# Double-Walled Pipe??



## Whitespider (Oct 8, 2013)

OK, now that the DAKA is installed and running properly I'm tossin' 'round the idea of stickin' the "stovace" out in the shop. I had a barrel stove in there a few years ago; just ran the single wall pipe out a window and up the back wall... was a real PITA to get it drawing from a cold start and the pipe was always plugging with creosote.

So here's the deal... I have zero experience with double-wall.
When my brother's FIL gave me the Pacific Energy Spectrum that I used to make the "stovace" he also gave me 20 feet of double walled pipe (stainless on the inside, I believe the outside is painted steel??). I'm thinkin' the best install is gonna' be to run the pipe straight up, between the rafters and through the roof. What sort of clearances to combustibles (rafters, roof decking and shingles) do I need with double-wall?? How hot does the outside of it get anyway... I mean, does it run cool enough to use a rubber boot to make the weather seal at the roof or can I just use a piece of sheet metal flashing to run the pipe through (sealed with hi-temp silicone)?? I ain't lookin' for pretty, just functional.


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## stihly dan (Oct 8, 2013)

Is it insulated double wall? If so You need 2 inches of clearance. Its not how hot it gets, its how hot it gets when there is a chimney fire. Generally when you have a chimney fire in these, where the fire was has to be replaced. Non insulated will work like crap where you are, But better than your single wall.


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## Bushmans (Oct 8, 2013)

I have double wall insulated and it states that it can be 1.5" away from combustibles. Others are 2"

Sheet metal at the top would be fine I think. I did that at my old place because I didn't want to pay the big price of buying the ready made piece for the roof. 
I'm not sure how hot it gets at the roof but where mine goes through my wall I had the stove up to 400 and I could barely hold my hand on it. Out in the garage where it hit the tee (2.5'away) it was much cooler. I imagine the heat spreads upwards but I am still waiting on some cold weather to get a long burn on my "new" stove.


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## Festus (Oct 8, 2013)

The manufacturer should have installation specs available on their website. Or from a dealers website. If you don't know the exact brand, find one of the same type. I assume you're talking about 6 in ID, 8 in OD. Mine is 6 inch insulated and it still gets pretty hot. You definitely wouldn't want a rubber collar directly around it. I would get the correct type roof collar for the chimney you're using. You do have to caulk around the top trim collar, but the galvanized does most of the work.

This will be my third year with my stove. I just checked the chimney a couple weeks ago and it's still clean. It's black, but there is no soot build up at all. Quite a few birds came down into the stove this spring, and they're not even very dirty when you get them out. With the double wall chimney, you won't get as much heat radiating from the pipe, but the trade off is a helluva good draft. As soon as I get some good flames, I can close the door and open the ash door and I already have a great draft. It's like a turbo charger. With a shorter chimney, I would think you would have less of a draft.


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## Whitespider (Oct 8, 2013)

I have no idea what brand it is... but it ain't anything special.
It's non-insulated and the inner stainless has standard crimped male ends that slip directly into single wall... i.e. you could use standard single-wall pieces interchangeably with it. The outer wall has no type of lock, groove, clip or whatnot... just sheet metal screws to secure it. I won't spend the money for a special pass-through at the roof, I'll just use the sheet-metal flashing thing... after-all, we're talkin' a shop heater that will only be used a few times a year. Heck, I'll likely remove it each spring to get it out'a the way. With a bit of "Googling", I've found that most non-insulated double-wall calls for 6-inch clearance to combustibles... so how the heck is that does that work if the outside diameter is 8-inches and the rafters are spaced 16-inches on center?? Metal shields on spacers??


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## Festus (Oct 8, 2013)

It seems obvious you're talking about stove pipe, and not chimney pipe, hence the 6 inch space to combustibles. 8" OD chimney pipe requires 2". I'm sure you could go less than 6" with a metal heat shield, but I'm not sure your insurance company would like it. Technically, you would have to cut out a section of rafter and frame around the pipe for your clearance. I would think double walled stove pipe would get pretty darn hot. I sure wouldn't put any rubber or caulk on it.


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## Whitespider (Oct 9, 2013)

Hmmmmmm....... yeah, stove pipe.
I didn't say anything about chimney pipe, but I guess I didn't specify stove pipe either.
As far as weather sealing it with high-temperature silicone... the stuff I have says it's good to 1000° (or maybe it's 1200°?) and the label says used for sealing flue pipe and roof flashing (among other things). I'm pretty sure I don't need to worry about double-wall stove pipe getting that hot... especially 8-10 feet above the stove. And even if the pipe got hot enough to cause the silicone to fail, what's the worst that could happen?? Silicone doesn't burn, it vaporizes... and even if it did (or could) burn it's would be a metal-to-metal joint (no combustibles).


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## 1project2many (Oct 9, 2013)

Just some thoughts...

Any piece of metal attached directly to wood will conduct heat to the wood. Metal has an R value of 0. Use air gaps to reduce heat transfer or use products with insulating properties if you want thermal protection.

I'm going through something similar. I'm putting a stove in the barn and the pipe has to run through the pine plank siding. There are no vertical studs to attach a wall box. One plan is to use drain tile or a short piece of chimney tile as a pass though. I'll place fire brick inside and rest the stove pipe on that then add fiberglass insulation around to keep cold air out of the barn. Another is to use "fireboard" and build a pass through box but I have to learn more about the characteristics of said board before going any further with it.

At the end of the day so many people get away with wrong and bad designs that it's hard to justify extra precaution but imo it's all about the one time something unexpected happens. Barns and shops are places where you walk away from the stove, close the door, and forget about what's in the stove. That's when fires seem to take out the building.

The other part of the plan is to only use small pieces of fast burning wood in the stove. It will be a pita to keep filling but when I'm done for the night the fire won't linger for too long.


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## Fred Wright (Oct 9, 2013)

Yep, doublewall stovepipe is typically rated for 6" away from combustibles. And it does make for a nice draft, better than standard smoke pipe.

Our stovepipe is all doublewall, Simpson DuraBlack I believe. Exits the stove, 4' up then 90° for a couple feet to the thimble. The pipe is too hot to touch where it exits the stove. However, it's only slightly warm at the thimble connection.

I don't recommend going under the 6" rating... but you might get away with it since the pipe will be fairly cool to the touch at roof height.


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## Mr Good Wood (Oct 9, 2013)

how high is ceiling in shop? run single black from stove to 2 foot from sheet metal ceiling get a double insulated t through wall then get double insulated pipe outside just enough to clear roof then use the double no ins. that u have to get as high as u need above peak. the single wall will give more heat off in building and the as long as u put cement board on wall your fine. my single wall inside 6 inch from wall and i can hold my hand on back of cement board indefinitely no matter how big the fire. use the orange foam to seal between t and hole in side wall. i think it be tougher to get a good seal at roof vs sidewall mount. 10yea and running and no leaks and crazy good draft and hardly ever clean, no need to we look in it and nothing. 3 cord a year average.


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## stihly dan (Oct 9, 2013)

Spidey, its not the heat. Its the heat if there is ever a chimney fire. That 6 inches is at 2100 *. If your like me? There is 10X the money in the shop than in the house.


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## Whitespider (Oct 10, 2013)

Mr Good Wood said:


> *how high is ceiling in shop? run single black from stove to 2 foot from sheet metal ceiling get a double insulated t through wall then get double insulated pipe outside just enough to clear roof then use the double no ins. that u have to get as high as u need above peak. the single wall will give more heat off in building and the as long as u put cement board on wall your fine...*



Well, you're sort'a missing the point. I already have 20 foot of stainless double-wall (with rain/varmint cap) and a top exhaust stove... and I'm trying to avoid elbows and outside-up-the-wall pipe to minimize draft issues. Besides, insulated pipe, elbows, tees and whatnot ain't cheap.

The "shop" is just a two-stall garage with so much of my "shop stuff" ya' can't park a vehicle in it any more. It has an open ceiling, but the horizontal stringers are about 7½ foot above the floor. The roof, where I'm plannin' to set the stove, is about 2 foot above the stringers. I'm plannin' to set the stove up on blocks, and with top exhaust there'll only be about 5-6 foot or so of pipe inside the building... at most, I could only use 2 foot of single-wall before running into clearance problems at the stringers. Clearances to walls won't be an issue... the stove will sit some 3-4 foot away from any wall.

Actually, using the double-wall stove pipe, figuring 6 inches clearance, I won't have any problems. I was thinking the rafters (and stringers) were 16 inches on center, but they're not, they're 24... at 22 inches from board face-to-board face I'll have 7 inches clearance. I'll cut a 22 inch circle in the roof, use sheet metal flashing, seal the pipe with high-temp silicone, make (or buy) a sheet metal storm collar (also sealed with high-temp silicone), and I'll have an extra inch of clearance everywhere. Just 12 foot of pipe should put me well above the peak and I can brace/support the pipe inside at the stringers (i.e. shouldn't need any supports outside).

No fuss, no muss... and best of all, no cost (unless I buy, rather than make, the storm collar... 8-bucks at the fleet store).


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## haveawoody (Oct 10, 2013)

Whitespider,

What has the original length of pipe you had on the original setup?
Creosote and hard to start sound like short pipe for the chimney effect or the shop is to air tight.

Best way to do it is to go straight up if you can, any elbow will decrease the chimney effect and add to creosote amounts so maybe original setup is a combo of things.
Or it could be just the barrel stove wasn't much to write home about and was a poor burner.


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## woodfarmer (Oct 10, 2013)

Never ever ever use double wall flue pipe to go through a wall or ceiling, but it sounds like you've made up your mind to use it anyway so why ask for advice.
You should be using insulated stainless steel chimney.


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## Whitespider (Oct 10, 2013)

woodfarmer said:


> *Never ever ever use double wall flue pipe to go through a wall or ceiling, but it sounds like you've made up your mind to use it anyway so why ask for advice.
> You should be using insulated stainless steel chimney.*



Really?? Who says??

This is the same pipe used to install the same stove in my brother's FIL's home and it ran straight up and through the ceiling/flat roof in his family room. It was installed professionally, by the company who sold him the stove, and to code (in town code, not out in the county). They did not use insulated pipe to pass through the roof... just a sheet metal flashing pass-through with a storm collar. Also, my dad's double-wall stove pipe is installed (professionally) in the exact same way in his cathedral ceiling log home... no insulated pipe at the pass-through, just metal flashing with a black-painted metal trim box.

The way I understand it... insulated is used to pass through finished drywall (walls or ceilings) so as to minimize the size of the hole cut in it, but isn't mandatory if you don't mind the larger hole and unsightly metal.


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## Whitespider (Oct 10, 2013)

Something else y'all need to consider when stating what you believe is "code" and such...
This ain't a residential building... it ain't attached to a residential building... it's located outside any municipality... "codes" for residential/family dwellings do not apply.


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## Whitespider (Oct 10, 2013)

haveawoody said:


> *What has the original length of pipe you had on the original setup?
> Creosote and hard to start sound like short pipe...
> Best way to do it is to go straight up if you can...*



The reason I had poor draft with the barrel stove was because it was a slam-be-damned install. Started with a 16 inch pipe vertically off the barrel, a 90° elbow out a window opening, another 90° elbow outside, and 12 foot of pipe up the outside wall and above the peak... all of it single-wall. It flat lost all the heat before flue gasses could exit. I knew it was gonna' work like sour owl crap when I installed it... but hey, it was -10° when I did it, I was just lookin' for some heat in the shop. It worked sort'a OK once everything got good and hot... if'n ya' didn't mind breathing a little smoke while workin' in there. I'd pull the barrel out every spring (left the pipe in place), slam the barrel back in the fall... one spring the barrel collapsed during the move and I never replaced it.

So anyway, now I have the Spectrum ("stovace") and I figure... why not? And yeah, I'll run the pipe straight up (using double-wall and no elbows), while keeping at least half of it inside... I'm figuring it will work much better that way. Does it have to be perfect?? Heck no... it's a drafty old building (you can see light through the cracks and around the overhead doors), I just wanna' knock the chill off on those really cold days I need, or want to be out there working. Sometimes I just wanna' escape the house for a few hours...


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## haveawoody (Oct 11, 2013)

Whitespider,

Ah a darn I'm cold install LOL

I'm sure the stove from downstairs will work like a champ.
I'm of the same mind if it can be used why not.
Like you say it's nice to be warm while working in the place and a great place to escape for a bit.

Once you have it working I see man cave in the future


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## Whitespider (Oct 12, 2013)

Interesting...
I've been doin' some reading, the 2013 and 2012 National Fire Codes do specify Class A Chimney for a roof pass-through and outside (I haven't looked back further than that) for single family dwellings. Obviously my brother's FIL's install, and my dad's, was done before that became part of the code... dad's was done at least 45 years ago. The reasoning, as I'm reading it, is not because of the pipe surface temperature... rather the internal temperature. The reasoning it to keep the flue gasses warm, the draft strong, and thereby reduce creosote formation... which, in turn, reduces the chances of a chimney fire.

Well, in any event, this building ain't a "dwelling"...
Man, I could drive you around this area and show you at least a dozen black stove pipes poking through roofs, walls and windows before we could finish a 6-pack. I guess we just like to live dangerously out here in hickville.


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## AIM (Oct 13, 2013)

The National fire code was updated/revamped just a few years ago. To what extent I really don't know.
I was installing a exhaust hood at a carryout and the asst fire chief was telling me that things had changed quite a bit with the nfc. I really can't remember when he said the changes happened but 2005 comes to mind.

In your case though. Who cares what the nfc wants. I know I wouldn't.


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## Whitespider (Oct 13, 2013)

AIM said:


> *In your case though. Who cares what the nfc wants. I know I wouldn't.*



L-O-L I'm really "liking" that!!


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## AIM (Oct 13, 2013)

The NFC and other building codes are a very good thing when I am building something for others or something public etc. For myself I build/install how I want. I am not concerned about codes.
I'll bet you aren't either.


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## Whitespider (Oct 13, 2013)

Nope, I couldn't care any less about "codes".
Most of the time they're designed to protect us from ourselves... and if your head is in the game there ain't no need. The idea that one "code" fits all situations and circumstances is beyond ridiculous... flies in the face of common sense. Rather than move firewood today I installed the stove in the shop because it was a perfect day to be on a roof (i.e. no wind), and I did it "my way".


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## dustytools (Oct 13, 2013)

My old barrel stove has bitten the dust too. Im gonna take the old VC smoke dragon down to the shop to replace it. Nothing like a warm shop when you need to get out of the house awhile.


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## philoshop (Oct 13, 2013)

Glad you got the pipe in and I'm sure your own common sense was your guide.
As to the issue of 'codes', it seems that an awful lot of people these days need to be protected from themselves, and a lot of 'the code' is there to protect the innocent from the misguided. When structures fail people tend to get hurt. Friends, neighbors, first responders, children.
Most people know it's not a good idea to drive 80 mph down a residential street, but some would see no problem at all with that. Hence, we have the 'code' that is the speed limit.
Common sense takes some thinking. Thinking can be work. That's why you don't see more of it. Just sayin'.
Best,
Philo


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## Whitespider (Oct 14, 2013)

Well, I went with 7 inches of clearance for the pipe, and used heavy gauge steel flashing through the roof. The stove (or stovace) manual calls for 4 inches clearance in a "corner" install, I have 18 inches. I went ahead and left the steel plenum, or air jacket, that I built and mounted one of the blowers from the DAKA so I'm able to blow warm air across the shop. Originally I planned to set the stove on blocks but after some measuring I didn't. Those pipe sections were 4 feet, and with the stove directly on the floor three sections put the top right close to 2 feet above the peak... with only about 5 feet exposed to the outdoors.

OK, so I didn't use class A chimney through the roof... but I do plan on keeping the thing clean. Just 12 feet of double-wall pipe, straight up, should draft one-heck-of-a-lot better than the single-wall out the window did for the barrel. The high-temp silicone at the flashing should be cured tonight when I get home... maybe a test fire??


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