They are concrete pavers, round maybe 16" in diameter. If I put the sticky heater thing between the two pavers. they will heat the pavers and the water sits on the pavers so it's off the ground but not hanging. Then the water shouldn't freeze. I don't like the idea of putting it on the side of the waterer because I clean them at least bi weekly sometimes more. They get pretty nasty and if that thing was stuck to the side it would be harder to do. Plus I have two types of plastic waterers the big one and the small tip it over kind that spills a lot. Am I making sense? I sometimes don't. ADD. Sorry:)
Okay, now I understand. The under tank heater isn't powerful enough to heat the waterer through a paver, I think. My idea was to sit the heater on top of the two pavers, and set the waterer directly on the heater. I can double check if getting wet is a problem, but I don't think a small amount of water would damage it.