This project deserves an A++ for making something related with beer! As I am gulping a Budweiser 40 down my throat, I find this email in my inbox about HOWTO make a Arduino Beer Thermostat! Cool… Keep up the great work David and thanks for the tip!
I belong to a diverse group of amateurs who have a fascination for brewing our own beer. In addition to the satisfaction of brewing the beer I drink, and the control I have over the process (and the ability to easily avoid crappy mega-swill beer from the big breweries), we homebrewers get to play with a bunch of cool gadgets. Even if you don’t have any interest in cooling beer, this information in this tutorial can be applied to other projects that involve analog sensors, and high-voltage/current devices.
Over the past few months, I’ve started kegging my own beer, at home. This is a pretty simple process, but one of the key ingredients to making consumable draught beer is temperature control. Obviously, beer doesn’t taste quite as good if it’s warm (or too cold, for that matter), but there’s more to it: carbon dioxide is much more soluble in water (or beer) at lower temperatures, so it’s essential that kegs be kept cold, when serving.
Most homebrewers take one of three approaches to cooling their beer: buying a pre-made kegerator, gutting a regular refrigerator to hold kegs with taps on the door, or altering a chest freezer to hold the kegs and mount taps. I chose to take the third approach (a friend was getting rid of a near-perfect sized chest freezer).
Generally, chest freezers have thermostats that work in the “freezer” range. That is, below 0ºC, or below water’s freezing point. Even at the “warmest” temperature, most freezers will still freeze beer. This is no good when it comes to kegerators. Many homebrewers solve this problem with a device referred to as a “Johnson,” “Love,” or “Ranco” controller (depending on the brand of controller). Basically, this device plugs between the AC mains and the chest freezer, and has a temperature probe that is placed in the freezer (the freezer’s internal thermostat is set at “maximum cold”). The temperature probe, depending on the model chosen, will either be a solid/liquid mechanical probe (usually found on the cheaper controllers–this is likely the same type as is found on the freezer’s internal controller), or a thermistor.
One day, a few weeks ago, I had the urge to finally get my chest kegerator cooling my beer. Living in Canada has its benefits, but one of the recurring problems we Canadians face is the difficulty (and delay) in having items shipped from the US (where most of these controllers are made/sold). I wanted to get it working now, not in a week, or more, when a controller would arrive. Additionally, these controllers can run for anywhere from $60-200. I didn’t feel like waiting, and I didn’t feel like paying. So, what’s a resourceful geek supposed to do? Build your own, of course.