Every time you use hot water, cold water (50f degrees) ground water, runs thru the heat exchanger. The flow switch and PLC activates triggers Solenoid valve B to open, and the water passes thru valve A, C, also opens for returned water. The Pelton wheel around 4 GPM (average Flow), powering the fan. The water coming out of the Pelton wheel, goes in a pressurized well tank and is pumped, back into the system. Through the one-way valve, no water is wasted. The pump, and solenoids valve uses a small amount energy, compared to the total, recovered energy, around 1.5 Tons of Energy. The main power for the Pelton wheel still comes from city water pressure (fan 600 cfm). We still recover several BTUs from the cooling power of the groundwater, or city water through the heat exchanger and the ambient heat in the kitchen 95F degrees to 100 degrees, is used to preheat the hot water, which is around 8.5 degrees increase. The air coming out of the heat exchanger is 18f degrees cooler than the ambient kitchen air.