Circulating pump with thermostat
I have a 1550 gallon water holding tank and plumbing in an outshed in Fairbanks, Alaska. The pump and pressure tank are also in the outshed heated with an electric heater. To save energy I'm thinking to install a circulating pump inside the tank that circulates through the plumbing inside the outshed to keep it from freezing but not necessarily to the portion of water pipe going under ground to the crawlspace of the house. It should also have a thermostat to start heating when the temp of the water gets to 32 degrees or so. Is there any such thing and if so, how would it be installed? Thanks!