Abstract: The freezing of water pipes in a dwelling in cold climates is prevented by separating some of the cold water delivered to the dwelling and conducting that separated cold water into heat exchanging relationship with a hot water tank. The thus-warmed water is caused to flow through a cold water main of the dwelling whenever an outlet is automatically periodically opened by means of a temperature sensing valve unit connected to the outlet. The water flowing through the cold water main warms the water in branch lines and at the outlet to prevent that water from freezing.

Abstract: An automatic liquid flow control unit is adapted to be attached to an externally threaded spigot to enable liquid to trickle therethrough in order to avoid liquid freeze-up. The unit includes a rigid conduit which includes an internally threaded fastener which can be directly coupled to the threaded spigot. The conduit carries a solenoid actuated valve and a thermal switch which is electrically coupled to the valve to open the latter to a water trickling mode. The thermal switch senses the outside temperature of the conduit and thus is virtually directly responsive to the temperature of liquid within the conduit. The valve can be opened independently of the thermal switch to provide a normal water flow without removal of the unit from the spigot.