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Thread: Distance between rafter and smoke stacks and steam stacks

  1. #1
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    Default Distance between rafter and smoke stacks and steam stacks

    Iím getting mixed distances from combustibles around the smoke stack of my evaporator? My roof joists are 24 inch centers I have a 10 inch smoke stack. And the distances between steam stacks and the joists if there is any?
    2011 55gallon drum evaporator 25 buckets;2012 shanty, and 2 1/2x8 evaporator, 200 buckets;2013 400 buckets; 2014 752 buckets 250gph RO, filter press;2015 1000 taps on line ; 2016 sold equipment, sold sap; 2017 sold sap; 2018 logged woods, added another sugar bush, 250 taps on high vac, 2x6 leader with max flu, new MES dolly 300, made 138 gal syrup; 2019 new CDL 600 expandable, new Wes filter press , bigger generator, 500 taps made 110 gal syrup; 2020 800 taps new vacuum pump.

  2. #2
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    The steam stacks can even touch the lumber. The smoke stack if single wall needs to be protected. Mine is single wall, initially I just made my own triple wall pipe. At that time my stack was 8" on a 2x6. I made an 11" that went over the stack and had 1.5" sheet metal homemade stand offs to hold it at 1.5" from the stack. Then I made another layer 14" diameter and repeated. I left the tops and bottom of my added stack open. That worked well. I had it start 2' below the bottom cord of the trusses and it was up to within 1" of the steel roofing and cut to have the top uniformly about 1" below the steel roofing.
    My trusses are 24" too, but for just the one where the stack is I moved that truss so one is 30" opening and the next one is 16" and then the rest are at 24" center to center.
    My current smoke stack I changed my method. For that I bought a roll of ceramic insulation 2" thick. Then I made an outer cover out of galvanized sheet metal to protect the insulation. At the bottom I cut about 1.75" slits in that cover and bent them inward. Each was 1" wide. That way the insulation could not slide out the bottom. I then suspended that cover from the rafters to hold it up. Either method worked well, the second just looks better.
    The formula for distance from the stack that is run as hot as an evaporator runs is to have 36" clearance. Then every layer of metal spaced at least 1" from the stack or the previous layer cuts the necessary clearance in half. Thus 1 gives 18" needed, 2 gives 9" needed and 3 would give 4.5" if you need to go that far. My old one was 2 layers and it gave me the necessary space. Either will be just as safe. The ceramic blanket was quite pricey. But 1.5" was enough to keep the outside from getting hot to the touch, it only gets to maybe 100 degrees, under 300 is safe. Over 300 slowly drives wood gases from the lumber and after long enough it will actually get to where 300 degrees will ignite it.
    Dave Klish about 1320 taps in '15, doing fewer each year, about 450 planned for 2020 (and after?)
    2012 Mahindra 36 HP 4x4/ loader/cab/heat/AC:-)
    added a gooseneck equipment trailer and F350 to tow it to haul more sap
    3x8 raised flue evaporator
    250 GPH converted to electric, RO by Ray Gingerich
    6.32 KW solar system, 1.48KW is battery backed up, all net metered
    http://s1041.photobucket.com/albums/...anssugarhouse/
    website: www.cnymaple.com

  3. #3
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    Quote Originally Posted by maple flats View Post
    The steam stacks can even touch the lumber. The smoke stack if single wall needs to be protected. Mine is single wall, initially I just made my own triple wall pipe. At that time my stack was 8" on a 2x6. I made an 11" that went over the stack and had 1.5" sheet metal homemade stand offs to hold it at 1.5" from the stack. Then I made another layer 14" diameter and repeated. I left the tops and bottom of my added stack open. That worked well. I had it start 2' below the bottom cord of the trusses and it was up to within 1" of the steel roofing and cut to have the top uniformly about 1" below the steel roofing.
    My trusses are 24" too, but for just the one where the stack is I moved that truss so one is 30" opening and the next one is 16" and then the rest are at 24" center to center.
    My current smoke stack I changed my method. For that I bought a roll of ceramic insulation 2" thick. Then I made an outer cover out of galvanized sheet metal to protect the insulation. At the bottom I cut about 1.75" slits in that cover and bent them inward. Each was 1" wide. That way the insulation could not slide out the bottom. I then suspended that cover from the rafters to hold it up. Either method worked well, the second just looks better.
    The formula for distance from the stack that is run as hot as an evaporator runs is to have 36" clearance. Then every layer of metal spaced at least 1" from the stack or the previous layer cuts the necessary clearance in half. Thus 1 gives 18" needed, 2 gives 9" needed and 3 would give 4.5" if you need to go that far. My old one was 2 layers and it gave me the necessary space. Either will be just as safe. The ceramic blanket was quite pricey. But 1.5" was enough to keep the outside from getting hot to the touch, it only gets to maybe 100 degrees, under 300 is safe. Over 300 slowly drives wood gases from the lumber and after long enough it will actually get to where 300 degrees will ignite it.
    I have extra 12 inch stainless stack I can slip over and take the ceramic blanket and stuff that in between the 10 inch and 12 inch. But your saying thatís not enough insulation?
    2011 55gallon drum evaporator 25 buckets;2012 shanty, and 2 1/2x8 evaporator, 200 buckets;2013 400 buckets; 2014 752 buckets 250gph RO, filter press;2015 1000 taps on line ; 2016 sold equipment, sold sap; 2017 sold sap; 2018 logged woods, added another sugar bush, 250 taps on high vac, 2x6 leader with max flu, new MES dolly 300, made 138 gal syrup; 2019 new CDL 600 expandable, new Wes filter press , bigger generator, 500 taps made 110 gal syrup; 2020 800 taps new vacuum pump.

  4. #4
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    I built my own triple wall also, but ran it right through the roof and into the flashing, which is perforated under the storm collar. I was curious to know how well this would work, so I put one of those magnetic chimney thermometers on the outermost stack. When my flue is running at 800 or 900 degrees, the outer layer never reaches 80 degrees...even when it's way too hot in the sugarhouse.

  5. #5
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    1" of ceramic insulation may be OK, but not if you stuff it in. You want to wrap it around the inner stack and then put the outer one on. That might be real hard to get. If you look at many class A chimneys they use 1" of ceramic insulation and that rates good for 2" clearance to the wood. If you stuff the insulation in you will compress the insulation, the non compressed air between the fibers is what insulates, if compressed the insulation factor drops significantly. The ceramic fibers are needed to hold up to the heat closer to the inner stack.
    Dave Klish about 1320 taps in '15, doing fewer each year, about 450 planned for 2020 (and after?)
    2012 Mahindra 36 HP 4x4/ loader/cab/heat/AC:-)
    added a gooseneck equipment trailer and F350 to tow it to haul more sap
    3x8 raised flue evaporator
    250 GPH converted to electric, RO by Ray Gingerich
    6.32 KW solar system, 1.48KW is battery backed up, all net metered
    http://s1041.photobucket.com/albums/...anssugarhouse/
    website: www.cnymaple.com

  6. #6
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    So I got the stacks in had to box truss on the smoke stack to give me clearance to insure that this resurrected old sugar shanty doesnít burn down. Itís about a mile of the road so the fire trucks wouldnít make it. I still have to make a double wall pipe at the roof but glad I got my stacks up! This is what I did.56C7CEC5-D01C-49C0-916B-5715FA242F61.jpg
    2011 55gallon drum evaporator 25 buckets;2012 shanty, and 2 1/2x8 evaporator, 200 buckets;2013 400 buckets; 2014 752 buckets 250gph RO, filter press;2015 1000 taps on line ; 2016 sold equipment, sold sap; 2017 sold sap; 2018 logged woods, added another sugar bush, 250 taps on high vac, 2x6 leader with max flu, new MES dolly 300, made 138 gal syrup; 2019 new CDL 600 expandable, new Wes filter press , bigger generator, 500 taps made 110 gal syrup; 2020 800 taps new vacuum pump.

  7. #7
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    I did the ceramic insulation outside of a 8" stove pipe then put a 10" steel duct pipe around it. It's not easy but about 1/4 the price of double wall pipe and the same result. Just make sure that you cut the insulation long enough.
    Matt,
    Minehart Gap Maple

  8. #8
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    Albion PA
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    Quote Originally Posted by calvertbrothers View Post
    So I got the stacks in had to box truss on the smoke stack to give me clearance to insure that this resurrected old sugar shanty doesnít burn down. Itís about a mile of the road so the fire trucks wouldnít make it. I still have to make a double wall pipe at the roof but glad I got my stacks up! This is what I did.Attachment 19078
    The rafter spacing (boxing) looks good. Do you have a roof jack? Doesn't look like it from the picture? You double wall needs to go through the roof or up into a roof jack to extend the distanse for any combustables. like the plywood or shingles. I almost burnt our sugarhouse down due to excessive stack temps getting this wood to catch on fire. I was lucky I had water available.
    Regards,
    Chris
    Casbohm Maple and Honey
    600 roadside taps
    3x10 King, WRU, AOF and AUF
    12" SIRO Filter Press.
    2015 Ford F250 PSD sap hauler
    One Golden named Maggie Cat named Lucy
    Too many Cub Cadets
    Ford Jubilee and several Allis WD's, and IH tractors

    www.mapleandhoney.com

  9. #9
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    Quote Originally Posted by Sugarmaker View Post
    The rafter spacing (boxing) looks good. Do you have a roof jack? Doesn't look like it from the picture? You double wall needs to go through the roof or up into a roof jack to extend the distanse for any combustables. like the plywood or shingles. I almost burnt our sugarhouse down due to excessive stack temps getting this wood to catch on fire. I was lucky I had water available.
    Regards,
    Chris
    Yes it does have roof jacks but I can get the double wall up into the jack about 3 inches above the roof
    2011 55gallon drum evaporator 25 buckets;2012 shanty, and 2 1/2x8 evaporator, 200 buckets;2013 400 buckets; 2014 752 buckets 250gph RO, filter press;2015 1000 taps on line ; 2016 sold equipment, sold sap; 2017 sold sap; 2018 logged woods, added another sugar bush, 250 taps on high vac, 2x6 leader with max flu, new MES dolly 300, made 138 gal syrup; 2019 new CDL 600 expandable, new Wes filter press , bigger generator, 500 taps made 110 gal syrup; 2020 800 taps new vacuum pump.

  10. #10
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    Albion PA
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    Sounds good! Anything to protect that sheeting and shingles from the direct heat from the stack is a positive thing. The other thing to help monitor this is to put in or on, a simple stack thermometer. bolt on type is about $25. This can show you how hot your stack is maybe 4 feet above the arch. Mine used to run way too hot which I could control a little by not firing as hard. Several changes have reduced my stack temps considerably. (AOF and new flue pans)
    Regards,
    Chris
    Casbohm Maple and Honey
    600 roadside taps
    3x10 King, WRU, AOF and AUF
    12" SIRO Filter Press.
    2015 Ford F250 PSD sap hauler
    One Golden named Maggie Cat named Lucy
    Too many Cub Cadets
    Ford Jubilee and several Allis WD's, and IH tractors

    www.mapleandhoney.com

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