Patent ID: 7997295

Claim:
A supplementing water supply controller, the controller including: a housing defining a first flow passage having an inlet connectable to a main water supply, a second flow passage having an inlet connectable to a supplementing water supply at a pressure less than the pressure of the main water supply, and a common outlet for said first and second flow passages which is connectable to a water supply conduit, the housing further defining a chamber which has an opening to the first flow passage and an opening to the second flow passage; and an actuator mounted for movement in the chamber by two diaphragms, wherein one diaphragm is associated with a first end of the actuator and the second diaphragm is associated with the second opposite end of the actuator, wherein in use the first end of the actuator with its associated diaphragm is exposed via the opening to the first flow passage to pressure prevailing at the inlet to the first flow passage, and the second opposite end of the actuator with its associated diaphragm is exposed via the opening to the second flow passage to pressure prevailing at the inlet to the second flow passage, wherein the actuator at its first end with its associated diaphragm is adapted to prevent flow along the first flow passage by sealing against a valve seat defined by the housing, and wherein a surface area of the actuator and its associated diaphragm at the second opposite end exceeds a surface area of the actuator and its associated diaphragm at the first end such that the actuator is moved for a seal to be provided against the valve seat when the ratio of said surface areas at the first and second opposite ends of the actuator is less than the ratio of pressures prevailing at the inlets of the second and first flow passages.