OK, so I thought I would update this thread with some upgrades I've done since finishing my original e-brewery build. The first addition was a HERMs coil I built into the HLT keggle. I used the SS coil from a spare 25' immersion chiller I had bought from NY Homebrew supply and SS parts from Bargain Fittings.com. I accidentally kinked one section of the coil, but was able to fix it. The HERMs works great.
This week I built a PWM circuit from Bakatronics following the instructions in this thread
. Here's the circuit:
Then I built it into my control panel. I needed a 12 volt power supply
and a 4 pole double throw switch
for the PWM circuit, both of which I found for pretty cheap at AllElectronics.com.
I have 1 pole of the 4 pole element selector switch controlling 120VAC to the contactors, 1 pole turning on the indicator lights, and 2 poles switching the 12VDC legs between the PWM circuit and the PID controller, so that the SSR is run by the PID when switched to the HLT, and the SSR is run by the PWM circuit when switched to the BK.
Here's how it looks in the panel - the PWM knob is on the top row between the E-stop and the power LED:
I mounted the 12VDC power supply to the top inside of the enclosure using a big piece of adhesive velcro. Here's the guts of the panel:
I've done some testing with it with only 120VAC wired into the panel just to test the PWM circuit and the new switch. Everything seems to work great - the SSR LED barely blinks at all when the PWM circuit knob is turned to Lo, and is on about 98% of the time when the knob is cranked to Hi.
I won't do a full power test for a while though, since I've shut down the brewery for the summer. I've got too much beer to drink, and it's too hot to make more.