Don't worry Lynn, I would not even let my greys get that cold, definitely won't let the reds get anywhere near that. I got the CHE in the mail today but not the thermostat. I put it on anyway and will keep an eye on the temps all night to make sure it doesn't overheat. So far it seems to be working perfectly. I will insulate at least behind the tank. The wall they are next to is plaster and gets quite cold in the winter, so insulating the back of it will keep it from chilling too much I think, very good idea!