Stack Clearance

[steamvalleyFarms]

How close can my smoke stack safely be to a wall or rafters. I have a 3 x 12 evaporator that I am going to be setting up. Believe the stack is about 16" diameter.

Thanks,
Rob

[Dave Y]

Rob,
Give yourself a minium of 2ft clearance. I know that rig and the stack can get hot!

[mapleack]

If you have to have a rafter, say 6 inches away, or make major modifications, do this: get some 1/4 or 1/2 in thick cement board and cut a piece slightly larger than the area of the rafter, then cut 1/2 in long pieces of copper or steel pipe, and use them as spacers behind the cement board, that the screws pass through, to create an air gap. This will work fine, I did it on two rafters near my stack, never had a problem.

[steamvalleyFarms]

Thanks Dave,
another question I forgot to ask when I talked to you last night.
Thanks for all the other tips and suggestions also.

Rob

[PerryW]

My 15" 3x10 evap. stack is about 18" from the back wall. After a year or two, I noticed (while boiling) that it was smoldering and was turning the pine sheathing to charcoal!

I just took a piece of galvanized roofing and nailed it up with some spacers against the wood and it's been fine ever since.

[red maples]

mapleack's advice is good. they sell that heat reflector backer board the put behind woodstoves and stuff that works good. my sugarhouse is a little tight and that stuff works great.

another thing I read somewhere is to wrap 1" ceramic blanket ins. around it to act as insulated pipe!!

[Sugarmaker]

Thanks for the reminder. I need to do this to a rafter that is about 8 inches from my stack. It has been getting progressively darker the last couple years and I know it gets hot.
So maybe a project for tomorrow afternoon. Bend a piece of stainless to cover the rafter and space it out from the rafter and or cover with some insulation then the stainless.

My evaporator is about 3 feet from the back wall which is hemlock board and batton, it gets very warm also but no discoloration.

Regards,
Chris

[WESTVIRGINIAMAPLER]

My rafters are on 2' centers, so that means I have about 22 inches inside the rafters and I have 10" stack going between them. I have them completely covered within about 4' on each side of the stack with 1" ceramic blanket, so I don't ever forsee a problem. Amazes me that some are boiling without any protection and seeing it getting black or turning to charcoal. A roll of the 1" ceramic blanket is not that expensive and has many uses for years to come.

[Sugarmaker]

Yep, were an amazing bunch:)
I did bend some stainless and produced a 4 foot long shield for the rafter closest to the smoke stack. I provided a air gap between the stainless and the rafter. Should be much better/ safer for years to come.

Regards,
Chris

[maple flats]

Yes do protect it. Once wood has been made into charcoal it will ignite at a rather low temperature. If I remember correctly charcoal ignites at 300 something degrees, and close to the stack during a boil on a single wall uninsulated stack you will exceed that easily.

[skye]

I see a post saying a minimum of 2' clearance on either side of a 16" stack. I would like to provide 2' clearance in our new sugarhouse but that begins to push our cupola to far towards the front of the arch. We will be running a 4x12 with an 18" stack. Cupola is 8' long and we are using 2.5 x 10 rafters that are 2' on center. Thoughts anyone? Are we safe at 15" if we include a heat shield?

Thanks!

[Haynes Forest Products]

I think so mine is less. Another thing you can do is get the premade stove pipe from Home Depot. If your pipe is 12" then get a 10" piece and snap it over the 12" with a insulation in between. Put the seam towards the evap it will be a poor mans double wall and works great.

[WESTVIRGINIAMAPLER]

I have a 10" stack between trusses on 2' center which gives me about 6" on each side and I have the trusses covered with 1" of ceramic blanket about to about 2' past each side of the stack.

[mapleack]

My 12" stack passes within 4 inches of a rafter, about 8 feet up from the arch. I cut a piece of cement board and screwed it to the rafter, with half inch long pieces of pipe between the cement board and the rafter as spacers. The air space keeps it cool with no problems.

[Dennis H.]

Now do you all have metal roofing or is there plywood and shingles?

I stumbled upon this posting and have found the info handy.
I have an 8" stack that I have to run up thru a roof with rafters 16"oc and plywood and shingles.
My 2 options that I thought up are, 1, cut out the 2 rafters the are on each side of the stack then run a 2x6 perpendicure to the rafters so I sort of box in the area where the stack goes thru the roof or option 2, put ceramic blanket over all wooden parts that are next to the stack. I guess I would have to put some blanket on the edge of the subroof plywood either way.

[lastwoodsman]

I am at the same spot. ready to put a hole through my new steel roof which has 1/2 inch plywood under it. I am planning on flashing everything around the pipe. Cutting back plywood two foot square (rafters 2 foot on center. Should be enough space with flashing. Still am struggling with the best way to seal the pipe through the hole. Roof jack or other?
I keep reading and looking at the photos here.
woodsman

[Dennis H.]

Here is a question for you all, what ill effects if any will wrapping the SS stack with ceramic blanket have on the life of the SS stack?

I know now that I have to cut back and reframe 2 rafters and ceiling joists to get a confortable clearance with the stack and I will have to make a bigger hole under the roof jack.

My choices are to then wrap the SS stack with blanket where it goes thru the roof or attach the blanket to the roof it self.

Any ideas?

thanks

[WESTVIRGINIAMAPLER]

According to Jerry(802maple) and others on here, wrapping the stack with ceramic blanket will cause it to fail prematurely, so attach the blanket to the roof.

[802maple]

Brandon is correct, If cool air can't get to the stell it will fail, If you need to put up insulation I would put it on the material you are trying to protect and as mentioned on here before you could put a sheet of steel with air gap between the rafter. If you did both of the above you would be able to go to sleep at night knowing that it didn't get to hot.

[Dennis H.]

So what you are saying is cover the wood parts with ceramic blanket and then cover the blanket with a sheet of metal.

Would it be ok to have the metal right against the blanket but not compressing it or should you leave a small air gap between the metal and blanket?

Thanks guys for the info, I was thinking that I could save a little by just buying enough blanket to go around the stack. I'm glad you told me not to, I would have spent more in new stack later on down the road.

[skye]

Thanks for all the info everyone. We will cut out one rafter make a 4' box around the 18" stack then use a combo metal shield with spacers and ceramic blanket. And keep an eye for any charring.

BTW: Anyone out there have a sugarhouse fire? Please share your stories so we all can learn from the "what-not-to-dos" too. I am sure there are a few good ones.

Thanks-
Bobo

[802maple]

If you do all that you won't have any charring. I would leave an air gap if I were using the metal.

I know ceramic is expensive, but a little of that doesn't cost nearly as much as your sugarhouse and all of your equipment. Sometimes overkill isn't needed but in this case what the heck.

[Dennis H.]

Yeah the blanket isn't that expensive. I just picked up 24sqft of 1" blanket cost me $2.74/sqft. If I would have bought the entire roll I could have gotten it for only $2.03/sqft.

I got it at a pottery supply house. I actually called a local guy how makes pottery and just asked him where he gets his kiln supplies. Found out that it was only about 5 miles from my work so ran there this morning after work and got it.

I tried to get a roll off of ebay. found someone who was listing it for $67 per roll, 50sqft, but the shipping was $57!!!! Ouch! He even had a make an offer but when I tried that he would only come down $3.50. Wow what a deal!!:mad:

[802maple]

Try www.ceramicfiberonline.com

Remember there are temperature ratings of 2600 and 2300 plus 3 density ratings of 4,6 and 8 lb.

Alot of people think ceramic blanket is all the same and if someone pays $85.00 dollars a roll and another guy pays 60 that he got a better deal but they may have not be comparing apples and apples.

Obviously the higher temperature rating is more expensive but the higher the density rating is also higher.

2300 degree is ment to be used behind a layer of 2600 degree in high heat areas (such as your arch) but in this area of protecting your rafters you could get away with 2300 - 4lb insulation

[WESTVIRGINIAMAPLER]

If you wrap all the exposed wood within 2 or 3 feet of the stack with 1" ceramic blanket, you won't have to worry about anything catching on fire and wouldn't think you would need any metal in my opinion.

[802maple]

I have to agree with you Brandon, because the wood will not get to the flashpoint with just that. I was just saying that they could use it if they want alittle more assurance.