Abstract: An apparatus and method for controlling a domestic hot water heater system in which the actual temperature of the water in the storage tank of the system is continuously measured and the measured water temperature is continuously displayed at a location remote from the water heater. There are control means located at a remote location for actuating energizing means at the water heater for heating the water. The energizing means is actuated by the person intending to use the heated water on the basis of the measured temperature of the water displayed at the continuous display at the time of measurement and the intended use of the water.