A thermal control, comprising actuating means operable to act on an on/off actuator of the heating vessel, the on/off actuator having first and second ''on'' states in each of which electrical power may be supplied to a heating element of the vessel for heating liquid provided therein, the arrangement being such that in said first state the actuating means is operable to switch said on/off actuator to an off state at a temperature below the boiling point of said liquid, and in said second state the actuating means is isolated from the on/off actuator so that the on/off actuator itself is operable to switch off the heating element as said liquid boils. A vessel incorporating such a control can be of the cordless type in which case selectably operably controls can be provided on the vessel power base for selecting between sub-boil and boil modes. Furthermore, the invention relates to a wireless liquid heating vessel.