NOVELTY - The method involves immersing combustion reaction of hydrogen and oxygen, within a flow of water in a combustion vessel (102), for producing water product. The combustion reaction is maintained by combustion unit (110) within the combustion vessel. The water product is diffused to supplement the flow of water. The heat generated by the combustion reaction is provided to increase the temperature of the flow of water to produce the heated water. The average mass of combustion product in supplemented flow of water is between about 15-25% of average mass of supplemented flow of water.    USE - Method of producing heated water used in large-scale electricity generating station for electric power generation. Can also be used in heating systems, steam turbines powering electrical current generators used in building, heat and electricity cogeneration systems, and engine locomotive vehicle such as steam ship and tractor.    ADVANTAGE - The combustion vessel is aligned vertically with respect to gravity, with rounded base that is anchored vertically and braced against horizontal support platform to prevent the vertical downward thrust produced during normal operation from causing the unit to tilt away from vertical alignment, and to prevent transverse vibrational action from rattling the device and skewing the direction of the thrust and resultant steam output. The heating system allows for the power output to be easily scaled up to desired power output simply by swapping in or out one or more heating modules while maintaining operational efficiency. The oxygen generated during off-peak hours using electricity sourced from inexpensive hydro-electric generating stations, or off-peak wind generation projects is stored in bulk during periods of low demand, and used by the power generation system to generate electricity during periods of high demand. The heat and electricity are generated without contributing to pollution and climate change effectively.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a water heating device; and    (2) a water heating system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the water heating device.    Water heating device (100)    Combustion vessel (102)    Water supply (104)    Water conduit (108)    Combustion unit (110)