Incremental BrewPi DIY Project

Hello brewers! I was lucky enough to get a home brew starter kit for Christmas, and I’m waiting on my first batch of Young’s American IPA conditioning - just about drinkable at the moment but hopefully will end up decent enough after a few more weeks.

Since I had a spare Pi and Arduino around and I’d heard of BrewPi, I thought I’d have a go at building a controller (which has been just as fun as the brewing!). After getting hold of some probes from eBay and doing some tinkering, I’ve managed to get a basic BrewPi setup working which is currently monitoring the tail end of my IPA in its pressure vessel. So, depending on the success of my brewing, I’d also like to build out my controller capabilities as I go. Here’s the rough plan:

Phase 1 (complete!):
Pi 2B and Arduino UNO clone, 4x20 I2C LCD with brightness control, 2x OneWire probes. Temporarily housed in a plastic takeaway box.

Phase 2 (components en-route):
Add 4x 10A relay shield, fit M12 connectors to probe wires, transplant to proper ABS enclosure. Add heater pad connected to relay.

Phase 3:
Transplant to fridge, depending on availability of fridge and some space to keep it.

Phase 4:
Should I find I can brew competently down the line, maybe one of Elco’s fancy new Spark BrewPi controllers.

For the next brew, I was just going to add a heating pad to add some basic control for temperature (can hopefully get away without cooling for now). I’ve loads of spare IEC cables, so I was planning on using one or more of these with a panel mount socket or two to connect to the heater/power (going to use an RCD plug I have there).

One thing I’ve been wondering about is the wiring for the relays. I’ll only have the one heater to control initially, but was planning on future proofing the connectors so I can relatively easily connect to a fridge in future. I was looking at the FuzzeWuzze guide on home brew talk and basing the wiring off the basic schematic:

Slightly different sockets given my power is UK instead of US and I wasn’t going to hack an extension strip directly. Could I get away with using one 3-core cable to 2 relays - one live and using the other two wires to switch the neutral? Can use two cables for the heater/fridge respectively but would be neater to use the one.

Was thinking of hooking up the power/RCD to the relays and heater using a 4-way junction box like this (which I’d hope would leave a space for fridge?):

Does that make sense? Perhaps over/underthinking the circuit.

Shall update on progress in the next few weeks.


I don’t understand what you are trying to do with your wiring. You should always switch the live. I am also in the UK and have two single sockets in a back box (a twin that is designed for two single sockets).

Thanks rpt. I would have assumed switching the live would be better, I was just going on that diagram I referenced, but perhaps I misread it. Using a twin UK backbox is indeed a good idea and just remembered I have an unused outdoor one kicking about that I can use, and would be much simpler than what I had in mind. Cheers.

The diagram you referenced also switches live!

It does indeed, I think the colours used threw me and I didn’t look at it closely enough. Got my sockets just about sorted, just waiting on my relay board and enclosure to get everything connected up in its permanent home, then I can test out control.