Abstract: A system to protect piping and containers from damage by freezing of contained aqueous liquid includes a temperature-actuated SPDT switch connected at its movable contact to a rechargable battery. The fixed contacts of the switch are connected to two input terminals of a DC motor of a motor-actuated valve having its valve opened or closed depending upon the operation of the switch. The movable contact normally engages the fixed contact that provides voltage to close the valve, if open, as the sensed temperature is above about 35.degree. F., but moves to the other fixed contact when the temperature drops to 35.degree. F. to open automatically the valve. A relay having a coil energized by AC power has a normally open contact coupling the motor and the fixed contact used to close the valve so that closing is inhibited, if the AC power is off, until power is on.