Temperature regulators for setting and maintaining pre-set temperatures on electrical heating appliances (cookers, grills, percolators, etc.) consist essentially of a bi-metal strip which, when deflected by the heat from a shunt resistor on the power circuit, operates a switch to make and break the power circuit, the" On" and" Off" periods (and consequently the temperature of the heating elements) being determined by the position of a manual control dial; the " Full " position renders the bi-metal assembly inoperative and thus, particularly in the initial stages of heating, permits continuous operation of the heating element.
thermostatically controlled valves (heading 84.81):
Thermostatic" or " thermostat" steamers, cabinets, etc., in which the temperature is kept constant by means of a thermostat, which are to be classified in their respective headings.