I bought a 100 watt ceramic heat bulb used in reptile cages to do this, but after a quick test it seems that this takes a long time to heat up and cool down. Iâ€™m thinking this will cause an erratic temperature cycle. Will this work or should I just use a standard reflector bulb? Thoughts please.
It's been my experience that you typically only need either heat or cooling at any one time. When the fermentation is active, you still may need cooling even when the ambient temperatures are low. OTOH, you may have to add heat as the fermentation wanes when the temps are relatively mild. You would have to set your trip points wide enough so that the heater isn't triggering the cooling to come on. If you go to a standard bulb (less watts) it will extend the heating times, but the swings should be gradual.
I've had good luck using a 50 watt bulb on all the time when the temps are 20-40 and the controller operating the fridge. My fridge is in an insulated but unheated building.