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Thread: preheated AOF manifold build

  1. #1
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    509

    Default preheated AOF manifold build

    Hey all,

    As I was looking through some pictures today I found a good shot of my preheated AOF manifold outside the arch. I'm sure there will be plenty of AOF modifications to evaporators that don't have them in the off season so here is what I did. I hope this helps and would be willing to answer any questions.

    Due to the complexity of the manifold and my entry level welding skills I built it outside of the arch and then slid it in the back of the arch and once it was positioned in place I tacked it to the arch in several locations. It consists of a back air inlet 3" wide then to a back piece of tube steel (2"x6"?) then into 4x 1.5" pipes that go under the raised flue pan and transfer the firebox heat to the air passing through and end up in a front piece of tube steel. Off the front tube steel comes 2x 1.5" tube steel arms that have 3/8" pipe as nozzles to distribute the air into the firebox. The front piece of tube steel also have 4 nozzles that put air into the back of the firebox. The pictures below I have sketched some lines that depict the air movement.

    Preheated AOF manifold airflow.jpg

    In the second picture I have sketched on the arch where the pans sit in relation to the manifold. Half of the flue pan is exposed to the firebox.

    Arch AOF pan drawing.jpg

    The front and back tube steel in the manifold are oddly sized but that was what I had lying around. As far as the effectiveness of this setup, I don't have much to compare against since last year we were boiling on an oil tank arch with steam table pans on natural draft. It was efficiently burning wood as I had no visible smoke out of the stack even right after a reload. And I burned less than a cord for my 34.5 gallons syrup.
    2019 - 150 taps 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 taps 3/16 hybrid (shurflo), 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons
    2017 - 60 taps 3/16 gravity, oil tank arck w/ steam pans - 12.5 gallons

  2. #2
    Join Date
    Mar 2017
    Location
    Saratoga, NY
    Posts
    35

    Default

    Thanks for posting! I am new to AOF, but thinking it may be a good fit for my evaporator. Do you use a blower to force air through this or does it naturally draw? Were you having issue before doing this with incomplete combustion?

    Thanks

    Peter

  3. #3
    Join Date
    Jan 2011
    Location
    Poultney VT
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    2,442

    Default

    FYI leave air on in AOF until inside fire box temperature drops back down to 30C or so, this will prolong the life of the steel exposed to the high temperature and flame.
    Business Name
    Flat Lander Sugaring (who would think a guy from Az be making syrup)
    125 on Sap Suckers
    Close to 475 High Vac
    400 gravity adding more
    leader 2x6
    home made preheater
    hoods
    1 7D749 for AOF
    New FLS Tsunami Arch
    4 membrane TR Industries RO 2HP 3 phase 601GPH 250 PSI
    PID Display for Arch Temp.
    Chumlee of the trader

  4. #4
    Join Date
    Jan 2006
    Location
    Oneida NY
    Posts
    9,707

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    Quote Originally Posted by crzypete View Post
    Thanks for posting! I am new to AOF, but thinking it may be a good fit for my evaporator. Do you use a blower to force air through this or does it naturally draw? Were you having issue before doing this with incomplete combustion?

    Thanks

    Peter
    AOF needs a high pressure lower, not even a squirrel cage blower will do it. There is lots of information on this forum about AOF, check it out.
    One thing that will show you that you have incomplete combustion is to look at the top of the stack in the dark. That ball of fire is not flame that traveled the length of the arch and the stack, it is hot gasses that ran out of oxygen and re-ignited when it got oxygen. That is wood consumed that never added to the boil.
    Last edited by maple flats; 05-07-2018 at 06:57 AM.
    Dave Klish about 1320 taps in '15, down to about 700 in '16, up to 1000 for 2019?
    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

  5. #5
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    509

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    Quote Originally Posted by Flat Lander Sugaring View Post
    FYI leave air on in AOF until inside fire box temperature drops back down to 30C or so, this will prolong the life of the steel exposed to the high temperature and flame.
    Ya good tip. I usually let the air run to cool the arch faster after I stop adding wood.
    2019 - 150 taps 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 taps 3/16 hybrid (shurflo), 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons
    2017 - 60 taps 3/16 gravity, oil tank arck w/ steam pans - 12.5 gallons

  6. #6
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    509

    Default

    Quote Originally Posted by crzypete View Post
    Thanks for posting! I am new to AOF, but thinking it may be a good fit for my evaporator. Do you use a blower to force air through this or does it naturally draw? Were you having issue before doing this with incomplete combustion?

    Thanks

    Peter
    I used a bouncy house blower with good success. They work well and you can usually get one for under $100. This evap was built with AOF from the start but I can tell you that an evap with AOF will always have the most complete combustion in comparison to one without.
    2019 - 150 taps 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 taps 3/16 hybrid (shurflo), 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons
    2017 - 60 taps 3/16 gravity, oil tank arck w/ steam pans - 12.5 gallons

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