# Figuring a class A wall exit chimney for my shop.



## Shaggyant (Jan 30, 2016)

Long story short. I got a free stove for my new pole barn shop. It's a huge old Hurricane stove and it's got big double doors on it and a 10" flue collar.

That's the problem I'm having. A 10" flue collar is kind of a bastard size. It's $1100 for just the clean out tee alone...
https://www.northlineexpress.com/10-duratech-stainless-steel-tee-with-cap-10dt-tss-7248.html

Can I use a normal 6" class chimney kit? It's smaller but it's kind of the current standard and it would be way cheaper. Will it work fine? Seems like it's what most people are using.

Is the reduction in flue size going to kill the output of the stove? I need output to heat my 1700 square foot pole barn with 14' walls.


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## begreen (Jan 30, 2016)

No, you need to stick with 10" chimney. The chimney should match the flue collar diameter. Maybe sell the Hurricane and find something that will work with 6"?


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## Shaggyant (Jan 30, 2016)

begreen said:


> No, you need to stick with 10" chimney. The chimney should match the flue collar diameter. Maybe sell the Hurricane and find something that will work with 6"?



 Any reasoning or explanation for this? I could torch the 10" collar and fab up a 6" one if it's simply the collar size. They also make reducers. 

 What about an 8" chimney? That would still be somewhat affordable.


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## begreen (Jan 30, 2016)

It's the volume of air that the Hurricane needs. A 6" collar would probably lead to puffbacks and a lot of smoke spillage.


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## Shaggyant (Jan 30, 2016)

begreen said:


> It's the volume of air that the Hurricane needs. A 6" collar would probably lead to puffbacks and a lot of smoke spillage.



How does a 6" collar factory stove avoid this?
 When people build their own stoves how do they calculate flue collar size for proper operation?


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## bholler (Jan 30, 2016)

Shaggyant said:


> When people build their own stoves how do they calculate flue collar size for proper operation?


Many times they do not figure anything and many times their stoves do not work well at all


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## Shaggyant (Jan 30, 2016)

bholler said:


> Many times they do not figure anything and many times their stoves do not work well at all



Well, I did some research but I need to see what kind of chart I can find for the 10" pipe...



> it all depends on the height of your chimney. The height of the chimney has a direct effect on it's capacity. A chart from the 1981 copy of "Wood Heat Safety" by Jay W. Shelton, shows the following ratings for a chimney.
> 
> Height----6" Chimney----------7" Chimney----------------8" Chimney
> in Feet
> ...


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## bholler (Jan 31, 2016)

Shaggyant said:


> Well, I did some research but I need to see what kind of chart I can find for the 10" pipe...


Yes but how many btus does that stove put out?  That is a very basic rule.  The size of the vent mainly depends on the size of the firebox and the size of the air inlets.  You need to maintain the proper ratio there.


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## begreen (Jan 31, 2016)

A very large stove, furnace or fireplace needs to move a larger volume of air. If you went straight up and out the roof the Hurricane might work with 8" or it might not. See if you can find out more information on this stove or a manual. Some make an exception depending on how it's used. For sure adding two 90º turns in the smoke path is going to add resistance that will slow down draft. With a wall exit I would not downsize the factory flue.


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## Shaggyant (Jan 31, 2016)

begreen said:


> A very large stove, furnace or fireplace needs to move a larger volume of air. If you went straight up and out the roof the Hurricane might work with 8" or it might not. See if you can find out more information on this stove or a manual. Some make an exception depending on how it's used. For sure adding two 90º turns in the smoke path is going to add resistance that will slow down draft. With a wall exit I would not downsize the factory flue.



 I was thinking maybe an 8" straight up the 20' I need to exit the shop at the peak may be just the ticket. 

 I really hate the idea of poking a hole in my unmolested and immaculate steel roofing for a chimney but it may be the only way. It would save considerable money since I'd only need a short section of class A at the roof penetration and the rest could be some cheap single wall stove pipe.


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## bholler (Jan 31, 2016)

Shaggyant said:


> I was thinking maybe an 8" straight up the 20' I need to exit the shop at the peak may be just the ticket.
> 
> I really hate the idea of poking a hole in my unmolested and immaculate steel roofing for a chimney but it may be the only way. It would save considerable money since I'd only need a short section of class A at the roof penetration and the rest could be some cheap single wall stove pipe.



I think straight up 20' would probably work ok with 8"  But i would at least run double wall inside to keep the stack temps up better if most of that 20' is going to be pipe not chimney.


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## Shaggyant (Feb 2, 2016)

bholler said:


> I think straight up 20' would probably work ok with 8"  But i would at least run double wall inside to keep the stack temps up better if most of that 20' is going to be pipe not chimney.



No reason to run $$ class A chimney until I hit the roof. A single 48" piece should be fine since the pole barn roof trusses are 12 feet apart. I can maintain a three foot clearance pretty easily.
Any reason not to run stove pipe all the way up to the roof penetration? It's way cheaper and I have plenty of clearance. I could even run 10" single wall up to keep it 10" until I hit the 48" piece of chimney.

It's proving extremely difficult to find parts in the 10" variety. I haven't found a roof penetration that would even work for that large of a chimney.  You have to think that a 10" pipe has a 78.54 square inch cross section. That's HUGE! Way bigger than the two draft inlet screw things on the front . Could you imagine how quick this thing would overfire with that kind of draft if the door was open a crack?


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## bholler (Feb 2, 2016)

Shaggyant said:


> Any reason not to run stove pipe all the way up to the roof penetration?


I am talking about stove pipe not chimney pipe.  But I am referring to double wall pipe instead of singe wall in order to keep up the stack temp to maintain draft and reduce creosote buildup.


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## begreen (Feb 2, 2016)

The double-wall stove (connector) pipe will be more expensive than single-wall stove pipe, but less expensive than the 10" plan because it will be 8".


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## Shaggyant (Feb 2, 2016)

bholler said:


> I am talking about stove pipe not chimney pipe.  But I am referring to double wall pipe instead of singe wall in order to keep up the stack temp to maintain draft and reduce creosote buildup.





begreen said:


> The double-wall stove (connector) pipe will be more expensive than single-wall stove pipe, but less expensive than the 10" plan because it will be 8".



 So are we saying to use 8" double wall stove pipe over 10" single wall stove pipe? I'm getting confused here because a few posts back I was getting told 8" is a no go and now it's the recommended size? I'm thinking 8" is going to be the only reasonable prices way to penetrate the roof.

  The problem with a 10" is to do a 20' tall class A chimney out the wall would be like $5k plus. That's just not in the cards and the only way I've found parts to do that is through the wall. I haven't found a roof flashing for a triple wall 10" ID pipe. The triple wall is like 15" OD.


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## bholler (Feb 2, 2016)

Shaggyant said:


> So are we saying to use 8" double wall stove pipe over 10" single wall stove pipe?



No 10" would still be preferred but If you run 8" double wall straight up from the stove and out it will probably work ok.  



Shaggyant said:


> I haven't found a roof flashing for a triple wall 10" ID pipe.


Well you don't want triple wall you want insulated double wall chimney and if they make the pipe they make the flashing call some companies they will make it if they don't have it in stock.


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## Shaggyant (Feb 2, 2016)

bholler said:


> No 10" would still be preferred but If you run 8" double wall straight up from the stove and out it will probably work ok.
> 
> 
> Well you don't want triple wall you want insulated double wall chimney and if they make the pipe they make the flashing call some companies they will make it if they don't have it in stock.



So you are saying go 18' of single wall 10" and then poke through the roof with a 48" piece of chimney at the 20' peak?


 Problem is I need a flashing for a corrugated metal roof in 10" ID. like the Excel flashing or the Dektite.


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## bholler (Feb 2, 2016)

Shaggyant said:


> So you are saying go 18' of single wall 10" and then poke through the roof with a 48" piece of chimney at the 20' peak?


Well I still would not recommend 18' of single wall stove pipe but it would probably work after you finally got it to draw.  I regularly just use plain old metal flashing on corrugated metal roofing i cut it so i can slide the top of the flashing up under the roof and then seal with rubber


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## Shaggyant (Feb 2, 2016)

bholler said:


> Well I still would not recommend 18' of single wall stove pipe but it would probably work after you finally got it to draw.  I regularly just use plain old metal flashing on corrugated metal roofing i cut it so i can slide the top of the flashing up under the roof and then seal with rubber



https://www.northlineexpress.com/10-duratech-0-12-6-12-adjustable-roof-flashing-10dt-f6-7239.html

This is the flashing I can find for 10".

 Do you know of any 10" double wall stove pipe that isn't class A rated and $150 a foot? I am thinking a good double wall 8" stove pipe up to the ceiling and then a stub of 8" class A thought the roof with an Excel flashing on the top side.

 I am just not seeing how 20' of insulated double wall stove pipe in 8" won't be as good or better than single wall 10" stove pipe. Being in a shop it's going to be doing a lot of starting a fire from dead cold. Not really an application where I can just keep feeding the fire 24/7 so it doesn't cool down and lose draft.


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## bholler (Feb 2, 2016)

Call up some chimney supply places and get quotes.  I know for a fact that we can get 10" double wall pipe and flashing ect from olympia.  I doubt they would have it all in stock so we would have to wait for them to make it but i am positive it is available from other places as well.  You could also just get a different stove that is meant to run on 8" or 6" chimney


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## Shaggyant (Feb 2, 2016)

bholler said:


> Call up some chimney supply places and get quotes.  I know for a fact that we can get 10" double wall pipe and flashing ect from olympia.  I doubt they would have it all in stock so we would have to wait for them to make it but i am positive it is available from other places as well.  You could also just get a different stove that is meant to run on 8" or 6" chimney



What stove has a 6" flue collar and can heat 1728 square feet and 29,376 cubic feet of poorly insulated garage?
I pretty much need a nuke in a box to keep this place warm. I've tried a pellet stove (Whitfield advantage II (48,000 BTU I think)) in my last shop that was half this size (34x30) and it was a miserable failure.


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## bholler (Feb 3, 2016)

Well personally i would spend some time and money on insulation and go with an old fisher or alaska or something like that.  Some of the big old stoves like that would probably heat your place but it will do much better if you insulate.  And you wont have to cut nearly as much wood.  and yeah unless it is insulated well a pellet stove wont do that sized shop.  We heat our 24x40 with pellets usually about 1/2 to 3/4 bags a day.  But it has 3" of foam on the outside of the block walls going 3'down into the ground and then 4" in the ceiling.  All of that is foamed and taped together .  You would not have to go to that extreme but every little bit helps.


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## begreen (Feb 3, 2016)

Please re-read the complete thread. The option for 8" was given for only one condition, a straight-up venting with adequate chimney for draft. This was answered to the repeated questions whether the stove could be run on smaller pipe. Both 10" and 8" chimney pipe and connector pipe are available. Here is a link for one vendor:
http://www.woodstovepro.com/store/Chimney-Pipe-Venting-Pipe/Wood-All-Fuel-Piping/10-inch-c204/


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## Shaggyant (Feb 3, 2016)

begreen said:


> Please re-read the complete thread. The option for 8" was given for only one condition, a straight-up venting with adequate chimney for draft. This was answered to the repeated questions whether the stove could be run on smaller pipe. Both 10" and 8" chimney pipe and connector pipe are available. Here is a link for one vendor:
> http://www.woodstovepro.com/store/Chimney-Pipe-Venting-Pipe/Wood-All-Fuel-Piping/10-inch-c204/



I've got all that. I was just questioning the use of a 10" single wall stovepipe 20' tall straight up vs an 8" double wall stovepipe 20' tall straight up. Both choices were roughly the same cost. I gathered that an 8" insulated would be better. If I'm running straight up wouldn't stove pipe be way cheaper than Class A seeing as I'll have plenty of clearance if I'm going straight up through the roof.

Hey! That site has better prices on 10" than what I was seeing at the other couple of sites I was looking at.


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## bholler (Feb 3, 2016)

For an 18' run of pipe i would personally use double wall pipe regardless


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