Most of you have seen my Fridge-a-Bator and know it has the wafer thermostat. We use a woodstove for heat, so it's much cooler at night in the room than in the daytime. We find that the temps in the hatcher rise about a few tenths of a degree at night, up to a half degree and couldn't figure out why since they are so, so stable in this hatcher usually. My DH thinks its because the metal lever of the thermostat sits outside the fridge and transfers the cold from the room to the wafer, thereby making it kick on the heat and warm up the bator during the night. If I dont adjust it at all, as the house warms up, the temps in the hatcher slowly regulate back down. They dont rise out of acceptable ranges, but I thought I would mention this little observation we made so it may help someone. The fridge is super-insulated and holds temp and humidity extremely stable, and the only time we ever see it fluctuate is when the house cools way off.