Electrics

The HERMS brewery is powered by electricity.  At the moment the only controlled part of the system is the heat exchanger.  I use a PID controller and SSR to switch the kettle element on and off in order to maintain a constant temperature in the recirculating wort and hence the MLT.

240vac is very dangerous and you should never mess with it unless you're confident that you won't kill yourself. 

Have a look at this wiring diagram, it will show you how I connected my heat exchanger to the PID controller.  You'll see that I only break/make the live feed to the element with the SSR.  To be sure that the element is completely isolated you could also break/make the neutral with a second SSR.

The SSR I use is a Tyco SSR-240D25 which I bought from RS.  The spec is in the name; it's an SSR used to switch 240 vac, it's switched by a DC voltage and it'll switch 25A.  The element in the heat exchanger is a 2.4kw unit so it'll draw 10A max, so the SSR is well able to switch it on and off safely.

The thermocouple is designed to be attached to a pipe with an attached jubilee clip.  It's a K-type thermocouple and I have attached it to the pipe exiting the heat exchanger.  This is what they look like (in the RS catalogue).

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