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Thread: DIY Electrical Evaporator Design - Page 1

  1. #1
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    Default DIY Electrical Evaporator Design - Page 1

    I couldn't let well enough alone, so I made a bare-bones electrified evaporator with an immersed 4000 Watt spa heating element in a steam table pan with a simple 2-pole 20 Amp light switch. I'm calling this new frankenboiler an eEvaporator. My general philosophy when making prototypes is, "Better is the enemy of good enough." This frankenboiler won't win any beauty contests, but it will safely boil sap.



    I have sufficient outdoor 240 Volt power available to run this and the In-Sink-Evaporator. The combination gives me about 3.5 sqft of boiling surface area, with 1.5 of that from the eEvaporator. Next Spring, I'll be able to do some side by side comparisons, but I mainly did this to make a simple-enough DIY project so that others who are interested can build a cheaper-than-propane method of making syrup. My goal was to make a 240 Volt appliance that is safe enough for outdoor operation in the maple sugar season, assuming that you use reasonable precautions, like wearing rubber-soled footwear and unplugging the pan when boiling is finished.

    The Outdoor Evaporation Area

    It may seem tempting to dismiss this project due to a lack of 240 Volt power outdoors at your home. I am qualified to do my own work on this front, but you may have to find a relative or friend with appropriate experience who will work for syrup. The amount of power that you have available will determine how many of these electrified steam table pans that you can operate, so before I get into the building instructions for the pan, I'll throw out some ideas you can use to get power out to a sap boiling area.

    Of course, anything you can do to help make the sap cooking area reasonably dry and sheltered from rain and snow will help. I fastened a tarp under the soffit of my home's roof and sloped it out to the handrail of my deck in order to give myself some protection from the elements. A covered patio, carport, or even a screen tent may be an option. Unlike with propane, you don't have to worry about wind. Wind is your friend because it moves vapor away from the liquid surface.

    240 Volt Power Options You May Not Be Aware Of

    Most homes come with some dedicated 240V circuits that might be useful so that you will not have to install a new run back to your breaker panel. If you have a standard RV hookup, an electric smoker, or a pool, spa, or hot tub outdoors, you may have some possible options. I have a spa on my deck. It has a 50 Amp feed from the main breaker panel to a fused disconnect box that by law has to be located within sight of the connection point at the spa, which is under the deck. I fed the power from the fused disconnect box into a new outdoor load center (breaker panel) and installed one 50 Amp two-pole breaker for the spa and one for a receptacle for a range that has been re-purposed as a smoker. I can use the smoker receptacle for my eEvaporator and In-Sink-Evaporator. I can minimize the power requirement of the spa during the sap boiling season.

    Garages, barns, or shops can be another source of power. If you have a welder outlet or any other 240 Volt plug-connected equipment outlet in your outbuilding, you can use those with appropriate extension cords. If you have a subpanel in an outbuilding, a new circuit from there might be cheaper than a new circuit from your house.

    If you have 240 Volt power routed through an unfinished basement or crawlspace to a range, water heater, air conditioner, or electric dryer, this gives you an opportunity to tap into those circuits and save some money on installation. The installation may not be "up to code", which normally requires dedicated circuits for each 240 Volt appliance, but the building code is there to protect people from contractors who would cut corners. A homeowner who is willing to live with a little inconvenience, like not being able to run their clothes dryer while boiling sap, is simply practicing load management. Adding another receptacle to that circuit to utilize it for another purpose is not unsafe.

    A small hole can be drilled through the side of your home to feed a cut extension cord through, and then a new end can be installed on the cord and plugged into your dryer, air-conditioner, or range receptacle. For each eEvaporator, you'll need 16.667 Amps of 240 Volt power. I recommend a NEMA L6-20 power cord for outdoors. They have 20 Amp twist-locking connectors rated for 250 Volts.

    Of course, if your circuit breaker box is handy in a location where adding new circuits doesn't require much renovation, new circuits from it with all the appropriate permits and inspections are certainly advised, but not necessarily safer than the alternatives. The savings over propane for boiling sap are significant, but doing things "the right way" can be very expensive.

    How To Build An eEvaporator

    I'm going to assume that anyone who can use a hammer, drill, pliers, wrenches, screwdriver, wire cutters, knife, and circular saw is qualified to build this.

    Materials list:

    1 - Deep (6" minimum) full-size steam table pan
    1 - BX5000C 4KW Universal Heating Element
    1 - 20 Amp Double Pole switch
    1 - Simpson Strong Tie 3" X 5" tie plate
    1 - 6' NEMA L6-20 extension cord or 6' of 3 Wire 12 AWG flexible cord and a NEMA L6-20P plug end, or, if you think you will want to switch the heater element down to 120 to use the pan as a warmer, 1 - NEMA L14-20 extension cord or a 4-wire 12AWG cord and L14-20P plug end
    1 - 2m high temperature lead wire
    1 - light switch box of your choice (raintight if you think you need it)
    1 - 1 X 8 X 10' or 2 X 8 X 10' board
    2" or 2-1/2" wood screws (depending on which board you use)
    Crimp-on wire terminals


    It takes over six quarts of liquid to immerse a spa heater element installed at the bottom of a full-size pan, and you don't want to run the element dry. If lifting the pan to dump that much liquid seems like it would be too heavy, you can scoop out some of the concentrated sap before dumping, or install a drain valve for the pan. I'm trying to show a minimal cost project, so I'm not including a drain valve. You might be tempted to use a shallower pan to minimize cost, but a shallow pan will have more problems with overflow and splashing than a deep pan.

    Hold the element lengthwise in the center of the bottom of the pan and note where the terminals for the element will contact the pan. I think it's better to run the element lengthwise to minimize overflow and splashing. This is how the pan looks when water is boiling in it.



    Note that the terminals do not line up perfectly along the imaginary centerline of the pan and are not perfectly centered in the element. In order to center the element, you will have to offset the holes for the terminals. A rough approximation is sufficient. I used a Sharpie to mark where the first hole would be best, and after placing a sacrificial block of wood under the pan, I used a hammer and a 20D nail to punch a small hole in the bottom of the pan. I measured 1-1/4" from that hole, offsetting the tape slightly, and made a second hole.



    I used a set of titanium drill bits to expand those holes out in small steps to the 1/2" diameter required for the spa element. Taking small steps (1/32") gives you the opportunity to adjust the centers of the holes to ensure that they are precisely 1-1/4" apart when the final 1/2" hole diameter is reached. Aiming the drill slightly toward the other hole when drilling will move the centers closer together and aiming the drill slightly away will move them apart. When finished drilling, it may be necessary to debur the edges of the holes with a round file to get the terminals to fit through them. This is how it looks when they are ready for installation of the element.



    Continued on Page 2
    Last edited by Cedar Eater; 03-13-2016 at 02:19 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  2. #2
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    Default DIY Electrical Evaporator Design - Page 2

    You're not done drilling metal yet, but now the metal will be softer. This step is optional, but I highly recommend it. In my opinion, it is too risky to rest this pan on its terminals, and whenever it's out of the box, that could be a problem. They are not designed to be load bearing. So to protect the terminals from bashing in the future, the Simpson Strong-Tie plate will become a guard for them. Once this guard is installed, setting the pan down on its bottom will risk scratching the surface you set it on, but setting it on its terminals would risk the same and would also risk breaking them. So drill holes in the plate so that it will fit over the terminals as shown.



    Bend the plate as shown below. I used pliers to start bending the plate at the second row of holes from the top and bottom and then hammered the plate around the edge of a 2X4.



    The next steps are to support the pan in a frame and provide power to it. You could simply set the pan on wooden sleepers on the ground, but it will lose heat if it's not enclosed and insulated, and you would have to find a way to safely wire it. A standard steam table pan fits into a hole that's 12" by 20". That gives the pan a little room to grow when it gets hot. The easiest durable-enough frame for me to make was a box made from 1 X 8 boards and wood screws. Wood serves well enough to insulate, but a box could be oversized and then lined with rigid board insulation and even aluminum foil to make it better. There would be no need to make it deeper, because there is room under the pan for an inch of insulation, except near the terminals.

    I notched opposing corners in the box to make it easier to lift the pan out to pour the concentrated sap into a pot for finishing. I'm right handed, so I notched what would be the nearer left and farther right corners (when considered from a long side), because this seemed the most comfortable for pouring away from my feet out the farther left corner.



    The early design included a fuse block being used as means to plug the pan into the base. The fuse block did not work out because the terminals of the heating element get too hot, so the fuse block has been removed from the design. Simply hard wire the leads with the high temperature wire and crimp-on ring terminals.

    Continued on Page 3
    Last edited by Cedar Eater; 03-13-2016 at 02:29 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  3. #3
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    Default DIY Electrical Evaporator Design - Page 3

    Before I go further, I want to emphasize that my plan is to always unplug the power from the source before lifting and pouring the concentrated sap out of the pan. If built according to this design, there should be no danger of electrical shock, but boilover and spillage are variables where it doesn't hurt to make sure the equipment is unplugged whenever boiling is not intended. While boiling, I wouldn't recommend routinely touching the heating element with a strainer while scooping foam, but it shouldn't be dangerous.

    The initial design of this prototype contained an infinite switch for controlling power that just isn't necessary or even useful when the wattage is kept within the range that's reasonable for a steam table pan. So I've simplified the design to use a simple 2-pole on-off switch matched to the wattage range.

    The next steps are to mount the switch and wire everything. I used a double wide metal box, in case I ever want to mount a second switch for dropping the voltage to 120, but really because I just happened to have one available. I connected a 4' ground wire from the guard of the heater element terminals to the ground connection inside the switch box. This keeps the box grounded in case you forget to turn the power off when you lift the pan, but it also limits how far you can move the pan from the box. I used high temp wire to connect the fuse block to the load side of the switch and connected the cord to the line side of the switch.



    This is about as basic as I can imagine for a safe outdoor 240V appliance. I'll let you know if I encounter any problems with it.
    Last edited by Cedar Eater; 06-06-2015 at 02:33 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  4. #4
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    I looked at your plans just out of curiosity, since I have a 3x8 wood fired rig, but I have a question. What is the temp. rating of the wire under the unit? Since you will be boiling up to 219 or 220, you will want that wire to be rated for higher temps. Most extension cords are not.
    For those looking to make something like this, be sure the wire(s) used under the unit, where the heat will easily reach 220, are rated for those temperatures. They will usually be stated on the cord jacket in Celsius. You will want wire rated at over 105 or the insulation on the wire will break down and eventually fail, possibly causing a short (or worse).
    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/
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  5. #5
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    Quote Originally Posted by maple flats View Post
    I looked at your plans just out of curiosity, since I have a 3x8 wood fired rig, but I have a question. What is the temp. rating of the wire under the unit? Since you will be boiling up to 219 or 220, you will want that wire to be rated for higher temps. Most extension cords are not.
    For those looking to make something like this, be sure the wire(s) used under the unit, where the heat will easily reach 220, are rated for those temperatures. They will usually be stated on the cord jacket in Celsius. You will want wire rated at over 105 or the insulation on the wire will break down and eventually fail, possibly causing a short (or worse).
    Edit: I've revised the design since my original response was written. Thank you maple flats for inspiring me to think of better internal wiring.
    Last edited by Cedar Eater; 06-04-2015 at 05:48 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  6. #6
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    Edit: I've revised the design since this post was written. I'm just leaving it in for reference.

    Update on the cord rating:

    The cord that I specified, 12/3 Type SJOOW, is rated at 25 Amps at 90degC instead of the 20 Amps I was assuming. A better cord would be 12/3 Type SJTOOW, but operated at 15 Amps, I'm pretty confident that the Type SJOOW will perform well, except possibly right at the heater element terminals. Inspect it there when dumping the concentrated sap and replace it with higher temp wire if it shows signs of melting.

    Further update on the cord rating:

    A conflicting source claims the 25 Amp rating of Type SJOOW cord is for 30 degC, implying that the 90 degC rating is an absolute rating independent of the current. Unless I can find and link to a source of SJTOOW cord, I will switch to high temp lead wire and change previous posts to reflect that.

    Further update to the cord specification:

    I changed the cord spec in the materials list to a Type SJEOOW, which is rated for 105 degC. Since it will be operated at 15 Amps, and since the pan is for reducing sap to nearup and not for producing finished syrup I think the box temp will not exceed the cable rating. If it does, I would expect degradation to show up first at the terminals of the heating element. If I saw that, I would replace it with high temp lead wire.
    Last edited by Cedar Eater; 06-04-2015 at 03:55 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  7. #7
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    Another consideration along with the quality of the cord is the breaker. If that element is only pulling 15 amps, be sure to only have it hooked up to a 15 or 20 amp breaker. Reason is that if for some reason that element did run away on you or went dry, that cord will burn up with too high of a rated breaker before it will ever pop. Always match your protection to your appliance needs as well as the cord. Breakers are usually pretty easy to change out, even if temporarily.
    220 Taps
    2x6 Home made
    Sap Shack 20x20
    5 Shurflo diaphragm pumps
    250 GPH Deer run RO

  8. #8
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    Edit: I've revised the justification used below because the infinite switch initially used with this design is removed from the system.

    Quote Originally Posted by Waynehere View Post
    Another consideration along with the quality of the cord is the breaker. If that element is only pulling 15 amps, be sure to only have it hooked up to a 15 or 20 amp breaker. Reason is that if for some reason that element did run away on you or went dry, that cord will burn up with too high of a rated breaker before it will ever pop. Always match your protection to your appliance needs as well as the cord. Breakers are usually pretty easy to change out, even if temporarily.
    That's not really required and isn't even considered to be good design practice. It's a common misconception that it's the function of circuit breakers to protect against the failure of plug connected loads. The circuit breaker's function is to protect the wire and cable routed to the outlet through the home from overload and downstream short circuits, not from downstream overloads that put cords at risk. Houses are full of 20 Amp breakers feeding power to plug connected loads that have cords rated for 10 Amps (or less) through receptacles rated for 15 Amps. That covers many of the lamps in your home.

    With plug-connected loads, the nature of the load is its protection against overload. Heating elements are very reliable and are already very low resistance. That's why they don't even put a "red button" device on coffee makers and crock pots. When they fail, they almost always fail open, and when they don't, they quickly short circuit and trip the first upstream breaker, which is the function of the home's circuit breaker. No additional circuit breaker or fuse is required, but it wouldn't be hard to add a fuse inside the box on one or both of the leads to the heating element if you want to play it safe. A fair criticism of this design is that it does not protect against high temperature resulting from dry fire of the element. If anybody has any ideas about that, please contribute them.
    Last edited by Cedar Eater; 06-04-2015 at 04:29 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

  9. #9
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    Might it be worth considering adding a layer of Roxul for the pan to set into? Maybe the thickness of the Simpson thingy? Would serve to keep heat in the pan, and away from the rest of the components.

  10. #10
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    Edit: I have since revised the design so that it does not have a cord between the switch and the pan. I like the idea of having insulation of some sort under the pan. I'm leaving the original post intact for reference.

    Quote Originally Posted by Mel View Post
    Might it be worth considering adding a layer of Roxul for the pan to set into? Maybe the thickness of the Simpson thingy? Would serve to keep heat in the pan, and away from the rest of the components.
    That would be great if it didn't interfere with lifting the cord out to dump the pan. I guess it would have to come out with the pan so the cord could coil beneath it. I tried to find a spring clamp mechanism to mount to the bottom of the box that would grip the heater element terminals when the pan was set into them, similar to the way some stove burners plug into a receptacle under the stove top. That would remove the necessity for a pan cord. I just didn't find anything that was designed to grip the spa element terminals. If anybody has any ideas on that, I would be happy to add that to the design.
    Last edited by Cedar Eater; 06-04-2015 at 04:33 PM.
    CE
    44° 41′ 3″ N

    2019 -- 44 Red Maples - My home and sugarbush are for sale.
    2018 -- 48 Red Maples, 7 gallons
    2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
    2016 -- 55 Red Maples, 8 gallons
    2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
    An awning over my deck is my sugar shack.
    An electrified kitchen sink and an electrified steam table pan are my evaporators.

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