Abstract: A charging apparatus for an electric storage heater includes a resistance heater in series with a low tariff time switch and a charging switch. While the low tariff time switch is closed, usually at night, an integrator controlled by a differential amplifier controls the charging switch in accordance with the total charge accumulated by the integrator which reflects the use of energy during the preceding day. The charge of the integrator at the end of the day is the result of it being intermittently charged and discharged by a voltage divider circuit which has one or more temperature responsive resistances and transmits a voltage to one input of a differential amplifier for the integrator which can be above or below a reference voltage on the other input of the amplifier.