For the winter I use a 5-gallon bucket with the water nipples. I submerge a cheap (wlamart) aquarium heater that is designed to keep water at 75-ish degrees. That's a bit of overkill for chicken water, but you could use a thermo cube to regulate the temp down.
I know our low temps can't be anywhere close to yours. But we have several weeks of subzero nights and my outdoor bucket has never frozen. Since the aquarium heater sits in the bottom of the bucket, the nipples don't freeze either.
I know our low temps can't be anywhere close to yours. But we have several weeks of subzero nights and my outdoor bucket has never frozen. Since the aquarium heater sits in the bottom of the bucket, the nipples don't freeze either.