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Voltage controller with an urn?

PostPosted: Wed Sep 05, 2018 2:42 pm
by Hefty
Hi all,
This relates to a question I had in my intro/welcome post the other day.
I have a 40L 2400w exposed element urn that I've got rigged up for mashing (I'm a beer brewer from way back) using an STC-1000 for temp control.
Now, having done some more reading on here, I understand that this sort of controller isn't suitable for running a boiler.
However, if I can rig it up as a pot still and get a good seal around the rim then can I get/build a voltage controller for the urn, if I set its internal thermostat to full? or do I absolutely HAVE to bypass the internal thermostat circuitry to control its voltage?

Cheers,
Jono.

Re: Voltage controller with an urn?

PostPosted: Wed Sep 05, 2018 11:11 pm
by PeterC
Hi, Controllers that use a thermostat usually switch on/off around the temperature set point. Voltage controllers modify the voltage to run at a fixed value. This means you can supply a steady power level which in turn creates a steady rate of vapour production. You set the controller to give the rate you want. In a pot still you control the rate of production. In a bubble plate still you control the amount of reflux that is happening. Too low and you get low reflux or the plates may not load up. Too high and you may push past the reflux condenser or get plate flooding. It is great to have the control to run the still at a the right balance and every still is different.

You could maybe still use your boiler. Just leave the internal thermosat to full but get an external voltage controller which fits on the power lead to the boiler. I am not an electrician so I could not comment if the voltage controller would affect the thermosat electrics.

Re: Voltage controller with an urn?

PostPosted: Thu Sep 06, 2018 5:12 am
by JayTee
I use a voltage controller in the way that PeterC suggests very successfully. No issues at all with the boiler thermostat

Re: Voltage controller with an urn?

PostPosted: Thu Sep 06, 2018 5:52 am
by JayTee
I should add that you don't want the urn thermostat triggering during distillation, so its temperature threshold should be raised accordingly.

Re: Voltage controller with an urn?

PostPosted: Thu Sep 06, 2018 12:13 pm
by username
I use a crown urn with concealed element for BIAB.
I have not modified the thermostat, and have measured (admittedly questionable accuracy) 110 degrees on full rolling boil, i haven't had the thermostat kick in.
I wouldn't expect a wash boiling off alcohol to have a higher rolling boil temp than malty water.
I suspect you are better off the leave the thermostat unmolested and check what temp it kicks in at?

Re: Voltage controller with an urn?

PostPosted: Thu Sep 06, 2018 12:37 pm
by warramungas
Set your urn to full noise and use a voltage controller to supply the power to through its normal plug. I used a birko for years this way with a sutronics burst fire controller and if that didn't blow it up one if these more modern jobbies wont.
And you're right. An stc1000 is completely wrong for it. Its basically an electronic thermostat which the urn already has.

Edit: Keep in mind though I had a nightmare of a time sealing mine though.