US Patent 9939172 Thermostatic condensing gas water heater and control method therefor

A thermostatic condensing gas water heater, comprising a burner; a first heat exchanger (7), a second heat exchanger (4), a water inlet pipe (10), and a water outlet pipe (9) provided in succession along the flow direction of the burnt flue gas; a controller; and a water flow channel connecting the first heat exchanger (7) and the second heat exchanger (4) in parallel between the water inlet pipe (10) and the water outlet pipe (9), wherein flow control valves (3, 5) capable of adjusting the water flow distribution of the first heat exchanger (7) and the second heat exchanger (4) are provided on the water flow channel and controlled by the controller.