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Thread: Flue pipe

  1. #1
    Join Date
    Apr 2014
    Location
    Connecticut
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    41

    Default Flue pipe

    I have an 18x48 evaporator that has a 7 inch pipe can I use an adapter to connect it to my existing 6 inch
    Pipe with out creating an issue
    Thanks

  2. #2
    Join Date
    Jan 2016
    Location
    MA
    Posts
    588

    Default

    What brand of evaporator is it? The Canadian brands that I’ve used (CDL and D&G) have pretty small fireboxes. My calculations suggest that going from 7” to 6” pipe would result in a loss of just over 25% of the capacity of the flue. Not sure how much that would affect its operation. You may not be able to get as hot a fire as you would otherwise but that may not end up mattering too much. You could try it for a season and then change it out if you were unhappy.
    60ish taps on buckets
    D&G Sportsman 18x63
    Turbo RB15 RO Bucket

  3. #3
    Join Date
    Apr 2019
    Location
    Nashville, MI
    Posts
    939

    Default

    That would be almost the same as a 24 x 36 small brothers barrel evaporator and those have a 6 inch pipe. I agree with ecobeck, you can try it and if it reduces you drafting ability in your firebox, then you will know.
    2004 - 2012 2x3 flat pan 25 to 60 taps
    2012 2x3 new divided pan w/draw off 55 taps
    2018 - didn't boil surgery - bought new evaporator
    2019 new SML 2x4 raised flue high output evap. 65 taps
    made 17 gal. syrup
    2020 - only put out 53 taps - made 16.25 ga.l syrup
    2021 - Didn't work out
    2022 - 25 taps on bags / 8 taps on 3/16's line - late start

  4. #4
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    May 2015
    Location
    Vermont
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    185

    Default

    I'd say if you have forced air you will most likely be fine. If you are depending on natural draft id stay away from reducing because it may equal many many more hours in the sugar house due to the fact your fire will not get as hot.

  5. #5
    Join Date
    Apr 2014
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    Wakefield,New Hampshire
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    Default

    If you are relying on natural draft and decide to reduce down to 6 inch before changing the whole system. You could try and extend your chimney pipe out the roof a few more feet to make up for some lost draft. When i added a few feet to my 8 inch stove pipe to clear the cupola it made a noticeable difference in the roar of the fire once i shut the door. I had a 3ft base stack and 10ft of chimney before adding another 3ft section at the top. Not sure if this is the right approach for your set up, but it's cheaper than changing over to all 7 inch.
    6th season solo sugar maker in a young sugar bush of mostly red maples
    320 taps
    2x6 self built arch, Flat pans w/ dividers
    New 12x16 sugar house
    CDL hobby 250 RO

  6. #6
    Join Date
    Jan 2011
    Location
    Southern Ohio
    Posts
    1,349

    Default

    NhShaun is on the right track I believe. Just reduce and go higher by one section of pipe.
    125-150 taps
    Smokey Lakes Full pint Hybrid pan
    Modified half pint arch
    Air over fire
    All 3/16 tubing
    Southern Ohio

  7. #7
    Join Date
    Feb 2013
    Location
    Volney, NY
    Posts
    275

    Default

    Quote Originally Posted by emq View Post
    I have an 18x48 evaporator that has a 7 inch pipe can I use an adapter to connect it to my existing 6 inch
    Pipe with out creating an issue
    Thanks
    If it has a 7 inch pipe, I wouldn’t change to 6”.

  8. #8
    Join Date
    May 2013
    Location
    Sugar Camp, Wisconsin
    Posts
    298

    Default

    When I moved inside my sugar shack I had to add 3 feet of 6" to my evaporator and now it pulls much more draft. I think like NhShaun suggests its a balance of flue diameter to length. For piping / fluids (combustion gas is a fluid) a reduction in pipe diameter will cause an increase in the flow speed jay
    Zucker Lager

  9. #9
    Join Date
    May 2009
    Location
    UVM Proctor Maple Research Center, Underhill Ctr, VT
    Posts
    6,391

    Default

    Quote Originally Posted by Zucker Lager View Post
    For piping / fluids (combustion gas is a fluid) a reduction in pipe diameter will cause an increase in the flow speed jay
    Physics are similar inside the tree as well. Sap flows faster around (but not through) non-conducting wood (stain) generated by tapping or other wounds than in areas without stain.
    Dr. Tim Perkins
    UVM Proctor Maple Research Ctr
    http://www.uvm.edu/~pmrc
    https://mapleresearch.org
    Timothy.Perkins@uvm.edu

  10. #10
    Join Date
    Jan 2011
    Location
    Southern Ohio
    Posts
    1,349

    Default

    I looked up a draft calculation and if I done it right you will need to increase your stack height by 3 feet if you go down to 6" pipe. This will maintain the same approx. draft.
    125-150 taps
    Smokey Lakes Full pint Hybrid pan
    Modified half pint arch
    Air over fire
    All 3/16 tubing
    Southern Ohio

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