Abstract: A metering valve for a water heater system is provided. The metering valve is configured to selectively control the amount of water flowing into the water tank and/or cold-water bypass shunt through rotation of a rotor. The rotor is attached to the motor such that when the motor is driven, the rotor is rotated in either the clockwise or counterclockwise direction. The rotor is shaped such that, depending on the degree of rotation of the rotor, the size of the openings at the cold water inlet and the cold water bypass shunt (as well as the water inlet into the metering valve) are adjusted.