I think you have to check those nipples daily. I read some of the negative reviews on the heated nipple waterer and one person discovered that the heater coil had failed, the water had frozen solid, but it took them 3 days to figure it out when they lifted the lid to refill the tank and...
My coop is not heated. Here in northern Minnesota, I often see temps down to -30F to -40F in the dead of winter for a week or two. I have had real good luck with my old-fashioned metal poultry water fount and metal base heater combo. Even when the temps in the coop drop to -30F, my water is...