Piglett has an awesome prodedure for hatching box design, a 100 watt heat lamp on a dimmer switch!!

As I have not begun my finishing hatcher constuction yet, I wonder why an huge igloo cooler would need
a thermoelectric switch if the heat were set by a variable heat switch ??? A hatcher such as this would
be placed indoors somewhere as it is basically stink proof .Please confirm or deny my logic here . RR