Abstract: A solar heater control system is disclosed for use with a water reservoir and a solar collector. Forced circulation of water in the solar heater system is provided by a pump, and valve means provides direct control of water flow in various parts of the solar heater system. Both the pump and the valve means are collected by control means which accepts inputs in the form of temperatures sensed in the water reservoir and in the solar collector. The control means controls the pump and the valve means to cause circulation of water within the system when sensed conditions are suitable for heating, and automatic drainage of the solar collector is effected whenever freezing or over temperature conditions are sensed, or when a power failure occurs. When neither heating conditions nor drainage conditions are sensed, fluid communication between the solar collector and the remainder of the system is terminated by the valve means to isolate the water in the solar collector from the water in the remainder of the system.