Patent ID: 7770807

Claim:
A controller for a water mixing valve having a water outlet with an outlet water temperature sensor and having separately operable hot and cold water inlet valves, the controller including: an input for receiving a signal from the outlet water temperature sensor; and respective outputs for operating the hot and cold water inlet valves, the controller being arranged: to control the hot and cold water inlet valves to respective states which provide water in the water outlet having a temperature, as sensed by the outlet water outlet temperature sensor, selected by a user; upon detection by the outlet water temperature sensor of an outlet temperature less than that selected by the user to control the hot and cold water valve inlets to provide progressively a higher proportion of hot water in the water outlet; to judge whether or not the hot water inlet valve has been in a state to provide maximum flow of hot water in the water outlet for a predetermined period; and if the hot water inlet valve has been in the state to provide maximum flow of hot water inlet in the water outlet for the predetermined period whilst the outlet temperature remains less than that selected by the user, to move the hot and cold water inlet valves to states to provide a mixture of hot and cold water in the water outlet.