Control system for charging and discharging an electric storage heater

Claim 1

An electric storage heater assembly comprising, a heat storage core, a low tariff period switch and a charging switch in series with said resistance heater, means including an integrator for operating said charging switch, a time clock for operating said low tariff switch, feed circuit means only effective when said tariff switch is open and being responsive to at least one environmental temperature indicative of discharge of heat from said core for charging said integrator, scanning circuit means, controlled by operation of said low tariff switch, for discharging said integrator, switching circuit means responsive to the discharge of said integrator for actuating said charging switch to terminate the charging period, said scanning circuit means including means responsive to at least one other environmental temperature whereby said switching circuit means actuates said charging switch to terminate the charging period at the end of a time period determined by the charge on said integrator and said other environmental temperature, said environmental temperature responsive means of said scanning circuit means including temperature responsive NTC resistor means to vary the length of said time period inversely relative to said other environmental temperature.