High Side Switching

fungus:

michinyon:
Unless your climate is very bizarre, it seems unlikely that you actually want to try and ferment beer in a fridge.

Maybe he lives in a cold place and has connected the pump backwards.

(Which is also why he needs high-side switching...)

Maybe he's doing the unthinkable and using the well insulated fridge with a small heating element to maintain a nice fermenting temperature with little or no heat loss through the side walls / door etc....