Being an avid homebrewer, I have learned fermentation temperature control is crucial to make good beer. Luckily with the help of an Arduino Uno, Raspberry and BrewPi software this is easily accomplished. BrewPi has released an all in one solution for fermentation control but being the Do-It-Yourselfer I am I decided to build one myself.
How It Works
My fermentation controller is composed of a RaspberryPi, used as a web server and to display UI, an Arduino Uno micro-controller for relay control and I/O signal processing, and temperature sensors (x2) to read the temperature of beer and drink cooler.
The BrewPi software is installed on the raspberryPi server and allows you to set a temperature profile and upload it to the Arduino Uno. This controls the temperature of the fermentation chamber, in my case a drink cooler, using signals sent from the temperature sensors. Having one temperature sensor inside the beer fermenter and one sensor reading the temperature of the fermentation chamber allows the Arduino to act as a PID controller. It will turn on and off a heater or the drink cooler to adjust the temperature of the beer and keep it within a degree of the set temperature. Since the beer heats up during fermentation, keeping the temperature consistent without using a system like this is nearly impossible. Keeping the beer in specific ranges during fermentation is crucial because if the beer gets too hot or too cold you risk off flavors in the beer.
Setting up a fermentation profile is pretty straight forward using the BrewPi software. I usually set the temperature in the mid 60s for the first 4 or 5 days of fermentation when the fermentation is most active, then bring the temperature up slowly to ensure all of the sugars in the wort (fancy name for beer before it becomes beer) are converted to alcohol. Then I “cold crash” the beer at a temperature in the 30’s to help the yeast settle to the bottom (flocculate) of the fermenter, this makes the beer crystal clear and prepares it for its transfer to the secondary fermentation phase.