After homebrewing for so many years, I knew fermentation temperature control was something that ought to be added to my capabilities. I’ve made controllers from the STC-1000 box but the BrewPi was attractive for the detailed control offered and logging abilities, and it seemed like a neat challenge.
I ordered the parts from BrewPi in Europe but decided to omit the pretty enclosures offered by the creator, Elco, as I wanted to get everything in one box to the extent possible. The supplies from BrewPi included two nice solid state relays, LCD display, temperature sensors, and parts to solder up the Arduino shield (an easy soldering job). I ordered the Raspberry Pi and a WiFi dongle for it, plus the Arduino, separately from Adafruit.
I decided to power the Pi and Arduino through this pluggable brand USB powered hub, which also connects the devices for data. This worked well in my first tests show below, where I got the temperature sensors working to control the SSRs though the BrewPi software.
I ordered this box to use as an enclosure, which is a little larger than necessary but not massively so. It held everything (including the power supply for the USB hub, fused IEC power inlet and switch, and AC outlet for heating/cooling) with some room to work, and is nominally waterproof (NEMA) but that is not something I plan to put to the test, especially after I made holes for the sensors, display, etc.
The temperature sensors are on a neat three wire digital bus. I used old mint tins to house the distribution boards as you can see in the below photo, showing lines for the fridge and beer temperature sensors. The right carboy has a thermowell to get the beer temperature sensor into the mass of the beer. There is no heater connected, as I didn’t think it would be particularly necessary and I didn’t want to compromise the seal on the refrigerator to pass the AC power cord. There is a separate room temperature sensor outside the fridge simply to log room temperature.
Below is the data showing the fermentation of this English Bitter style ale. There is a lot of information there, but I find it clearly presented. The orange line for refrigerator setpoint jumps around at the beginning as the PID algorithm works to find the right temperature to reach the target beer temperature, which I started at 66F but then reduced to 64F shortly thereafter. You can see the fridge temp converge with beer temp near the end as fermentation slowed and stopped making significant heat. The beer temperature was rock solid the whole time within +/- 0.1F. The beer tastes great and I’m very happy with the BrewPi.