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Thread: Remade evaporator.

  1. #1
    Join Date
    Nov 2014
    Location
    Middlebury In. U.S.
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    69

    Default Remade evaporator.

    I posted earlier about my changes. I can't get to a boil. If someone could look back at that post with the pictures [I couldn't get then rotated] and give me some ideas .I would be forever grateful. Thanks in advance .

  2. #2
    Join Date
    Jan 2016
    Location
    Shelburne MA
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    My ideas are:

    1. Fire isn’t hot enough. Your previous post mentioned stack temp of 500 degrees. See if you can crank it to 900. Make sure your wood is well dried, etc.
    2. Based on your drawing there may be too much space underneath rear pan. Reduce the space to 1.5-2.0 inches and see if that helps.

    I would not try to block off the stack opening with bricks. Attempts to block the flow of flue gasses with dampers etc, are misguided. You do, however, want to push those flue gasses up against the bottom of the pan as much as possible.
    Last edited by ecolbeck; 02-12-2020 at 06:28 AM.
    55ish taps on buckets
    D&G Sportsman 18x63
    RB15 RO Bucket
    Stihl 044 and 026

  3. #3
    Join Date
    Jan 2017
    Location
    Quaker Hill, CT
    Posts
    271

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    Lots of things going on there.

    What size stack do you have going out your roof? If its a 6" stack you are going to want to bring the air gap under the entire back pan to be around 1-1.5 inches. An 8" stack would be 1.5-2.5 " of air gap. Don't worry about the opening in your transition piece its the air gap under the pan that makes all the difference.
    Are you using clean dry seasoned wood? Is it split down to wrist size pieces? Are you building the fire big enough? You are looking for 600+F for stack temps. Is your blower fan big enough?
    What part of the pan/s isn't boiling? The whole thing or just the back pan?
    Are you doing anything to pre-heat your sap?
    2017 25 taps on buckets got me hooked 1 gallon of sweet
    2018 51 taps on 3/16 tubing/ DIY oil tank evaporator 8.5gallons finished
    2019 60 taps 7 gallons finished ended season short
    2020 New 2x4 divided pan ready to get away from the headache that is steam table pans

  4. #4
    Join Date
    Nov 2014
    Location
    Middlebury In. U.S.
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    6" stack through the roof. wood stored inside from last year. 2 1/2 " at front of back pan and 1" at back of back pan. Exhaust opening is 3" x 20". Is that too much opening going to the 6" pipe?

  5. #5
    Join Date
    Jan 2016
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    Shelburne MA
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    254

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    Its possible that a 1" gap under the pan is too narrow. The area of the opening should be approximately equivalent to the 6" stack area.

    I think that the exhaust opening size is irrelevant.

    See if you can get a rip-roaring, face melting fire going and see what happens.
    55ish taps on buckets
    D&G Sportsman 18x63
    RB15 RO Bucket
    Stihl 044 and 026

  6. #6
    Join Date
    Jan 2017
    Location
    Quaker Hill, CT
    Posts
    271

    Default

    The Gap under your pan sounds like it is correct for a 6" stack. You are looking for 28 square inches of air space or slightly larger when you multiply the wide of the arch by the height of the air gap.

    What does the smoke coming out of the stack look like when you try to get a really hot fire going? All the signs are pointing to a fire that is isn't big enough or hot enough. I would start looking into if you are feeding enough air into the fire and feeding the fire enough wood.
    2017 25 taps on buckets got me hooked 1 gallon of sweet
    2018 51 taps on 3/16 tubing/ DIY oil tank evaporator 8.5gallons finished
    2019 60 taps 7 gallons finished ended season short
    2020 New 2x4 divided pan ready to get away from the headache that is steam table pans

  7. #7
    Join Date
    Nov 2014
    Location
    Middlebury In. U.S.
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    69

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    Thanks for the input. I'll be working with it today, trying modifications. Next week looks like good sap weather.

  8. #8
    Join Date
    Nov 2014
    Location
    Middlebury In. U.S.
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    Today I changed the air gap under my back pan to a straight 1 1/2 " That gives me 30 in. going to a stack of 28". Next boil will be with sap ..Hoping that will be Mon. or tue. Thanks for the help.

  9. #9
    Join Date
    Apr 2016
    Location
    SW Ontario
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    229

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    I read this fairly quickly and may have missed it... Probably a silly question, but how deep is your sap in the pans?
    Too deep and it will take forever (if ever) to get to a raging boil...

    If you still have problems after your next try, maybe try taking the blower off and just let the natural draft work on it?? I really don't have any experience with the fan force draft, but I think it is possible to have too much... forcing the un-burnt gasses out of the firebox too quickly?? Just a thought?

    and one more question.... Are the sides of your firebox bricked? I presume so, but its not noted in your sketch. In your sketch the firebox seems quite large for the size of pans.. ... You want to make sure you are reflecting the heat back into the fire, with brick, to ensure full ignition of the gasses.
    Last edited by wmick; 02-13-2020 at 08:33 AM.

  10. #10
    Join Date
    Nov 2014
    Location
    Middlebury In. U.S.
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    I made and installed a float box, and it is at 1 5/8 " of sap in the pan . The arch is fully bricked and insulated. Yesterday I raised up the extension floor up to within 1 1/2 " of the bottom of the pan. Bought a moisture tester and checked some of my wood supply. It runs from 6% to 14%. Going to get some cutoffs from the cabinet shop to burn with it. Looks like midweek I should try it.

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