Finally setup a fermentation fridge. I started from a used, abused, and ignored LARGE dorm fridge. This is a real fridge with compressor etc. This would have accepted a 5 gallon
carboy with little modification, but I was using my 6.5 gallon carboy, so more modification was required. What I needed to do,
1. remove the shelves
2. remove the door liner (plastic liner that also includes soda shelves) This was held in place by about 20 screws, and also holds in the rubber door gasket
3. had to carve out some of the door insulation
The carboy sits fine in the fridge. Next was temp control. I have a johnson control on order, but was impatient. So I set the fridge to a warmer temperature (turns out to be about 55*F). I would then manually plug and unplug to maintain temp. It holds temp pretty well – there is a lot of thermal inertia in the 5 gallons of wort. Then one night, I forgot to unplug, and by morning my wort was down to about 60*F. So, now I’ve added a timed controller, which will turn on the unit for about 30 minutes in the morning and afternoon. I then run an extra cycle if needed to hold to about 65*F. I’m surprised how well the unit holds temp. I have a arduino based temperature module that tracks temp, average, high and low*. I’ve taped the temp sensor to the side of the carboy, and it reads very close to what the temperature tape shows. It does average a bit with ambient temp – but not too bad.
notes: * yes there is a bug in my code, and the low sometimes gets wonky (showing a very large negative temp here)