will be setting up a similar watering system for my hens this winter here in NW corner of lower Michigan. It's below freezing most of the winter (Nov - March)here, and occasionally below zero. Will be using a double-wall reservoir with heat element wrapped between walls, plus a lamp shining on nipples from below. Trying to decide if reflective material across from the lamp will be worthwhile (reflect lamp heat)in creating even more warmth around nipples. Very interested in suggestions and shared experiences to guide me. I'm new at this!

Andrea --- Since writing this post, we've done a lot more experiments with heated chicken waterers. You can see our favorite version here, which is a bit like the one you describe and worked down into the teens last winter. I hope that helps!