Two stage thermostatically controlled electric water heating tank

A two-stage electric hot water heater comprising a cylindrical tank adapted for receiving cold water and dispensing hot water;

• a flue vertically oriented in said tank and surrounded by water in said tank;
• a plurality of vertically-disposed copper tubes deployed in said flue in a substantially tight cluster;
• a plurality of generally U-shaped electric heating elements, each having one leg disposed in a separate one of selected ones of said copper tubes, with the unconnected ends of said heating elements projecting from the bottoms of said selected ones of said copper tubes and the connected top ends of said heating elements bridging said selected ones of said copper tubes, respectively;
• a two-stage thermostat connected in series to selected ones of said heating elements in a first electrical configuration and to all of said heating elements in a second electrical configuration;
• and a single-stage thermostat connected to all of said heating elements, whereby electric current is caused to flow through selected ones of said heating elements at a first selected energy level in said first electrical configuration to rapidly heat the water in said tank to a preselected temperature responsive to operation of said two-stage thermostat and through all of said heating elements at a second selected energy level in said second electrical configuration, responsive to operation of said single-stage thermostat.