I have round roost bars in the coop for my hens. I heat the coop with a 250 watt bulb. Should I be worried about frostbite this winter? The light is positioned directly behind the roosting bars. It keeps the coop at about 70' in the coop in 30' weather. It will get down to around 0 this winter. I know from reading on here that I should have used something flat surfaced.