Abstract: A thermally operated mixing valve including a single control knob, a valve member, a thermally responsive control member, and means for positively shutting off the flow of mixed liquid from a mixing chamber when the valve is closed.The valve member is a "jumper" element movable in opposite directions in the control chamber to restrict or cut off the flow of hot or cold liquid respectively. The valve member can abut against a spring loaded annular abutment ring to shut off the flow of hot liquid to the mixing chamber and when the abutment ring reaches the limit of its travel the valve member can move away from it to allow hot liquid to flow to the mixing chamber around the outside of said valve member.