Well, I think a fan is needed when dealing with a light bulb, not so much a heating element in a styro foam incubator, but a light bulb gets to hot for the styrofoam. I set a 40 watt light bulb in a mini fridge in my uninsulated unheated shed during the middle of winter, the temps were 18 outside, and the fridge got to 120+ degrees. If you were to use the dimmer I would talk to cmom about the wiring if you are unsure, and she could help you I'm sure. I think the big dimmer switches that connect to the light switch in the wall are the one you want to use. I seen a video on youtube about a woman with a homemade still-air incubator and the temperature was regulated with a dimmer switch that plugs into the wall, and I don't think she hatched any eggs.