I live in a small apartment and don’t have room for a fermentation fridge.
Please note, I don’t actually recommend that you build this. I will be working on better designs in the future for temperature-controlled fermentation. This particular project was mostly based around the idea of “could it be done”. This is like a “glycol” system but without the glycol. I’m using plain water but people also use glycol or saltwater instead. My Keezer will never get sub-zero so there is no danger of anything freezing.
How it works
Raspberry Pi runs custom Python code that takes the temp (via DS18B20) of the fermentables and turns on/off power to the USB ports that powers a crappy USB sump pump that is used to circulate cold water from a keg in my Keezer through a stainless steel coil in my fermentor. The Python code is a bit of a mess right now but I will clean it up and put it on my GitHub page eventually.
The power is cut to the USB ports by tricking the Raspberry Pi into thinking the USB voltage is too high by using a compiled binary file hub-ctrl.c. The Pi then cuts power to the USB ports to avoid damaging any plugged-in devices. This allows us to control the pump without the need for an external relay.
The program also logs each event into a CSV file which can be graphed using Excel. Stay tuned for more postings regarding a newer version of this system. I’m be using a single larger pump to control 3 fermenters via electronic valves.
