Thermal control apparatus and method

The present invention provides a heating apparatus for heating a load. The heating apparatus comprises a heater having a heating element for receiving electrical power and for converting the electrical power into heat to heat a heating surface of the heater. The heating apparatus also comprises a temperature sensor for sensing and outputting a measurement of the temperature of the heating element, a power actuator for providing the electrical power to the heating element of the heater, a power sensor for sensing and outputting a measurement of the power provided to the heating element by the power actuator, and control circuitry for controlling the power actuator to control the power delivered by the power actuator to the heating element. The control circuitry is configured to receive the temperature measurement from the temperature sensor, receive the power measurement from the power sensor, combine the temperature measurement and the power measurement, and control the power actuator in dependence upon the combined temperature measurement and power measurement. This ensures that the temperature of the heating surface is constant throughout a period when the load is applied.