Simple Brew Incubator - Setup

NB: To get an overview of related blog posts for this project, please see the Start Page

Main purpose and specs:

The main purpose of the Simple Brew Incubator is to provide a stable atmosphere (i.e. temperature) for beer during the fermentation stage. With the beer I'm planning to make, a temperature of 18-20*C is necessary, but I've set the spec for the incubator have a setpoint range between 4-25*C. I also want to be able to remotely monitor real-time temperature via the web, preferably as a graph. The volume of the incubator should be large enough to hold a tank of ~30 liters, and it should be easily accessible for both inserting/taking out the tank and cleaning purposes. Finally, the incubator and it's controllers must be relatively cheap to purchase and set up.

I quickly made the sketch below to visualize the desired setup (click on image for a bigger version). Section details are described further down the post.

The incubator:

Heat is a bi-product when fermenting beer, so using an old fridge seems logical for an incubator, as it's purpose is already to cool things down. A fridge is also ideal in terms of accessibility and maintenance purposes, and finding cheap used (or thrown away) ones should not be a big issue.

By replacing the existing thermostat with a electro-mechanical relay it's possible to regulate the maximum temperature above the factory settings of a fridge. And by adding a heater element, also the minimum temperature can be regulated. Measuring the temperature in the incubator volume and/or in the liquid itself will provide the regulator with the necessary input, and the heater and fridge compressor will be controlled by regulator outputs. I've also added a fan inside the fridge to get air circulation, hoping to avoid any cold or hot zones.

The control system:

I'm totally aware that there are much cheaper ways of making the control system, for instance you could make it totally analog with very few components. But I have a fascination for the immensely popular and brilliant mini-computer Raspberry Pi (aka RPi), so I've chosen it to be the brains of the system. It can serve as both a regulator using it's I/O-pins and a web application server using the Ethernet-port for connecting to the web. I haven't yet decided exactly what kind of programming language to use or which web applications to install, but I'm looking forward to find out what options are out there. In any case the RPi runs a Linux OS, so that will be interesting as I've primarily used Windows in the past.

With all that in place, it's time to start acquiring the components! Please check in later to how that turns out in the next post :)

-The Engineer-