Removal of scale and sludge in a steam generator of a fabric treatment appliance

A method of operating a fabric treatment appliance comprising at least one of a tub or drum defining a fabric treatment chamber and a steam generator having a chamber defining an internal volume, the method comprising:

• a steam generation step comprising:
• introducing liquid into the chamber of the steam generator;
• heating the liquid in the chamber to create steam;
• introducing the steam into the fabric treatment chamber;
• and
• after the steam generation step, a steam generator cleaning step comprising:
• heating the chamber, without the introduction of liquid, to a predetermined temperature greater than a liquid to steam phase transformation temperature to evaporate any liquid in the chamber;
• turning off the heater;
• cooling the heating chamber by introducing cold liquid at a temperature less than the predetermined temperature into the chamber whereby cooling of the heated chamber thermally shocks scale formed in the chamber to thereby cause the scale to delaminate from an inside surface of the chamber to form loose scale in the chamber;
• and
• flushing the chamber with cold liquid to rinse the loose scale out of the chamber.