MyQul
Chairman of the Bored
It looks like the temp thing is wired to a pump. Which circulates water through the coils fitted to the lid. So if you get a small batch of water set at the desired temp. The pump activates to circulate the water through the coil until desired temp is achieved. Looking on line it's suggested a fish tank heater in a bucket of water so temp is content and then the pump circulates it as and when.
Mrs MQ definatley wouldn't allow anything like that - you should have seen the look on her face when I put my huge fermentation bag in the my brewing corner to try it for size, "It's not staying there permanantly is it?" she asked. "No love." :whistle:
@ManseMasher that always assuming your Homebrew McGuiver . I certainly couldn't make something like that