An appliance to heat a liquid, the appliance including: a vessel to receive the liquid to be heated, the vessel having a generally central upright longitudinal axis, a bottom wall, and a side wall extending upwardly from the bottom wall, with the bottom wall and side wall at least partly enclosing a chamber within which the liquid is heated, with the chamber having an upper region axially spaced from the bottom wall, and a lower region located between the bottom wall and the upper region; a heating element located within the chamber for relative movement therewithin, with the element at least partly formed of ferromagnetic material; a heater base to be positioned relative to the bottom wall of the vessel, the heater base including at least a portion of an induction coil; and connections to deliver an alternating current to the induction coil so as to deliver a magnetic field to the lower region; wherein the element is movable relative to the coil between an operative position at which the element is located within the lower region so as to be energised by the magnetic field to cause heating of the element so that heat generated by the element can be delivered to the liquid via conduction, and an inoperative position at which the element is located in the upper region so as to no longer place an operative load on the induction coil, wherein the element is in the form of a plate centrally located on the axis, characterized in that the plate includes a plurality of bimetallic members (59, 61, 63) located on an underside of the plate, with each of the members possessing at least two positions of stability, and each of the positions responsive to a threshold temperature, and wherein each of the members is actuated at different temperatures. a vessel to receive the liquid to be heated, the vessel having a generally central upright longitudinal axis, a bottom wall, and a side wall extending upwardly from the bottom wall, with the bottom wall and side wall at least partly enclosing a chamber within which the liquid is heated, with the chamber having an upper region axially spaced from the bottom wall, and a lower region located between the bottom wall and the upper region; a heating element located within the chamber for relative movement therewithin, with the element at least partly formed of ferromagnetic material; a heater base to be positioned relative to the bottom wall of the vessel, the heater base including at least a portion of an induction coil; and connections to deliver an alternating current to the induction coil so as to deliver a magnetic field to the lower region; wherein the element is movable relative to the coil between an operative position at which the element is located within the lower region so as to be energised by the magnetic field to cause heating of the element so that heat generated by the element can be delivered to the liquid via conduction, and an inoperative position at which the element is located in the upper region so as to no longer place an operative load on the induction coil, wherein the element is in the form of a plate centrally located on the axis, characterized in that the plate includes a plurality of bimetallic members (59, 61, 63) located on an underside of the plate, with each of the members possessing at least two positions of stability, and each of the positions responsive to a threshold temperature, and wherein each of the members is actuated at different temperatures.