TIME DELAY CIRCUIT FOR HEATING APPLIANCES

摘要

Delayed reheat of off-peak electric heated storage appliances (12) such as water heaters, being aimed at more uniform demand on electrical generation capacity: time delay means (10) creates delay sympathetic to actual depletion of stored thermal energy at commencement of off-peak period and includes thermal energy sensor (14), bridge circuit (16), relaxation oscillator (18), multi-stage binary counter (20) and relay (22) which energises the heating cycle of appliance (12) when the maximum count of counter (20) has been reached. The sensor (14) is arranged to provide an output proportional to the thermal energy content of the reservoir (24). This ouptput controls the oscillator (18) and thereby provides a corresponding time delay during the off-peak period which is such that it permits, in the remainder of the off-peak period, the required thermal energy replenishment of the reservoir (24).