I intend to use a heat bulb in my small coop for 3 hens, just enough to keep the water from freezing this winter. My question is, how high should I hang the reflector and bulb in the coop. It only stands 6ft tall and about 4 ft wide every direction. I have ventilation at the roof. its pretty insulated and I don't want the girls to bake. I'm gone long hours and don't want the water to freeze.

hope the pic helps...
hope the pic helps...