By David Hope-Ross
I’ve had this fermentation chamber for a few years now and made some improvements over time, and I’m pretty happy with it as it sits now.
I started with a mini fridge I got off of craigslist for 40 bucks. The frame is made from 2×3 and 2×4 lumber I had laying around and measures 37″H x 62″L x 24″W. The height and width are just based off of the of the exterior dimensions of the fridge. I made it plenty deep, and I can fit 4 carboys in there with blowoff pretty easily.
I made the temperature controller myself using an STC-1000, but since then, the Inkbird controllers have come out, so I would just use that if I was going to build one now.
I used both polystyrene and fiberglass foam panel insulation, but I have found that the fiberglass panels behave better when cutting; the polystyrene makes a mess. Make sure you’re using a sharp razor when cutting or the blade will snag on the outer layer of foil. There are 2 layers of one inch foam panel around every surface of the frame. I used press in rope caulk to fill any gaps. It will hold temperatures down to 48 degrees Fahrenheit and I’m thinking about adding another inch of foam so I can go colder and truly lager in it.
The most important mod which makes this whole thing work so well, is that the fridge’s thermostat is bypassed. The thermostat on mini fridges is usually pretty easy to find, just look at whatever is opposing the temperature dial on the inside and the thermostat is usually right there.
If I need to heat the chamber, I just run a space heater off of the heating side of the temp controller. That has worked decently so far, but has a tendency to overshoot.