Just a thought; where I live it freezes at night, at least, and most often for most of the day, for months at a time and I do not heat. In addition to the the metal waterer, I have two durable old fashioned rubber horse bowls. In the morning, you kick em over with your barn boots, and refill em, or most days just crack the ice on top with a stick.
I have a friend who's raised chickens for forty years and she swears by bringing her birds warm water every morning- says it highly us the egg count in winter. I tried it and, though it was far from a scientifically controlled experiment, I got an awful lot of eggs, straight through the coldest months. But I found carrying warm water out to work just as well as getting a warmer, on her advice. I'm going out there anyway, to let everybody out and say good morning! Stops me from beeing a big woos on cold days!
P.S. May I say that kicking the rubber bowls is often the most fun part of my day. My teens like it too.
Love.
