Rudimentary power control on keg boiler...

[zed255]

Folks,

I am going to be using a 15.5 gallon keg as a boiler on my still. I installed two ports for my heating elements which are currently 230V 3000W units. I was going to simply use switches to run my elements independently on any combination of 230V, 115V, or off. This would allow power to be:
6000W if both elements are in parallel on 230V
3750W if one element is on 230V and the other is on 115V
3000W if on element is on 230V and the other is off
1500W if both elements are on 115V and finally
750W if one element is on 115V and the other is off

My question is wether the available combinations allow enough control or not. I of course have the option of choosing different wattage elements to alter the available power combinations available. I ask this after seeing the stunning myriad of threads on various phase controls. Is anyone doing similar to the above?

[StillerBoy]

Yah you can always run the still with the options you mention.. but.. why not build a controller for better control.. Install two 5500 watt elements.. one on 240 and the other on 120.. at heat up, use both.. once at temp, disconnect the one on 120, and operation off the controller which is connected to 240v..

A simple controller such as this is not hard to put together and gives you precise control..

Mars

[shadylane]

Sounds good to me
I have a controller, but seldom need to use it.
One advantage of using constant power, is repeatability
posting with sb

[NZChris]

You don't say what you have stacked on top of it.

I can run my 9 gallon pot still well enough with 3000W, 1500W & 750W, using two 1500W elements, but usually opt to use a controller on one element.

[zed255]

You don't say what you have stacked on top of it.

I can run my 9 gallon pot still well enough with 3000W, 1500W & 750W, using two 1500W elements, but usually opt to use a controller on one element.

Well I guess what it will be driving vapour through matters. The current build is 3' of 2" packed column into an offset head with a 12" long 3" diameter dual layer + cold finger condenser.

I suppose the real question is how much control is really required assuming one can live without tuning for maximal throughput, that is possibly sacrificing some efficiency if the available steps in power don't land near the ideal setting.

[cranky]

Personally I don't see the need to run multiple elements in a 15.5 gallon boiler, much less complicating it with different switching. I run a 15.5 keg with 5500W element and it works fine. A simple controller is pretty easy, quick and cheap to build, probably easier and maybe even cheaper than wiring up switches to do what you want.

[zed255]

Two elements are already installed. Perhaps it is not necessary but I went that way because I did not find a 5500W (popular wattage from my reading here) element locally and thought two readily available 3000W would do as a substitute.

It only came to mind about using simple switches, two for ON-OFF of the elements and two for voltage selection for each element. In cruising through the forum I did not really see this approach discussed and thought I'd get some opinions / ideas. Certainly putting together a big light dimmer (or sourcing a ready made module) is not out of the question, but given to simplicity of a couple switches per element I just had to ask.

I was more curious if the idea was practical or not and if anyone has had personal experience running their rig that way.

[kimbodious]

Check out the link to my power controller in my signature. You can get similar cam switches with even more poles for more options. Mine only has 3 settings, [1] On (no controller), [0] Off, [2] On (using controller)

[NZChris]

The only reason it wouldn't work would be if an ideal Wattage wasn't available. To work that out, I would run the still with a controller on one element while keeping records. if it turned out that the ideal Wattage wasn't available, I'm sure you could make it available by running combinations of elements in series and parallel, but don't ask me to design you a user friendly way of doing the switching, cos that is just way too much trouble.