I used a smaller one last year and it only went on when the temp went below freezing so since I already have their water on this thermostate I added a seedling heat pad and placed it in the coop with newspaper on top and then hay on top of the newspaper. It does not get hot just warm - I use these mats to start my seeds in the spring so now I get to use in the winter and the spring. Anyone else ever use this heating system? I have a 3 chicken coop so not very big and I keep their slider door open so there is plenty of air flow. Temp will be below 20 tonight so just getting ready and my 2 girls are molting of all times to molt and have very little feathers to keep them warm. This picture was at the beginning of her molting since then she lost much more and the other girl started molting a week after Pearl.