I don't have a thermostat but the bulb/fan keep the temp stable unless the living room is shut up and starts getting too warm with high 90 degree days. This is only an issue because I don't have central AC and when we go to bed(Which is during the afternoon aka heat of the day) the living room gets warmer from lack of ac. I had to tinker with it a few days before I put eggs in to get the temp right.