.

The passage through roof must be Class A chimney pipe. Straight up, most physically work reduced to 6. You will not have the maximum btu output if you need it. The smaller diameter reduces the capacity of what the chimney can carry. This reduces the air coming in. These stoves were built with a larger outlet for open door burning, and connecting to a larger existing fireplace chimney. This allowed more heat up the larger chimney reducing creosote formation. So for your application it will probably work fine, limited at full btu output rarely used.

ICC building code also requires all appliances to be UL approved with Label attached for a new installation. This is an unlisted stove. So if insurance becomes an issue, claims could be denied depending on insurance company. Many install and claim the stove was existing, hence the used stove market. When inspections are involved with insured living structures, this prevents unlisted, home made and antiques from being installed.

As others stated, NFPA National Standard does not allow solid fuel burning appliances in garages or where flammable liquids or vapors are present. Many still do, at their own risk. It is not advisable to install in a attached garage that affects the insurance on the living structure.

You will need floor protection as well, normally double cement board with brick or stone covering.

 

[Dpregs]

First, thank you all for the input, way more than I was expecting! Let me give a few more details and possibly answer some of the questions posed.

-This is in a detached 16x32 barn with 10' walls and a peak of ?
-I was intending to exit the roof directly above the stove or run it a little high up the peak using 45s
-I thought the cement board was a heatshield, but I can see from your advice it isn't. I will have to rethink what I face it with. The 1inch spaces are doubled up cement board, but they are short pieces just to hold the screws and don't run the full length of the wall.
-I do keep my tractor in there, but it wouldn't be near the stove when burning. I have seen many people with stoves in their workspaces and thought it would be okay.
-I'll have to check with insurance
-Sounds like it might be a better idea to go with a different stove
-I am only planning on using this on occasion when I need to work out there in the dead of winter. The only combustible...or flammable...is the gas generator stored away from stove and diesel tractor which I would have to move away.


You have given me lots to think about now that I put all that up

 

[coaly]

First, thank you all for the input, way more than I was expecting! Let me give a few more details and possibly answer some of the questions posed.

-This is in a detached 16x32 barn with 10' walls and a peak of ?
-I was intending to exit the roof directly above the stove or run it a little high up the peak using 45s
-I thought the cement board was a heatshield, but I can see from your advice it isn't. I will have to rethink what I face it with. The 1inch spaces are doubled up cement board, but they are short pieces just to hold the screws and don't run the full length of the wall.
-I do keep my tractor in there, but it wouldn't be near the stove when burning. I have seen many people with stoves in their workspaces and thought it would be okay.
-I'll have to check with insurance
-Sounds like it might be a better idea to go with a different stove
-I am only planning on using this on occasion when I need to work out there in the dead of winter. The only combustible...or flammable...is the gas generator stored away from stove and diesel tractor which I would have to move away.


You have given me lots to think about now that I put all that up

Canada allows stoves in garages with vehicular protection with bollards and 18 inch minimum height fire box bottom for heavier flammable vapors below the stove. So that gives you an idea of their safety factors. US goes by NFPA-211 which simply says No garages or where flammable vapors are present.

The cement board an inch away from wall is a heat shield that allows 66% reduction of clearance of 36 inches down to 12 inches minimum.

Over 8 feet of connector pipe should be double wall connector to prevent excessive cooling as flue gas rises to the higher chimney. A chimney support box is normally installed at the 8 door ceiling height, and insulated chimney rises through ceiling, attic, and through roof, preventing cooling from too much single wall pipe. The flue gases have to stay above 250*f to the top where expelled at chimney top. Below this critical temperature, water vapor from combustion condenses on flue walls allowing smoke particles to stick, forming creosote. Yours would be like a cathedral ceiling, which should use double wall connector pipe preventing cooling below this critical temperature.

If reducing to 6, a straight up vent system will likely work without smoke roll in issues. No elbows or other restrictions should be used. Doing that with single wall pipe and that additional height is asking for problems.

Insurance should not cover this for many reasons. They should first be looking for a UL Label. The building code adopted by your state prohibits installation of unlisted appliances. This is only for new installations, but insurance companies can make their own rules and regulations and add the requirement of UL Listed appliances even when existing. If they know what they are looking at, will not allow stove outlet reduction.

 

[Frankdozer]

Canada allows stoves in garages with vehicular protection with bollards and 18 inch minimum height fire box bottom for heavier flammable vapors below the stove. So that gives you an idea of their safety factors. US goes by NFPA-211 which simply says No garages or where flammable vapors are present.

The cement board an inch away from wall is a heat shield that allows 66% reduction of clearance of 36 inches down to 12 inches minimum.

Over 8 feet of connector pipe should be double wall connector to prevent excessive cooling as flue gas rises to the higher chimney. A chimney support box is normally installed at the 8 door ceiling height, and insulated chimney rises through ceiling, attic, and through roof, preventing cooling from too much single wall pipe. The flue gases have to stay above 250*f to the top where expelled at chimney top. Below this critical temperature, water vapor from combustion condenses on flue walls allowing smoke particles to stick, forming creosote. Yours would be like a cathedral ceiling, which should use double wall connector pipe preventing cooling below this critical temperature.

If reducing to 6, a straight up vent system will likely work without smoke roll in issues. No elbows or other restrictions should be used. Doing that with single wall pipe and that additional height is asking for problems.

Insurance should not cover this for many reasons. They should first be looking for a UL Label. The building code adopted by your state prohibits installation of unlisted appliances. This is only for new installations, but insurance companies can make their own rules and regulations and add the requirement of UL Listed appliances even when existing. If they know what they are looking at, will not allow stove outlet reduction.

8 to 6

 

[coaly]

8 to 6

View attachment 309826

That is not a comparison or what I was referring to at all.

What is your chimney diameter, height, and liner type?

 

[bholler]

8 to 6

View attachment 309826

Yes but then into an 8x8 chimney right?

Some people absolutely run them on 6" and it works perfectly fine. Other people end up with poor performance and smoke spillage trying it. I actually find they run best on 7"

 

[Frankdozer]

That is not a comparison or what I was referring to at all.

What is your chimney diameter, height, and liner type?

Oops 😬

 

[Frankdozer]

Yes but then into an 8x8 chimney right?

Some people absolutely run them on 6" and it works perfectly fine. Other people end up with poor performance and smoke spillage trying it. I actually find they run best on 7"

👍😊