Why can't stove pipe be used as a chimney?

[gapman789]

Hey everyone. I've been searching and reading all I can for tips and instruction on how to install a wood burning stove in my 24' x 30' detached garage.
I have a good size AURORA stove.

My plans are to keep the stove 5-6 ft from the back wall.
I was going to put a '90' on the back of the stove and then put a 4-5 ft. section of black pipe. Then another '90' and run a few more feet of stove pipe that I will connect to some double or triple wall pipe to go thru the CELOTEX wall and wood siding , which make up my garage walls.
Once I'm outside the garage about 2-3 ft., I was going to run black stove pipe straight up about 10-12 ft to get past the peak of the roof.

Can I not use stove pipe as my chimney, with a cap/rain shield on top of it?

Also, could I not just run the double wall pipe thru the wall and let it extend a few feet on the outsdie and turn it upward for 1-2 ft and be done with it, instead of running a stack/chimney all the way up?

Thanks

 

[jotulguy]

#1 clearances #2 you need that heat in the pipe so you arent forming creosote. The flue would cool too fast and only cause you issues down the road.....high risk of chimney fires!

 

[corey21]

#1 clearances #2 you need that heat in the pipe so you arent forming creosote. The flue would cool too fast and only cause you issues down the road.....high risk of chimney fires!

Agreed your system will not get enough heat draft would be poor and a ton of creosote.

 

[SteveKG]

Once I'm outside the garage about 2-3 ft., I was going to run black stove pipe straight up about 10-12 ft to get past the peak of the roof.

Can I not use stove pipe as my chimney, with a cap/rain shield on top of it?

Also, could I not just run the double wall pipe thru the wall and let it extend a few feet on the outsdie and turn it upward for 1-2 ft and be done with it, instead of running a stack/chimney all the way up?

Thanks

If I am picturing this correctly, your stove pipe would end at or just above the eve of the roof??? I mean, if you ran it up only a couple feet after the elbow. This is bad news. For one thing, there is the distinct possibility of emitting embers or sparks right there at roof level. For another, any wind/air movement [atmospheric] will wreck havoc with back/down drafting. The pipe needs to go higher, period. It should be higher by a few feet than the top of the roof.

You can use regular stovepipe for this. The problem is, as someone said, the exhaust being too cool and the formation of crud inside the pipe [because the crud will condense against the walls of the pipe if a) the walls of the pipe are too cool and/or b) the draft will be negatively affected due to cool or prematurely cooling gases from the fire]. There are two reasons people use double-walled or even insulated pipe. One is that it is much, much safer; the other is that the insulated nature of the passage keeps the "smoke" hotter until it emerges from the top of the chimney and that not only assists adequate drafting but also lessens the condensing of the crud inside the pipe.

You will find that you will have to clean your pipe quite frequently, if you use single-wall, regular stovepipe outdoors and that you will probably have to replace this pipe every two or three years due to its corroding out. I can almost guarantee that.

The insulated, double-walled pipe is quite expensive, but mine has been in operation for over 25 yr. I have had to replace no parts at all in that time and it is still in great condition today. Also, and I do burn seasoned wood, in all those years I have checked the pipe yearly but never had to clean it out. Never.

Previous to this house, I lived in an old miner's shack for ten years. It had a chimney made of the cheap, black steel pipe and I had to replace it every year. It wasn't much money, but it would rust and corrode out in one burning season. Also, I had to clean it out every three or four weeks, a mess and another big chore. It was a rental place, and I wasn't willing to pay for good pipe, which I would have had to do since the owner did nothing to the place. Part of my rent was fixing and repairing windows, shingles, etc.

 

[Pagey]

Bottom line: it's not safe. Single wall has a CTC (clearance to combustibles) of 18". It will also lose integrity over time, much faster than Class A chimney sections. It won't keep flue gases hot enough to prevent creosote buildup.

 

[begreen]

Three issues here: functionality, code and most importantly - safety.

The flue is going to want to be heading uphill as soon and as much as possible. Elbows add considerable resistance to draft. Too many of them and the flue won't draw. They are also creosote pockets. So try to eliminate as many as is practical. There is also fire code to consider. Your insurance company certainly will. Code is about safety, mostly about clearances, but also about keeping the flue warm enough so that creosote accumulation is minimized. Single wall pipe gets very hot. It needs to be at least 18" away from any combustible surface. Double-wall connector pipe has a clearance of 6". As soon as a wall or floor penetration is made, you need to go to class A pipe which is clearance rated at 2". Note, for the stove, 36" in each direction will be the clearance requirement unless it has been UL tested to closer clearances.

I suspect the OP question is about money. If so, ask yourself what the cost will be if there is a loss due to fire? What if the loss are expensive tools? What if that loss is human? Things to think about.

 

[jeff_t]

Some friends bought a house over the summer, and I got to check out the previous owner's similar garage install. Three feet up, 90 into a 24" section of class A thru a tight fitting hole in the OSB and vinyl siding, then horizontal for another six feet under a lean to on the back of the garage, then a 90 up. No verical pipe, just terminated in a 90. The horizontal run was supported by a strategically placed piece of plumber's tape.

Wish I had taken some pictures. Kinda sounds like what you want to do. Once you see it it's pretty scary.

 

[gapman789]

Guys, thanks for the great info.

Where to start....The garage would only be heated periodically throughout the winter. Maybe once a month, for a week at a time, or a couple of days a week.
My occupation is concrete construction so I'm going to have alot of down time this winter. Which gives me time to work on my roadracing motorcycles. End of the racing season maintenance basically.

Money is an issue but so is safety. Because of the limited time that I will actually be spending in the garage during the cold months, it's hard to justify spending $700+ for double wall pipe to make a chimney out of.

I won't be storing any gas, paints, thinners, etc...of that nature in the garage. I do have another small shed for that.
There are (4) motorcycles in the garage though.

The creosote issue is what I was missing as far as the heat/gases had to remain hot until escape from the stack to prevent creosote build-up. I couldn't find out why regular black stove pipe couldn't be used as a chimney. Now I understand.

I also understand the issue with too many elbows. Like I said, I would have an elbow coming out of the stove to turn the pipe upwards, then another elbow to get the pipe horizontal and thru the wall, where I would need a 3' double wall pipe going thru the wall, then another elbow outside the wall to complete the stack 2-3 ft. above the peak of the roof.

So, from what I gather from all this info is that I can use stove pipe for the chimney but it is not recommended.
I don't mind the extra maintenance involved in cleaning the pipe. With the minimal use that I would be using the stove, I'm not so sure I would have to clean it as often as some would think.
I understand that seasoned wood also cuts down on creosote deposits.

The roof is made of metal, corrugated? It has 'ribs' so to speak and is quite thick. I do no want to cut a hole in it, so that's why I was going through the wall.

Here's pics of the garage. The stove would be on the backside. No windows or doors on the backwall.
The stove will be just about where the red motorcycle is and 5'-6' from the backwall.

Am I missing anything? Again, thanks for the great info.

 

[SteveKG]

I understand why you would want to avoid cutting thru the roofing. However, there are specially designed boots for attaching to corrugated roofing for just this situation, and they work very well. You would only have the one elbow then, coming out the back of your stove and the rest a straight, simple shot up to the top. Put in some guy wires to secure the chimney, and you are in business. Very simple, no going thru the back wall and up past eaves, etc.

Might want to reconsider...this would not be a huge mental job for you as a contractor, you must have some construction smarts already.

 

[gapman789]

Some friends bought a house over the summer, and I got to check out the previous owner's similar garage install. Three feet up, 90 into a 24" section of class A thru a tight fitting hole in the OSB and vinyl siding, then horizontal for another six feet under a lean to on the back of the garage, then a 90 up. No verical pipe, just terminated in a 90. The horizontal run was supported by a strategically placed piece of plumber's tape.

Wish I had taken some pictures. Kinda sounds like what you want to do. Once you see it it's pretty scary.

LOL, yeah, sounds about right.
I'm in the construction biz, so I can build 'stuff'. I'm not trying to completely hack this thing in.

I keep thinking that there was a time when there was no double wall or Class A pipe.
And the early settlers managed just fine...

 

[humpin iron]

.......There was also a time when a piece of scrapwood was used as a bullfloat........How much to replace those bikes and all the other stuff.......ya know early racers wore jeans and tee shirts, not that expensive leather suit hangin on the wall....they managed.
Do it right or don't do it

 

[gapman789]

I understand why you would want to avoid cutting thru the roofing. However, there are specially designed boots for attaching to corrugated roofing for just this situation, and they work very well. You would only have the one elbow then, coming out the back of your stove and the rest a straight, simple shot up to the top. Put in some guy wires to secure the chimney, and you are in business. Very simple, no going thru the back wall and up past eaves, etc.

Might want to reconsider...this would not be a huge mental job for you as a contractor, you must have some construction smarts already.

Yea, I have reconsidered the option of going thru the roof. That was my original intention. There is no ceiling, only rafters, then OSB, then the corrugated roof.
In additon to simplifying the install, I would then only need a 3'-4' double wall coming out of the roof, correct? I could use stove pipe all the way up to the roof? Or is double wall again recommended to run all the way up from the stove thru the roof?

Half of the garage that you see in the pic, is insulated and has a plywood wall. The other half is not unsulated. ONly 2x4 studs with CELOTEX brown board on the outside, and then wrapped with wood lap siding.

 

[Later]

I once had a neighbor that used stove pipe as his chimney and finally realized that, after his third annual chimney fire, that it wasn't a good idea. The wrath of the local FD helped make him understand.

 

[certified106]

On a side note nice SV. Sold mine last year and man do I miss it!

 

[Backwoods Savage]

Welcome to the forum gapman789.


Some great advice has been given. I will only add that if and when you do this, the horizontal section must have some rise. 1/4" per foot of horizontal is the minimum. You might do much better with a couple of 45's rather than the 90's.

 

[rdust]

In additon to simplifying the install, I would then only need a 3'-4' double wall coming out of the roof, correct?

Class A chimney needs to be used to go through and above the roof.

 

[rijim]

Might want to check codes before installing stove in a garage. I think NFPA standards don't allow stoves in any garage; if your state adopted the NFPA Standard as a code then you may have a problem with inspectors and insurance company.

May be worth checking,
Jim

 

[CTYank]

Three issues here: functionality, code and most importantly - safety.

The flue is going to want to be heading uphill as soon and as much as possible. Elbows add considerable resistance to draft. Too many of them and the flue won't draw. They are also creosote pockets. So try to eliminate as many as is practical. There is also fire code to consider. Your insurance company certainly will. Code is about safety, mostly about clearances, but also about keeping the flue warm enough so that creosote accumulation is minimized. Single wall pipe gets very hot. It needs to be at least 18" away from any combustible surface. Double-wall connector pipe has a clearance of 6". As soon as a wall or floor penetration is made, you need to go to class A pipe which is clearance rated at 2". Note, for the stove, 36" in each direction will be the clearance requirement unless it has been UL tested to closer clearances.

I suspect the OP question is about money. If so, ask yourself what the cost will be if there is a loss due to fire? What if the loss are expensive tools? What if that loss is human? Things to think about.

What he said ^^^.

IME, single-wall outside a structure typically has so much pyroligneous acid (aka "creosote") condensing that it drools the stuff at joints, and the stuff literally eats away the steel of the pipe. IOW very bad idea.

 

[gapman789]

Three issues here: functionality, code and most importantly - safety.

The flue is going to want to be heading uphill as soon and as much as possible. Elbows add considerable resistance to draft. Too many of them and the flue won't draw. They are also creosote pockets. So try to eliminate as many as is practical. There is also fire code to consider. Your insurance company certainly will. Code is about safety, mostly about clearances, but also about keeping the flue warm enough so that creosote accumulation is minimized. Single wall pipe gets very hot. It needs to be at least 18" away from any combustible surface. Double-wall connector pipe has a clearance of 6". As soon as a wall or floor penetration is made, you need to go to class A pipe which is clearance rated at 2". Note, for the stove, 36" in each direction will be the clearance requirement unless it has been UL tested to closer clearances.

I suspect the OP question is about money. If so, ask yourself what the cost will be if there is a loss due to fire? What if the loss are expensive tools? What if that loss is human? Things to think about.

What he said ^^^.

IME, single-wall outside a structure typically has so much pyroligneous acid (aka "creosote") condensing that it drools the stuff at joints, and the stuff literally eats away the steel of the pipe. IOW very bad idea.

But if I ran the chimney straight up thru the roof, would it be ok to used single wall black pipe straight up from the stove toward the roof, and then have the double wall or Class A pipe going thru the roof and above?

 

[Pagey]

Single wall inside is fine, just try to keep the run to 10' or less for optimal performance. Then you make the transition to Class A double wall at the ceiling support.

 

[stevetford]

With toys like that in the garage, I would have the stove going 24/7. Just thought I would add that as everything else has been covered. Good luck with the install and next racing season.

 

[gapman789]

With toys like that in the garage, I would have the stove going 24/7. Just thought I would add that as everything else has been covered. Good luck with the install and next racing season.

Thanks for the good luck. Been racing off and on for 16 yrs. I can't get away from it....yet.
I've thought about keeping it heated all winter long as well.
I've looked into overhead propane heaters, etc...The problem is, only half the garage is insulated. It wouldn't take much for me to insulate and hang OSB on the walls. The roof is wide open though. No ceiling. Just rafters and the roof.
Wood is free. I got the stove for cheap. So I figure heating with wood, would be the most cost efficient. Besides, I enjoy cutting wood and being outside. The wood stove would just be another reason for me to get out of the house and away from the ole lady..lol. j/k babe.

I winterized the bikes today just in case my stove plans fall through for now. Getting in the low 20's the next couple nights. In racing, you're not allowed anti-freeze in the bikes. Only distilled water and 'WATER WETTER'. So, I had to get the water out of the bikes and put in 100% anti freeze.
FYI, anti freeze is more difficult to clean up on the track than oil that's why it is illegal to have in your racebike.

I'm not trying to keep the garage at 70 either. Hell, give me 50, maybe 60 degrees and I'm good.
I wouldn't mind keeping the stove going 24/7 thru the cold months, unless it became too much trouble.

I'm beginning to lean toward going through the roof. My employer/boss/friend has a galvanized double wall or triple pipe that sits on the roof. It has the cap and the base plate.
I'm not sure if I'm using the correct terminology. Base plate?

 

[DonNH]

I did the same thing as a quick way to get heat in my detached garage for 1 season. Finally had the garage doors installed in February and was looking to be able to heat it for the rest of the winter. Had a used pc of 10" class A to use as a thimble through the wall. Several sections of used metal roofing around the stove to protect the walls, etc. Kept the stovepipe a couple feet from the outside wall for the run up, and a couple feet higher than the ridge.

Had to work to get draft, and got lots of condensation in the pipe - when running continuous would get a steady drip of nasty black water on the ground under the pipe.

The following summer I kept my eye on Craigslist, and got a pretty good deal on some new class A pipe.
Ordered the miscellaneous extra pcs - spent about $800~900 total for 16' vertical run plus thru-wall pc, Tee & cap.

Definitely works better, no worries, no dripping.

Don

 

[firefighterjake]

Some friends bought a house over the summer, and I got to check out the previous owner's similar garage install. Three feet up, 90 into a 24" section of class A thru a tight fitting hole in the OSB and vinyl siding, then horizontal for another six feet under a lean to on the back of the garage, then a 90 up. No verical pipe, just terminated in a 90. The horizontal run was supported by a strategically placed piece of plumber's tape.

Wish I had taken some pictures. Kinda sounds like what you want to do. Once you see it it's pretty scary.

LOL, yeah, sounds about right.
I'm in the construction biz, so I can build 'stuff'. I'm not trying to completely hack this thing in.

I keep thinking that there was a time when there was no double wall or Class A pipe.
And the early settlers managed just fine...

HehHeh . . . there was also a time when the early settlers had wooden chimneys and many did just fine . . . but after a number of fires some folks caught on that maybe this wasn't such a great idea from a safety standpoint and made the change.

By the way, welcome to the forum Gapman . . . sounds as though you have every intention to do things right . . . do things as inexpensively as possible (which is fine) . . . but not at the expense of safety.

 

[SteveKG]

Some friends bought a house over the summer, and I got to check out the previous owner's similar garage install. Three feet up, 90 into a 24" section of class A thru a tight fitting hole in the OSB and vinyl siding, then horizontal for another six feet under a lean to on the back of the garage, then a 90 up. No verical pipe, just terminated in a 90. The horizontal run was supported by a strategically placed piece of plumber's tape.

Wish I had taken some pictures. Kinda sounds like what you want to do. Once you see it it's pretty scary.

LOL, yeah, sounds about right.
I'm in the construction biz, so I can build 'stuff'. I'm not trying to completely hack this thing in.

I keep thinking that there was a time when there was no double wall or Class A pipe.
And the early settlers managed just fine...

HehHeh . . . there was also a time when the early settlers had wooden chimneys and many did just fine . . . but after a number of fires some folks caught on that maybe this wasn't such a great idea from a safety standpoint and made the change.

By the way, welcome to the forum Gapman . . . sounds as though you have every intention to do things right . . . do things as inexpensively as possible (which is fine) . . . but not at the expense of safety.

Few yr. back, I had occasion to do some research in local newspapers around here going back into the mid-nineteenth century. While I perused these old pages, I realized that I kept coming upon stories of stove-caused fires. Of course, back then, in this area of cold winters, every single structure had a stove or more. If a cause was given, it was usually something to do with the stovepipe or chimney. Stovepipes running thru wood walls, wood roofs, etc.