How far to keep smoke stack from wood

[Flatfoot95]

I put my smoke stack up today and roof jack. The stack is 10 inches in diameter and is roughly centered between rafters with 2 foot centers. The jack is also 10 inches and is screwed down over the steel on the roof. Should this be OK? Any concerns?

[markcasper]

you should be fine. My stack is about 2 inches away from a 3x10 perlin, have never had any trouble with it too hot other than drawing some of the pitch out of the pine. If your concerned, you could nail a few short pieces of sheet rock onto the "hot" side of those trusses.

[Fred Henderson]

Brian, That is exactly the way my old one was set up and that is why the rafter caught fire. If you can take a piece of 14 or 16 inch and center it around your 10" right up to your tin roof I think it would be better and safer.

[WESTVIRGINIAMAPLER]

Brian,

I stapled 1/4" ceramic blanket all over the top, facing side and bottom on both sides of my stack on my trusses. I went about 12" on each side of the stack, so the insulation is about 36" across each truss. I had the stack wrapped, but 802 stated it would cause it to fail prematurely.

[maple flats]

I have 2' centers and with my original 7" stack on my old 2x6 and my 12" on my current 3x8 I made a triplewall pipe. My 12" has a 16" (2=8" joined) with tin spacers screwed on the inside and outside to maintain space and is then a 20" surrounds that (2x10"). each layer spaced at least 1" away cuts the required distance in half. These could also be oversized and attached with spacers directly to the rafter or truss, for these spacers you could use 1" pcs of copper tubing or such. Basically a hot unprotected pipe should have 36" clearance from any combustable. Remember, you run an evap extremely hot, protect the wood from the heat. Wood exposed to extreme heat over time gets broken down to essentially charcoal on the surface and charcoal has a much lower flash point than the wood has.

[Russell Lampron]

I put pieces of scrap metal roofing over the rafters where the stack goes through. My roof jack is also 11" diameter for my 8" stack.

Russ

[tapper]

The right amount of heat too close to wood will change the chemical composition of the wood to the point of spontaneous combustion. Attaching insulating material or fireproof materials directly to wood members does not work either because of heat transfer. The best way to protect yourself is try to have 18" from your stack to the nearest wood. If still in doubt suspend a metal sheild between the stack and the wood and mantain airflow between outside of sheild and the wood.

[Breezy Lane Sugarworks]

air space will be you BEST insulator!

[mountainvan]

tappers right. I've been there done that, ie had a nice little fire in(the wall) of the saphouse. That's when I had a half pint 15 years ago. Talk about smokey flavored syrup!! I have a foot between any wood and the pipe going through the roof.

[Fred Henderson]

After I caught my rafter on fire I kept a pressure garden sprayer near by all the times. When that season was over I took out one more rafter and covered the whole opening with metal. Then I redid the stack opening.

[maple flats]

I forgot one thing in my previous post. I designed the trusses for 2' on center spacing but where the stack was going up thru I moved one truss to 30" on center. This gave me about 28" between these trusses to run my stack exactly in the center. Another way would be to add some ceramic blanket in the space between the hot pipe and the combustables.

[Maplewalnut]

Does anyone use double wall insulated pipe? I run black stove pipe from my base stack a few feet up and then inserted a converter to insulated pipe through the roof and outside. Its a little pricey to purchase but cheap insurance against fire. The clearances to combustible surfaces then drops to 4 inches.

[mountainvan]

When I had a 2x6 I did, but still had 8" ll around. My dg came with a roof jack that is designed so it's double wall through the roof.

[tapper]

Double wall insulated pipe improperly installed at a freinds house set his house on fire. Be careful with that stuff!

[brookledge]

One thing that will affect things differently is, whether you have a steam hood or not. With a hood collecting the steam and taking it up and out will mean the wood rafters can get hotter and ignite easier. When the steam is going up and constantly surrounding the roof with steam it is less likely to catch fire. On my last evaporator I had about 8 to 10" of clearence and the rafters got a little charred over the years but never caught on fire.
Keith

[maple flats]

Around here we are required to get an inspection by the fire dept for any wood burning stove (evap included) and must meet their specs or we can not use it. My home made triple wall passed easily.
Dave

[maplehound]

you would think that the manufacturers would give us something to adress this problem. My father and i worked hard to come up with a system that we thought would work for use. We ended up cutting alot of our roof away and replacing it with ss metal over a fairly large area. just to make us both feel safe. I sure don't recomend it though in all aplications.

[Fred Henderson]

you would think that the manufacturers would give us something to address this problem. My father and i worked hard to come up with a system that we thought would work for use. We ended up cutting a lot of our roof away and replacing it with ss metal over a fairly large area. just to make us both feel safe. I sure don't recommend it though in all applications.

Most of the ideas that manufactures come up with have come from guys like us. Just remember we are the brains and researchers behind all successful manufactures.

[maplehound]

Fred,
While it is true that we are the one that give them the ideas, itis also tre that there ae other simular industries ( such as wood burning fireplaces) that have simular problems that have been addressed. They should be able to supply the buyer of these evaporatores with a proper system to safely go through our roofs. When I bought mine I was shocked to find out how little is offered in advice on how to do this.

[Fred Henderson]

Any wood burning appliance has to 18" from any combustable material. If you are going to run a wood fired evap and your don't know anything about go to the libaray and get some books. Read and learn. Same goes for anything that we want to learn how to do. Learn from someone else or read, read,read.

[brookledge]

I must say that I got good help and instructions when I bought my new evaporator in 2002. The dealer I bought it through delivered it and answered the questions I had and came back again to discuss another question. I may have paid more than some other brands but I'm happy with my evaporator.
My current 3X12 is my fourth new evaporator over 30 plus years and it came with very good instructions on how to set it up.
I think every manufactuer should not assume that the buyer knows how to set it up and it should come with instructions at the very least. Over the years I've been on the trader, I here over and over other members complaining about getting no instructions. We as a buyers should request better help in setting things up or tell them we will buy it elsewhere.
Just my 2 cents worth.
I know that in reguards to clearence around rafters will very alot depending on different building codes but the manufactuer should offer a guide line and know each states or regions building codes.
Keith

[maplehound]

I think they should be supplying a triple or double wall pipe for the section that goes through the roof. I havenever even seen one in any of there catalogs, and you sure can't find any around in the sizes that we need for these evaporaotrs. My stack is 14" in diameter and I don't think they even make a double or triple wall pipe that size. So why can't the manufactures come up with something for use?

[royalmaple]

What I did on my roof jack is something that you may want to consider. I had my roof jack made at a buddy's fabrication shop. So I had say in what was happening. Rather than a traditional roof jack that stops at the flashing collar. I had the pipe extend down another 2 1/2 feet through the roof into the sugar house. SO my stack goes through the whole thing and I have like 2 1/2 feet before the roof of double pipe from the inside, and then once through the roof I have like 14 or 16 inches sticking up through the roof.

Should work just fine and like I said I was having it made so really didn't add too much extra to have them do it that way. Also I had them make the jack pipe 14 inches and my stack is 12 inches, so I can put 1inch pieces of pipe as spacers to keep an air gap between the stack and the roof jack pipe.

Also you can cut out and head off one rafter where you are going through the roof if you have the space and then you are doubling the space between rafters. That is also what I did I ran the rafters 16 o.c. and then headed one off so I have roughly 29 inches inside the rafter to rafter.

[Flatfoot95]

Just wanted to say thanks to all for your input. I have just been so busy lately I havent had the chance to say thanks. I am going to try suspending some flashing on each side of the stack to deflect heat and possibly attach some ceramic blanket on the rafter behind the deflector. We'll see what happens cross your fingers.

[SteveD]

Brian,

I stapled 1/4" ceramic blanket all over the top, facing side and bottom on both sides of my stack on my trusses. I went about 12" on each side of the stack, so the insulation is about 36" across each truss. I had the stack wrapped, but 802 stated it would cause it to fail prematurely.


What is wrong with wrapping the stack....I can't find 802's comments on problems associated with doing that...
-Steve

[WESTVIRGINIAMAPLER]

He states it will lead to premature failure of stack due to no air being able to get to it and it makes sense.

As far as facing the trusses with ceramic blanket, I don't think they would ever be at risk for fire. If my stack were closer to them, I would have used 1" blanket as it reflects heat and doesn't trap it.

[SteveD]

That seems odd though....I don't see how a wrapped stack is much different from a stainless steel double walled insulated stove pipe...it only lacks the second layer of stainless.
-Steve

[HanginAround]

If you wrap the stack, the temps of the steel will be way higher. Not sure how they handle this in insulated chimenys, I guess other than the flue gases aren't as hot as in the stack of an evaporator.

[Pete33Vt]

It makes sense cause in a heating setup, where most of your insulated pipe is used you send all your heat into the house and not send it up the chimney.I have heard of insulated pipe burning out after a few years. On my rig I have plenty of room between the stack and any wood. Althought I have one cross brace that has a piece of fibre board spaced with electric fencing insulator to protect it from heat. The sugarhouse I used to boil at didn't have an protection where the stack goes through the roof. NO fun cutting out parts of the rafters with a rig boiling, steam in the sugarhouse and alot of chared burning wood.