When a tap is opened water flows from the supply (26) to an outlet (23) to the tap. A hydraulic motor (10) between these points recovers the kinetic and potential energy in the water, and has a controller with a rod (11) with a small piston (12) at one end and a large piston (13) at the other one. The small piston works in a cylinder (14) connected to the inlet (18) and the large one in a cylinder (15) on the outlet (23). The differential pressure across the motor (20) moves the rod which controls a valve (22) regulating the rate of flow. The outlet cylinder forms a buffer volume to give constant flow at the tap.
展开▼