I've had a Haier BC112G 30 bottle wine fridge in my basement, largely unused for a couple of years now as the wine has moved into a larger cabinet. I started using it as a fermentation chamber a few brews ago since it can accomodate any of my fermentation vessels (6 & 5 gallon better bottles, 5 gallon glass carboy, and 6 gallon bucket.)
Until today, I've just been using the internal thermostat (cooling only) to maintain a temperature within about 3ºF of the target. This is great for many of the beers I brew, but since my basement is only ~60-65ºF this time of year, I couldn't hold a higher temperature. What's more, as this is a wine cooler, the lowest setpoint I could achieve with the built in thermometer was 45ºF (again +/- 3ºF), so it wasn't well suited for cold crashing, laggering, etc.
As you will see in the photos below, I made a few modifications today to bypass the internal thermostat (as well as the built in control panel), and installed a heating element in the form of a brew belt in the bottom of the chamber. Both the heating element and the fridge compressor are now controlled by a Love controller that I built into a project box.
Finished Product with 5 gallon better bottle as an example. A 6 gallon bottle fits as well, by placing it on the lower 'shelf' and wrapping the brew belt around the wood:
Probe (through drain) and brew belt (through new hole):
Removed the control circuit and hot wired the compressor (see little red jumper cable), ensuring that whenever the unit has power, the compressor is running.
Back pannel view. See the compressor jumper on the left, temp probe inserted in the drain hole in the middle, and the brew belt (not yet wired in) inserted through the new hole on the right:
After these photos were taken I finished securing and sealing all the wiring connections with wire nuts, electrical tape, etc where needed. I also used silicone caulk on the hole that I drilled for the brew belt cord, to protect the insulation from condensation.
You can definitely get more bang for your buck with an old full sized fridge or the like as a fermentation chamber, but if you happen to have one of these Haier units laying around like I did, or see one on Craigslist for a few bucks, this may be useful for you. It fits many types of fermentors, and is relatively compact for those of you with small places.
I've got it running at 70ºF right now in order to help the silicone caulking set. It's been holding a perfect temperature for several hours now. If I warm the chamber up artificially, it cools down via the compressor to the target setpoint very quickly. Warming it up with the brewbelt takes a little longer, but I found it was able to gain 10ºF in air temp inside the chamber in just over 10 minutes.
I'll be running it 'dry' (without beer) for a few more days, just to ensure that I didn't mess anything up, but so far it is working great.All things considered, I'm very happy with how it turned out. I took care while working on this project to ensure that every step is easily reversible, so that if I need extra wine storage capacity in the future (and have another, fermentation option) I can just plug the controller board back in and I'm all set.