The primary purpose of the fridge is to maintain the perfect brew temperature during fermentation. For ales this is around the 18C mark. Sure, fridges come with their own temperature control but you’re never going to see anything about ~6C. So you need some sort of additional control mechanism to achieve the temperature ranges we want to play with.
The solution is a thermostat that sits between the fridge and the power socket that turns the fridge on and off in response to a temperature probe that sits inside the fridge. You can buy such controllers from homebrew shops – but you can also easily assemble your own for a fraction of the price.
The device that I found on ebay is advertised as an aquarium controller. I don’t think it actually is – it’s just a generic industrial controller – the STC-1000, for what it’s worth.
This device is has two switching circuits, one for cooling and one for heating, meaning that you can use it in conjunction with a heating pad for a wide variety of tasks and all throughout the year.
The connections on the back are simply screw-down terminals so you’ll need an extension cord (or two if you want both heating and cooling circuits), some terminal strip, cable ties and an appropriate electrically safe container to mount it in.
Spend for my thermostat: $40
Retail thermostat: $120
Spend so far: $195
Savings so far: $1660