Abstract: Apparatus is described for controlling an electric heater incorporating at least one electric heating element (2A, 2B, 2C) and energized from a single voltage alternating current supply (8). The apparatus includes a control knob (15) for manually selecting any one of a predetermined number of power settings for the heater from the voltage supply (8), the power settings varying progressively between a minimum power setting and a maximum power setting. The apparatus further includes a controller (10) adapted and arranged to supply to the electric heater within a predetermined constant time interval in each power setting a first dissipated power level and a second dissipated power level. The first dissipated power level comprises a first selected proportion of half cycles in a predetermined number of half cycles of the voltage supply and the second dissipated power level comprises a second selected proportion of half cycles in a predetermined number of half cycles of the voltage supply.

Abstract: An electric heating method is described for use with a glass-ceramic top cooking appliance. A first sensor coil is provided in a heater associated with a first heating element and a second sensor coil is provided associated with a second heating element, the first and second sensor coils being adapted to provide first and second electrical output signals respectively. Changes in the first and second electrical output signals are monitored resulting from placement and removal of a metallic cooking utensil on and from the cook top and the ratio of change in the first electrical output signal to change in the second electrical output signal is determined. The first heating element is energised alone in accordance with a first predetermined value, or a first predetermined range of values, of the ratio, resulting from placement of a cooking utensil on substantially only an area of the cook top above the first heating element.

Abstract: A radiant electric heater arrangement is provided for connection to a dual voltage supply which provides a first alternating current supply voltage and a second alternating current supply voltage higher than the first. The arrangement includes a heater having at least one heating element and a manually operable multiple discrete position switch means for manually selecting in sequence a predetermined number of discrete different power settings for the at least one heating element from the voltage supply.

Abstract: A method is described of processing an electrical signal output from a sensor coil located in an electric heater for use under a cook top in a cooking appliance. The sensor coil is employed to operate a switch to switch on and off a heating element in the heater in accordance with placement and removal of a cooking utensil on and from the cook top. The sensor coil is arranged in the heater within magnetic influence of the electrical heating element, the heating element comprising a material which is ferromagnetic below and substantially non-ferromagnetic above a predetermined temperature within an operating temperature range of the heater. The occurrence of an increase in output signal level from the sensor coil is detected and closure of the switch is effected. Subsequently, the occurrence of a decrease in output signal level from the sensor coil is detected and opening of the switch is effected.