Abstract: The disclosed technology includes an on-demand water heater which uses a heat pump to heat the fluid. The on-demand heat pump water heater can have a low fluid capacity heating chamber which has an inlet and an outlet, a heat pump for heating the fluid, and a controller to control the heat pump and maintain the temperature of the fluid at a predetermined temperature. The on-demand heat pump water heater can include one or more temperature sensors, flow sensors, fluid mixing valves, or supplemental heat sources.

Abstract: The disclosed technology includes an on-demand water heater which uses a heat pump to heat the fluid. The on-demand heat pump water heater can have a low fluid capacity heating chamber which has an inlet and an outlet, a heat pump for heating the fluid, and a controller to control the heat pump and maintain the temperature of the fluid at a predetermined temperature. The on-demand heat pump water heater can include one or more temperature sensors, flow sensors, fluid mixing valves, or supplemental heat sources.

Abstract: In an electric water heater having adjustable set point and differential temperatures, upper and lower heating elements, and associated temperature sensors respectively operative to sense upper and lower tank water temperatures, a specially designed control system is provided for controlling the heating elements. The control system is operative to prevent dry firing of the heating elements by measuring temperatures over time with the temperature sensors.

Abstract: The metal tank portion of an electric water heater is protected against corrosion utilizing a corrosion protection system that detects a voltage potential between the sheath portion of a tank water-immersed electric heating element and the tank. In one embodiment of the corrosion protection system the sensed sheath/tank potential is utilized to enable a user of the water heater to accurately gauge the necessity of replacing a sacrificial anode extending into the tank. In another corrosion protection system, the sensed sheath/tank potential is utilized to provide impressed current cathodic protection of the tank and also to prevent dry firing of the electric water heater.

Abstract: A method of controlling water heater pilot flame ignition includes receiving, by a controller of a water heater, a user input and controlling a pilot gas valve to start a gas flow to a pilot burner in response to the user input. The method further includes, in response to the user input, controlling, by the controller, an igniter to generate an ignition spark for lighting a pilot flame. The method also includes controlling, by the controller, the pilot gas valve to maintain the gas flow to the pilot burner if the pilot flame is lit.

Abstract: A water heater has one or more heating elements and an internal wall that causes an increased rate of heating within a sub-volume within the water heater tank. Water from the sub-volume is directed to the tank outlet.

Abstract: A water heater includes a leak detection system. The leak detection system includes a leak sensor assembly that is disposed in a bottom pan of the water heater. The leak sensor assembly includes a sensor housing that has a sensor channel that is formed therein such that the sensor channel is disposed at an elevation from a base of the bottom pan when the sensor housing is disposed on the base of the bottom pan. Further, the leak sensor assembly includes a leak sensor that is disposed in the sensor channel of the sensor housing. The leak sensor detects water that leaks from the water heater and accumulates in the bottom pan when a level of the water in the bottom pan rises to the elevation of the sensor channel and the leak sensor that is disposed therein.

Abstract: A water heater has one or more heating elements and an internal wall that causes an increased rate of heating within a sub-volume within the water heater tank. Water from the sub-volume is directed to the tank outlet.

Abstract: A water heater includes a leak detection system. The leak detection system includes a leak sensor assembly that is disposed in a bottom pan of the water heater. The leak sensor assembly includes a sensor housing that has a sensor channel that is formed therein such that the sensor channel is disposed at an elevation from a base of the bottom pan when the sensor housing is disposed on the base of the bottom pan. Further, the leak sensor assembly includes a leak sensor that is disposed in the sensor channel of the sensor housing. The leak sensor detects water that leaks from the water heater and accumulates in the bottom pan when a level of the water in the bottom pan rises to the elevation of the sensor channel and the leak sensor that is disposed therein.

Abstract: The disclosed technology includes an on-demand water heater which uses a heat pump to heat the fluid. The on-demand heat pump water heater can have a low fluid capacity heating chamber which has an inlet and an outlet, a heat pump for heating the fluid, and a controller to control the heat pump and maintain the temperature of the fluid at a predetermined temperature. The on-demand heat pump water heater can include one or more temperature sensors, flow sensors, fluid mixing valves, or supplemental heat sources.

Abstract: A combustion tube assembly of a water heater includes a combustion tube having an open end, a closed end, and an outflow opening between the open end and the closed end. A cavity of the combustion tube provides a chamber for a combustion of a water heater fuel, where the outflow opening provides an outlet for an exhaust gas resulting from the combustion of the water heater fuel to exit the combustion tube. The combustion tube assembly further includes a spring positioned in the cavity of the combustion tube at the closed end of the combustion tube.

Abstract: A combustion tube assembly of a water heater includes a combustion tube having an open end, a closed end, and an outflow opening located between the open end and the closed end. A cavity of the combustion tube provides a chamber for a combustion of a water heater fuel that produces an exhaust gas that flows down toward the closed end. The combustion tube assembly further includes a diverter structure positioned inside the combustion tube to divert the exhaust gas such that the exhaust gas flows toward the closed end on a first side of the diverter structure and flows from the first side of the diverter structure to the second side of the diverter structure through a flow opening proximal to the closed end. The outflow opening provides an outlet for the exhaust gas that flows to the second side of the diverter structure to exit the combustion tube.

Abstract: The metal tank portion of an electric water heater is protected against corrosion utilizing a corrosion protection system that detects a voltage potential between the sheath portion of a tank water-immersed electric heating element and the tank. In one embodiment of the corrosion protection system the sensed sheath/tank potential is utilized to enable a user of the water heater to accurately gauge the necessity of replacing a sacrificial anode extending into the tank. In another corrosion protection system, the sensed sheath/tank potential is utilized to provide impressed current cathodic protection of the tank and also to prevent dry firing of the electric water heater.

Abstract: A heat pump water heater has a tank, a burner in communication with a fuel source, a flue, and a heat pump system. The heat pump system has a refrigerant path, at least a portion of which forms an evaporator in thermal communication with the flue. Another portion of the refrigerant path is in thermal communication with the water tank volume so that heat transfers from the refrigerant to the water tank volume.

Abstract: A method of controlling water heater pilot flame ignition includes receiving, by a controller of a water heater, a user input and controlling a pilot gas valve to start a gas flow to a pilot burner in response to the user input. The method further includes, in response to the user input, controlling, by the controller, an igniter to generate an ignition spark for lighting a pilot flame. The method also includes controlling, by the controller, the pilot gas valve to maintain the gas flow to the pilot burner if the pilot flame is lit.

Abstract: A water heater has a water supply line, a heat exchanger in fluid communication with the water supply line, a heating element positioned proximate to the heat exchanger, such that when activated, the heating element conveys heat to the heat exchanger and thereby heating water supplied by the water supply line, an output line in fluid communication with the heat exchanger and configured to receive heated water therefrom, a flow sensor configured to cause the heating element to activate in response to sensing a predetermined water flow rate through the water heater, and a bypass flow line operably connected between the water supply line and the output line.

Abstract: A water heater includes a tank defining an interior volume having an inlet and an outlet, a heating element configured to heat water within the tank, and a bypass in fluid communication between the inlet and outlet and configured to divert at least a portion of the supply water from the inlet to the outlet.

Abstract: The metal tank portion of an electric water heater is protected against corrosion utilizing a corrosion protection system that detects a voltage potential between the sheath portion of a tank water-immersed electric heating element and the tank. In one embodiment of the corrosion protection system the sensed sheath/tank potential is utilized to enable a user of the water heater to accurately gauge the necessity of replacing a sacrificial anode extending into the tank. In another corrosion protection system, the sensed sheath/tank potential is utilized to provide impressed current cathodic protection of the tank and also to prevent dry firing of the electric water heater.

Abstract: A water heater includes a leak detection system that is integrated with the water heater. The leak detection system includes a channel that extends circumferentially around the water heater. In one example, the channel is built into the water heater. In another example, the channel is formed by a sensor bracket that is coupled to the water heater. Further, the leak detection system includes a sensor assembly that is configured to detect water that leaks from the water heater. The sensor assembly includes a leak sensor and/or a wicking tube. The wicking tube is disposed around at least a portion of the leak sensor. Further, the wicking tube is disposed in the continuous channel and extends circumferentially along the water heater to create a circumferential area of leak detection around the water heater.

Abstract: A combustion tube assembly of a water heater includes a combustion tube having an open end, a closed end, and an outflow opening between the open end and the closed end. A cavity of the combustion tube provides a chamber for a combustion of a water heater fuel, where the outflow opening provides an outlet for an exhaust gas resulting from the combustion of the water heater fuel to exit the combustion tube. The combustion tube assembly further includes a spring positioned in the cavity of the combustion tube at the closed end of the combustion tube.