DIY Electrical Evaporator Design - Page 1

[Cedar Eater]

Edit: The fuse holder mentioned below did not work as a receiver for the heating element terminals. I've left this post in for reference.

I might have just short circuited (pardon the pun) the pan cord issue. I'm looking at a midget fuse block that, if attached at the right height in the bottom of the box, will clip onto the locknuts on the terminals of the heater element when the pan is in the right position. My intent would be to have the power off when setting or disconnecting the pan. I would need to do something similar for grounding the pan, but if this works, I would just use high temp wire between the fuse block and switch. It would make pan alignment more critical, but some spacers mounted on the sides should help with that.

[Cedar Eater]

Edit: I've revised the design since this post was written. The 5500W element was just too much for this pan. I've left this post intact for reference.

I just finished testing the eEvaporator with reworked internal wiring. I removed the pan cord and I have a green ground wire and two high temperature wires running between the pan and the switch now. I also rerouted my 90 degC rated cord through the wood directly into the tunnel for the infinite switch. I intend to leave the previous hole open as a source of cooling air for the switch tunnel.

For the smoke test, I put three gallons of 60 degF water into the pan. The air temp was around 75 degF. I turned the switch to Max and had a roiling boil in 15 minutes. I'm wondering if the boil isn't too vigorous. The water actually got into a rhythm, rolling from side to side but not sloshing out. I let it boil for an additional 15 minutes, turned it off, and let it cool. I measured the remaining water and found it to be only 2-1/4 gallons. That impressed me.

One thing that concerned me is that the infinite switch did not shut off even once during the half hour. I read almost 20 Amps while it was running. That's right at the rating of the wiring and almost 5 Amps higher than the switch was supposed to deliver. I inspected all the wiring and the wooden box and found no indication of overheating. I'll be monitoring to see if 20 Amp wiring should be upgraded to 30. I was a little concerned that the element terminal nuts wouldn't conduct power in to the terminal leads well, but it sure doesn't seem that there was any problem there.

I will edit the initial posts to reflect this design change when I get a round tuit.

[bkeith]

When you turn an infinity switch to Max, it never turns off. Only the settings below Max will cycle on and off. I don't think you'll get a satisfactory boil when it is cycling several seconds on then several seconds off.

Better to use a triac-based power controller, like a massive light dimmer. In another hobby, where they boil things and want to control the amount of power fed to the element, a 120V 15A router speed controller works very well. Sourcing a 240V equivalent shouldn't be hard.

[Cedar Eater]

When you turn an infinity switch to Max, it never turns off. Only the settings below Max will cycle on and off. I don't think you'll get a satisfactory boil when it is cycling several seconds on then several seconds off.

Better to use a triac-based power controller, like a massive light dimmer. In another hobby, where they boil things and want to control the amount of power fed to the element, a 120V 15A router speed controller works very well. Sourcing a 240V equivalent shouldn't be hard.

Thanks. I will look into that. This switch is concerning me as the weak point of the system. I believe that, even though it is handling the current, it might fail prematurely due to the contacts operating at or possibly above their max. If I can't find a suitable controller, I'll switch to a 120V/240V selector switch and increase the wire to 10AWG. The alternative is to decrease the power to <=3600W, which might still boil this pan, but probably nothing larger.

Edit: I couldn't find a way to add a Triac based controller to the system cheaply. If anybody has one they can recommend, please let me know. Otherwise, I've revised the design to a specific wattage of heating element, 4000W that draws less than 20 Amps and supplies a less boisterous boil.

[Cedar Eater]

I decided to test this box with a 4000W heating element and I'm liking the results a lot more. The boil took only 5 minutes longer to achieve and it is not as vigorous, but there was no visible splashing of tiny drops outside the pan edges as there was with the 5500W element, and it appears to be more than good enough. If that turns out not to be the case in cold weather (which I believe is highly doubtful), it will be possible to upgrade to a 4500W heater element without compromising the rest of the new design. Because of the extra five minutes required to achieve the boil, I let the three gallon test go for 35 minutes instead of 30. The amount of water remaining after the cooldown was only slightly more, still in the neighborhood of 2-1/4 gallons.

With the decreased vigor of the boil, the need for controlling the element went away. This pan will be used for evaporating sap, not finishing the syrup and because of the amount that must remain in the pan to keep the element covered, there is no reason to use it as a warmer. A simple on-off switch is cheaper and I believe safer and more reliable than the infinite switch, so I'm going with that and removing the infinite switch from previous posts. If you really want to use the pan as a 2-4 gallon warmer, the addition of another switch, a 3-way 20 Amp switch would allow you to drop the voltage across the element to 120V and reduce the power drawn to 1000W, by switching the neutral wire to the element instead of the L2 wire. Note: To do this you will need to upgrade the plug and cord to a 4-wire L14-20 and have a source that is 4-wire 120/240 instead of 3 wire 240. There's a way around that, but it isn't pretty.

During the test, the current read only slightly over 15 Amps, which is near to the 16.667 calculated for 4000W at 240V. So I will be installing a 2-pole 20A switch in a surface mounted box. This will remove the need for a cord rated at 105C, so the cheaper 90C cord that I originally specified will suffice. I will shorten the specification to a 6' cord because the pan cord has been replaced with separate insulated wires.

[bkeith]

This should do it. http://www.ebay.com/itm/LED-Display-...item339054b3c5

or this http://www.ebay.com/itm/New-4000W-AC...item3cd04414bd

or this http://www.ebay.com/itm/New-AC-220V-...item33a18ca886

or this http://www.ebay.com/itm/10000W-220V-...item3cf6f487d8

To name a few. There were many more, in different configurations.

All seem economical and easy to integrate. I'd probably go with one of the 10kW units so as not to be pushing it to the max.

[Cedar Eater]

This should do it. http://www.ebay.com/itm/LED-Display-...item339054b3c5

or this http://www.ebay.com/itm/New-4000W-AC...item3cd04414bd

or this http://www.ebay.com/itm/New-AC-220V-...item33a18ca886

or this http://www.ebay.com/itm/10000W-220V-...item3cf6f487d8

To name a few. There were many more, in different configurations.

All seem economical and easy to integrate. I'd probably go with one of the 10kW units so as not to be pushing it to the max.

Thanks, I like those. I didn't find anything near that cheap when I searched. I think I'll buy one for my In-Sink-Evaporator, where I think it will be much easier to integrate. The In-Sink-Evaporator is 33% larger in surface area, twice the liquid volume, and has a bottom drain, making it more likely that it would need a variable boil. I'm a little concerned about using these controllers outdoors for this design. I plan for my area to be sheltered from falling rain and snow, and I'm not planning to have raintight switches, but fog, wind-driven mist, and condensate from the boil are a concern. These don't seem to be suitable for mounting inside the box due to the heat, or on the side of the box due to the lack of protection of the components and the need to keep them well ventilated. I'm trying to keep this design simple enough to easily replace the propane burner option, so building a weather-tight instrument panel for the controller is no small matter. I wish I could cheaply simulate the conditions of late Winter - early Spring on my deck to verify that 4000 - 4500W will be enough for the steam table pan, but I'm confident enough that I think I will just stick with the on-off controls for it.

[Cedar Eater]

I've finished editing the first three pages after the failure of the fuse block. It is now in syrup production and I am watching all the connections for signs of overheating and insulation failure.

[TrapperX]

You have inspired me! Are we getting close to a real world test with sap

I am looking at this Titanium one and have a 19x11x6 pan.
Plans would be to build an insulated box for it.
Have you thought of any thing else you would improve on?
Posting this real quick on my way out to tap a few more trees before dark.


http://www.amazon.com/gp/product/B00...=sr_1_2&sr=8-2

http://www.amazon.com/gp/product/B00...A2OCOGC9B25845

http://www.amazon.com/SMAKN%C2%AE-0-...dulator+10000w

[Cedar Eater]

You have inspired me! Are we getting close to a real world test with sap

I am looking at this Titanium one and have a 19x11x6 pan.
Plans would be to build an insulated box for it.
Have you thought of any thing else you would improve on?
Post this real quick on my way out to tap a few more trees before dark.


http://www.amazon.com/gp/product/B00...=sr_1_2&sr=8-2

http://www.amazon.com/gp/product/B00...A2OCOGC9B25845

http://www.amazon.com/SMAKN%C2%AE-0-...dulator+10000w

I'm real close to testing it. All I need is sap. I haven't made any other changes. I left it sit outdoors all year to see how it would weather. It passed that test.