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: An apparatus for heating water has a tank for storing water and an air conditioning system that defines a refrigerant flow path through which refrigerant flows. The refrigerant flow path passes through a heat exchanger so that refrigerant heat is contributed to the tank. The heat exchanger houses a phase change material. A controller controls operation of the water heating apparatus.

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: 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 is provided with monitor/diagnostic display apparatus that selectively provides a user with visual or other type of indicia of the recovery time for the water heater. The apparatus includes a monitoring unit that may be mounted on the water heater, and a display unit that may be mounted either on the water heater or remotely therefrom.

Abstract: A water heater is provided with monitor/diagnostic display apparatus that selectively provides a user with visual or other type of indicia of the remaining hot water availability of, the recovery time for, and the overall efficiency of the water heater. The apparatus includes a monitoring unit that may be mounted on the water heater, and a display unit that may be mounted either on the water heater or remotely therefrom.

Abstract: A water heater is provided with monitor/diagnostic display apparatus that selectively provides a user with visual or other type of indicia of the recovery time for the water heater. The apparatus includes a monitoring unit that may be mounted on the water heater, and a display unit that may be mounted either on the water heater or remotely therefrom.

Abstract: A water heater is provided with monitor/diagnostic display apparatus that selectively provides a user with visual or other type of indicia of the remaining hot water availability of, the recovery time for, and the overall efficiency of the water heater. The apparatus includes a monitoring unit that may be mounted on the water heater, and a display unit that may be mounted either on the water heater or remotely therefrom.

Abstract: A fuel-fired low NOx water heater extending along a vertical axis has a radiant fuel burner disposed in its combustion chamber. The entire burner combustion air quantity is delivered to the burner from outside the combustion chamber via a horizontally serpentined flow path extending through an internal portion of the water heater. This serpentined air inflow path configuration causes a substantial portion of particulate matter in the incoming combustion air to be removed therefrom before entering and potentially clogging the burner.

Abstract: A fuel-fired, power vented water heater has a combustion chamber with an outer wall portion defined by an arrestor plate in which flame quenching air inlet openings are formed. All combustion air entering the combustion chamber must first pass through an air inlet plenum extending outwardly from the arrestor plate and then pass inwardly through the flame quenching openings into the combustion chamber. The air inlet plenum is provided with a normally closed inlet damper which automatically closes during non-firing periods of the water heater to prevent passage of combustion air (and extraneous flammable vapors, if present, adjacent the water heater) into the combustion chamber, and opens during firing periods of the water heater to permit operative combustion air delivery to the combustion chamber.

Abstract: A fuel-fired natural draft water heater is provided with a self-powered, low NOx burner system in which a thermoelectric generator is positioned to be heated by the water heater's fuel burner during firing thereof and used to power an auxiliary combustion air fan which operates to supply to the burner system a quantity of combustion air in addition to that normally supplied by the natural draft of the water heater during operation thereof. The burner system is configured in a manner such that the water heater is operative even if either or both of the thermoelectric generator and the auxiliary combustion air fan fail to function.

Abstract: A power vented, gas fired water heater has a main gas burner disposed within a combustion chamber partially bounded by an arrestor plate having a spaced series of flame quenching combustion air inlet openings therein. To provide for a “soft” ignition of extraneous flammable vapors entering the combustion chamber and to limit the build-up of unignited flammable vapors within the combustion chamber during non-demand periods of the water heater, a non-flame type ignition device is disposed within the combustion chamber and operated at least intermittently during such non-demand periods.

Abstract: Fuel fired power vented and natural draft type water heaters are provided with flammable vapor sensors operative to detect flammable vapors exteriorly adjacent the water heater and responsively preclude fuel flow to the burner portion of the water heater. In each water heater a flow tube is extended between the flammable vapor sensor and the draft structure of the water heater and forms a flow path isolated from the combustion chamber of the water heater. In the event that flammable vapors are present exteriorly adjacent the water heater, the forced or natural draft of the water heater creates a biased flow of flammable vapors which is sequentially drawn across the vapor sensor and through the isolated flow path to the draft structure of the water heater.