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Thread: New Forced Air Evaporator

  1. #1
    Join Date
    Jan 2012
    Location
    South Dayton NY
    Posts
    18

    Default New Forced Air Evaporator

    I would like to build a new forced air Evaporator with AUF and AOF. Would anyone be willing to share their experiences and maybe answer these questions-

    1. How large should the firebox be? - 2'x6' Arch

    2. What have people used for blowers?

    3. Anyone have a good door design including latch and hinges? Pictures or drawings would be great.


    Thank You
    2011 12 taps cooked on stove

    2012 150 buckets
    2x6 small brothers raised flue lightning
    Converted corner of old garage for sugar house

  2. #2
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    634

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    Here is my 2x6 build with AOF/AUF: http://mapletrader.com/community/sho...ch-build/page2

    To answer your questions
    1. For AOF and AUF build I believe 2/3 the length of the arch. My firebox is 4ft long and as wide as the arch minus insulation and fire brick

    2. Any high pressure blower will work. A cheap way to go is a bouncy house blower. I have had 2 seasons on mine and it has worked great.

    3. Doors can be as simple or complex as you want. There are good pics of mine in the build thread.

    Let me know if you have more questions on the build and I will answer as best as I can. One of the best places to start is knowing exactly how large your pans are so you can make all your rails to fit the pans exactly.
    Camp Wokanda
    Peoria Park District

    2023 - 210 on 3/16 shurflo, sap storage shack w/ 1100 gallon tank - 123 gallons
    2022 - 210 on 3/16 shurflo, homemade vac filter & water jacket canner - 104 gallons
    2021 - 215 on 3/16 shurflo, added 2nd membrane to RO - 78 gallons
    2020 - 210 on 3/16 shurflo, upgraded hp pump on RO - 66 gallons
    2019 - 150 on 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 on 3/16 shurflo, 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons

  3. #3
    Join Date
    Jan 2006
    Location
    Oneida NY
    Posts
    11,547

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    For a 2x6 a 4' firebox is more than needed. My 3x8, factory built has a 3' deep firebox, I think most 2x6's will have about 26" to maybe 30" long fireboxes.
    Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
    Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
    Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
    After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.

  4. #4
    Join Date
    Jan 2015
    Location
    Catskill Mts, Ulster County NY
    Posts
    603

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    I can say that 18" is too small. I intended it to be 24", but forgot to allow for the insulation and fire brick. When I rebuild in the off season, I want at least 24" front to back in the chamber. Surprisingly enough, my small firebox works extremely well. The problem is in loading wood. Everything has to go in diagonally, and when you are running AUF/AOF, you don't want the door open any longer than a second or two. So tricky loading slows you down. And unless you are wearing gloves, risks burning the backs of your hands. Definitely will remove the hair. So, I agree with Dave.

    EDIT: I forgot to add the bouncy house blower works great. It's outside in a plywood box, so not heard inside. I also used cast iron barrel stove door (insulted on the inside). Cheap and easy, and holding up well.
    Last edited by Ghs57; 04-04-2019 at 03:12 PM.
    Gary / Zena Crossroads / 42˚ 00' 24" N / Hobby in Early '70s, Addiction since 2014

    175+ taps on 3/16 (60 of which are on two Lunchbox Vac/Releasers)
    12x34 timber framed sap house w/attached 10x34 shed roof for storage
    2 x 6 Smoky Lake hybrid pan on Corsair arch with AUF/steam hood/preheater/concentric exhaust
    7.0 KW Sun Power PV System, Smokey Lake Filter Press/Steam Bottler, Modified NGMP RO - 2 4x40 posts 200 gph

  5. #5
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    634

    Default

    Quote Originally Posted by maple flats View Post
    For a 2x6 a 4' firebox is more than needed. My 3x8, factory built has a 3' deep firebox, I think most 2x6's will have about 26" to maybe 30" long fireboxes.
    Like everything there is varying opinions. I reread several older posts on firebox size and found some say firebox size should be 2/3's for gasification arches (AOF) and others say you don't need that much. And I have heard success on both sides.

    In general theory of gasification arches you need a good sized fire box for everything to mix (gasses and incoming oxygen) and achieve complete combustion before they leave out of the fire box and go up the stack.

    In my opinion it would be better to build the arch frame for the fire box on the large side and if you want to reduce it add more insulation and fire brick.
    Camp Wokanda
    Peoria Park District

    2023 - 210 on 3/16 shurflo, sap storage shack w/ 1100 gallon tank - 123 gallons
    2022 - 210 on 3/16 shurflo, homemade vac filter & water jacket canner - 104 gallons
    2021 - 215 on 3/16 shurflo, added 2nd membrane to RO - 78 gallons
    2020 - 210 on 3/16 shurflo, upgraded hp pump on RO - 66 gallons
    2019 - 150 on 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 on 3/16 shurflo, 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons

  6. #6
    Join Date
    Jan 2012
    Location
    South Dayton NY
    Posts
    18

    Default

    Maple Enthusiast- how many gallons per hour are you able to evaporate?
    2011 12 taps cooked on stove

    2012 150 buckets
    2x6 small brothers raised flue lightning
    Converted corner of old garage for sugar house

  7. #7
    Join Date
    Mar 2006
    Location
    Eden Prairie, MN
    Posts
    1,636

    Default

    My arch started life as a 2x6. It has since been stretched to a 2x8. Like others, I made the firebox a little short. It is about 20" deep and I wish it was 24. I should have stretched it on the front end and fixed that, but I didn't.


    I agree that a bounce house blower is a good idea. Cheap, kind of quiet and reliable. 8" h2o pressure. Mine has been working fine for many years. It works better and is cheaper than the Dayton radial vane blower I replaced. I put mine in an enclosed wooden box so that it is a little quieter and I can shut off air quickly and completely with a simple inlet flapper. No need to mess with a power switch.

    There are many ways to arrange the air system. I use a common outlet for over and under air. The under air doesn't require much pressure so I run that out of the blower and through a blast gate that throttles is desired flow rate. Over fire air is routed without throttling to a manifold that wraps around the firebox. The manifold has lots of cross sectional area so there is little pressure loss by the time it gets to the jets. There, the flow is limited by orifice size. I have 12 jets of about .25" diameter. At 8" of pressure, the jets are around 80 mph so give good mixing. There are some things I plan to change, but as it is, we evaporate at 60GPH and used about 1.2 full cords of mostly hardwood to get over 50 gallons of syrup on 3% sap.
    John
    2x8 Smokylake drop flue with AOF/ AUF
    180 taps on sacks
    75 on 3/16 tubing with shurflo
    Eden Prairie, Minnesota

  8. #8
    Join Date
    Mar 2015
    Location
    Esko,MN
    Posts
    290

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    I built a 2x8 AUF/AOF (page 20 "2x8 arch build"). Photos and Firebox measurements are listed there. My fire box is 54" long. I followed the 2/3 the total length of the pan set but backed off to 54" once I layed out the arch on the floor. I believe I could have cut back another 6"; however, much shorter and I would be throwing wood into the drop flues. Remember to figure in your insulation and fire brick when determining the inside measurement of the firebox. I too use a 1 HP Koala bounce house blower and split my air between the AUF/AOF by using a blast gate and cutting down the AUF and let the rest go to AOF. I used 3/8" black pipe for my AOF outlets in the firebox and capped them and then drilled the caps to 1/4". I get a nice burn and keep my stack temp at 750-900 degrees. I can boil 80 GPH but have a hood and preheater

    .
    Chad

    2014: 12 taps, 5 gal buckets
    2015: 15 taps on bags
    2016: 150 taps: 100 on bags, 50 on 3/16" natural vac, 2x8 AUF/AOF Homebuilt Arch, 2x8 SL Drop Flu & Auto Draw, SL Propane Canner/Bottler
    2017: 225 taps: Built Lean to, Added SL hood, preheater, concentric exhaust, SL SS 7" SB Filter Press
    2018: 180 taps: Added Shurflo to 50 - 3/16", Auto fill sensor to head tank
    2019: No tapping
    2020: 175 taps
    2021: 300 taps, homemade RO and releaser
    2022: 600+ taps

  9. #9
    Join Date
    Mar 2011
    Location
    Live in NY, Sugarhouse in Milton VT
    Posts
    133

    Default

    Quote Originally Posted by 1951oliver88 View Post
    ...

    3. Anyone have a good door design including latch and hinges? Pictures or drawings would be great.


    Thank You
    I made a small arch to use at the end of our season instead of chasing with water in the 2x6 we have (mostly I was looking for an excuse for a first welding project)

    I have some pics of my door
    Someone responded to me - since I had the same question about a door design

    See this thread

    http://mapletrader.com/community/sho...s-descriptions

    A cam lock door is the best way to go IMO
    Having used one on a Leader 2x6 arch before we moved to oil.

    I might be able to find other pics for you

    Here is a Leader arch and door - note that the handle for the cam lock does not cross the door to the frame as someone else posted in one of their pics - the cam lock is what holds the door in place - the handle just has to be set in position to keep the lock in place

    20180315_122351.jpg

    My build:

    IMG_20190204_200309.jpg

    IMG_20190204_200324.jpg

    IMG_20190204_200336.jpg

    IMG_20190205_173312.jpg

    I bought a cam lock trailer door kit from etrailer.com

    Something like this
    https://www.etrailer.com/Enclosed-Tr...re/383200.html
    You have to buy some 3/4" black pipe and weld it up

  10. #10
    Join Date
    Mar 2011
    Location
    Live in NY, Sugarhouse in Milton VT
    Posts
    133

    Default

    There is a limit to the number of pics in one post - so here are two more in a new post

    IMG_20190205_173406.jpg

    IMG_20190205_173326.jpg

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