Abstract: A thermostatic mixing valve is described having separate valves for hot and cold water each with a stepping motor to adjust their positions and connected to a microprocessor using a temperature sensor in a mixing chamber to read the mixed temperature and step the motors individually to adjust the valve positions as required.

Abstract: A motorized valve, FIG. 2, is provided with a solenoid operated clutch which is energized when the valve is in operation and which can be de-energized, for example on power failure to allow the valve to be instantaneously driven to a closed position. The valve has a motor with a non-circular shaft driving the screw of a screw and nut mechanism in which the nut carries the valve closure element, and the clutch comprises a plurality of balls carried by a cage and held in engagement with the screw by a clutch ring which is held in the operative position by the solenoid. De-energization of the solenoid allows the ring to be spring-driven allowing the balls to disengage from the groove and allowing the screw to be displaced out of the cage by the driving spring.