smoke stack

[wanabe]

Hi Guys,


Looking for some expert advice. The 2x8 I picked up is homebuilt, very professional looking but I think it may have a few minor problems. The first section of stack its store bought and tapers down to 8 inches Then goes into a reducer to 6 inch stack and has a damper in it. Is this big enough for a 2x8 and why is there a damper? I ran a 7 inch stack on my homebuilt 2x4 this year and had about 1 foot of the base stack cherry red a few times with the forced air running. I cant imagine 6 inch being enough but I dont know..


Thanks Jeff

[WESTVIRGINIAMAPLER]

Jeff,

I have a 2x8 drop flue Leader and mine has a 10" stack on it. I wouldn't mind even having 12", but I am going to a forced air and airtight front next year, so 10" is enough.

I don't think you want any less than 10". I have a stainless 11" base stack that is brand new and it is designed to fit any Leader style arch. All you would need is 4 more sections of 11" stainless or galvanized stack and now is the time to order it because you can get a 10% discount.

[WF MASON]

What do you have for a basestack 'Collar' for the basestack to sit on.?
Or is there no basestack ? just round pipe going up? If there is no basestack and collar , then thats where you'd want to start. Ten or eleven inch dia. is what you'd want.

[Seibold's Sugarhouse]

Is there a good rule of thumb about How far your smokestack should extend above your roof? I have a new 2x6 arch with the standard 12' of stack. The new leader arches are 33" off the floor and my floor to ceiling height in the new sugarhouse is 12' 8" or 152". Therefore I am left with about 2' of stack above the peak of the roof and only about 6-12" above the cupola roof. I plan to raise the arch 6-8" but I still don't know if that will give me enough clearance. I would hate to order another 3' of SS stack but I don't want to burn down my new sugarhouse either :!: :!: :!:
Also how far should the stack be from the roof rafters?? The Rafters are 16" o.c. and the stack is 10". That leaves me with about 1 - 1 1/2" of air space around the stack. Is this enough or should I face the rafters with something fireproof :?:
Thanks for the help,
Jason

[Al]

On the rafters I used some left over metal roofing and attached it on the rafters to hold off the heat. I predrilled the metal an put 6 flat washers for spacers on the back of the metal for a little airspace between the wood and metal. Then screwed them in.
Hope this helps.

[themapleking]

I would have your stack a least 8 ft above the roof peak. This will help blow those hot ashes some were away from the shack. At 2 ft you have a high risk of ashes falling on the roof.
I have about 4" - 6" of rafter space from the stack. NOT ENOUGH ROOM. THE RAFTERS STARTED TO BURN. Even with metal flashing. This year I rapped the stack with instullation blanket. The stack is about 3 ft from the wall and the wall even got too hot to touch.
My 2 cents.

[gmcooper]

If you only have 1 1/2 inches clearence between rafters and stack you really should cut of one and put in a header. Then move the evaporator forward or back enough to give at least 6" (more the better) If you use a metal heat sheild like scrap metal roofing it should be spaced 1" from wood and should be "L" shaped to provide sheilding on the bottom as well as side as your heat rises from stack and spreads out the higher it travels.
I scorched a rafter or 2 over the years and have seen many others do the same. Good luck!

[brookledge]

The rule of thumb as stated is 2X the length of your arch. That is usually considered the minimun. I would get it a few feet over the highest point of your roof. Basicly like most chimneys around are about 4' above the roof. I think one more 3' section will be good. You can always try it before to see if you have a good draft and if not add 3'.
Keith

[WESTVIRGINIAMAPLER]

Jason,

I know a little here and there soon adds up, but like they say, an ounce of prevention is worth a pound of cure. You need to do 2 things that won't take to long or cost very much. Invest in 1 more 3' section of stack and you will be plenty high enough. Next, get a roll of 1" ceramic blanket off of ebay for around $ 50. Then, wrap your stack with the ceramic blanket anywhere at all it is close to the rafters and strap it to the stack with wire. You may have to wrap 6 or 8 feet, but it won't take long as the blanket is 2' and it would take a 31.14" piece to wrap the stack(diameter x 3.14).

This will cost you around $ 120, but will be worth it a ton in the long run. With your current setup, this is about your only safe option. Make sure when you wrap the stack you don't leave any exposed stack until you get at least a foot below the rafters. Also, try to insulate good around the roof jack and roofing as this area could get hot too. :D

[pegjam]

I was ok with 12" clearance around my stack, (all four sides), until I put on a steamhood, then I scrouched rafters like crazy. Ended up doubling that distance. I would go nothing less than 18" now, and wrap the stack. It's easier to do that than build a new shack. Also get your stack at least 3' to 4' feet above nearest obsticale. If you have ever seen your stack catch fire, you'll know why. It looks like a rocket headed the wrong way. Looks cool, but can burn something down pretty quick. :lol: :lol: :lol:

pegjam
"Hope this helps, can't hurt"

[syrupmaker]

Pegjam, I have been a firefighter for quit a while and have never heard a chimney fire descibed that way. THATS AN AWSOME ANALOGY
Have heard it described as a rocket with an attitude though.

Rick

[Russ]

Before we added forced air, I recall a year where we had chimney fires almost daily. We cooked only in the daytime, so we never could see the flame coming out the top, but the entire stack was rattling enough to wake the dead. The stack thermometer was pegged all the way to the right. After 5 minutes or so, everything would settle down. After the first one or two times, we kind of learned to expect it. I don't recall it happening after we added the fan to the firebox; we must be burning cleaner and not getting any unburned fuel accumulation inside the chimney. It was awesome.

[saphead]

The first sugar house I worked at was owned by a tinknocker, his method of keeping things around the stack cool was to put the stack in a stack. He incorperated this into the roof jack and left a couple of inches clearance between the two. The storm collar was clamped onto the smoke stack a few inches above the top of the roof jack to allow room for air (and steam) to flow up and out. Depending on the clearance to combustables, the roof jack stack could extend down into the sugarhouse as far as was needed. I've also seen stacks go up through the cupola,hot air rises so it might as well all go up and out the same place!

[pegjam]

:lol: :wink: :lol:



pegjam
"Hope it helps, can't hurt"

[Iver]

You can get double walled pipe. It costs a bit more. A friend just got some for his woodstove installation. Maybe you could run that through a roofjack. Sheet metal fabricators made ours, you could have them make one that fits the double walled pipe.

[gmcooper]

I have to question how you get creosote build up on an evaporator stack. Generally I would belive the stack temp would be way to high for any build up? It might be possible but I have never seen any.
Last year in talking with both Leader and Bascoms that rocket burning at the top of the chimney is the flue gasses burning when they reach oxygen at the top of the stack. It does really roar and looks impressive (especially to the fire Dept.) But it comes from a lack of oxygen in the firebox to burn the gasses. Their statement was that if you see the flame you need more air. If you don't burn the gasses in the evaporator your losing btus that you have already paid for or at least worked for. Certain types of wood will poroduce more gasses than others.
Mark

[pegjam]

Coop:

I don't doubt what the "experts" say, but I have seen this happen a few times. First time I was boiling with green wood, which caused the buildup of cresolte, even with lots of draft. But the second time I was using dry wood, that was seasoned, with Lots of draft. That time I don't believe the gas was what was burning, I think the fire was just way too hot. :lol: :lol: :lol:
"Experts: Little dots under pressure."

peggjam
"Hope it helps, can't hurt"

[WESTVIRGINIAMAPLER]

I only burned dry seasoned wood that has been seasoned normally for 5 to 10 years, but usually at least two years. If your wood is seasoned correctly, you shouldn't have any problem with cresode buildup inside the flues. Seasoned wood will also provide more btus and better combustion! :D It also needs to be dry.

[ebourassa]

Alright i have a problem, I didnt design my shack right, my stack is about 6- 8 inches away from the wall, I have some ceramic blanket i can wrap the stack with, I want to know the pro and cons of that, and if anybody has any idea on what else i could do.

[WESTVIRGINIAMAPLER]

I think if you fully wrap the stack with 1" ceramic blanket where no stack is exposed and make sure the roof jack opening and roof boards are insulated good, you shouldn't have any problem. :)

Another material that helps keep heat off of the wall behind a woodburner is ceramic tile backer board. I have used the durock type in my vacation cabin for extra safety at about 12 inch wall clearance. You can stand it off on furring strips to give some more air circulation behind it.

Hope this helps. :)

[WESTVIRGINIAMAPLER]

You could also buy the sheets of insulating board that the evaporator companies sell. A 1' x 3' sheet is around $ 8.00.

[steve J]

After reading everything here about the height of the smoke stack I realize I need to add one more section to my stack as I am just above the roof line. My question is this the last section is insulated chimney pipe which is very pricey. this has an inside diameter of 6 inches is it possible to attach a galvinzed pipe to this or do I need another 4ft of the expensive pipe?

[WESTVIRGINIAMAPLER]

If the stack is on the outside, I don't think it would matter what you added to it. :?

[brookledge]

You shouldn't need insulated pipe. I'm assuming the only reason you did use it was to get through the roof to deflect the heat. If you have stainless the rest of the way then I would say to get a 3' piece to put on top to keep it from rusting. You could also make a stack cover to keep the elements out of you arch.