Abstract: A water heater includes a tank configured to hold a fluid, a sacrificial anode located within the tank, and a controller coupled to the sacrificial anode. The controller is configured to selectively complete and break an electrical circuit connecting the tank and the sacrificial anode. The controller is also configured to measure a shorted anode current through the electrical circuit, to determine a modulation duty cycle based on a current setpoint and the measured shorted anode current, and to repeatedly complete and break the electrical circuit using the modulation duty cycle.

Abstract: A water heater includes a tank configured to hold a fluid, a sacrificial anode located within the tank, and a controller coupled to the sacrificial anode. The controller is configured to selectively complete and break an electrical circuit connecting the tank and the sacrificial anode. The controller is also configured to measure a shorted anode current through the electrical circuit, to determine a modulation duty cycle based on a current setpoint and the measured shorted anode current, and to repeatedly complete and break the electrical circuit using the modulation duty cycle.

Abstract: A water heater system includes a tank for storing water; a flue assembly positioned within the tank, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank; a burner in fluid communication with an inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly, the exhaust assembly having a threshold temperature above which the exhaust assembly is not suitable; and an exhaust assembly including a fan, wherein at least in the low input mode, the flue gases condense in the flue assembly, and wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below the threshold temperature at least in the high input mode.

Abstract: A water heater system includes a tank for storing water; a flue assembly positioned within the tank, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank; a burner in fluid communication with an inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly, the exhaust assembly having a threshold temperature above which the exhaust assembly is not suitable; and an exhaust assembly including a fan, wherein at least in the low input mode, the flue gases condense in the flue assembly, and wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below the threshold temperature at least in the high input mode.

Abstract: A sacrificial anode assembly. The sacrificial anode assembly includes a sacrificial anode, an insulator positioned around an end of the anode, an electric coupler positioned around the insulator and extending beyond the end of the anode, the electric coupler electrically isolated from the anode, a resistor having a first lead and a second lead, the first lead electrically connected to the anode and the second lead electrically connected to the electric coupler, and a cap positioned around the electric coupler, the cap electrically connected to the electric coupler and electrically isolated from the anode. The cap complete encapsulates the resistor, the first lead, and the second lead.

Abstract: A sacrificial anode assembly. The sacrificial anode assembly includes a sacrificial anode, an insulator positioned around an end of the anode, an electric coupler positioned around the insulator and extending beyond the end of the anode, the electric coupler electrically isolated from the anode, a resistor having a first lead and a second lead, the first lead electrically connected to the anode and the second lead electrically connected to the electric coupler, and a cap positioned around the electric coupler, the cap electrically connected to the electric coupler and electrically isolated from the anode. The cap complete encapsulates the resistor, the first lead, and the second lead.

Abstract: A fluid-heating apparatus for heating a fluid and method of operating the same. The fluid-heating apparatus includes a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source. The control circuit is configured to determine whether a potential dry-fire condition exists for the heating element. In one implementation, the method includes applying a first electric signal to the heating element, detecting a first value of an electrical characteristic during the application of the first electric signal, applying a second electric signal to the heating element, applying a third electric signal to the heating element, detecting a second value of the electrical characteristic during the application of the third electric signal; and determining whether a potential dry-fire condition exists based on the first and second values.

Abstract: A water heater includes a sealed combustion chamber and one or more fans for raising pressure in the combustion chamber to increase efficiency of the water heater. The pressure permits a more restrictive baffle to be used in the flue compared to baffles used in atmospheric water heaters. The water heater may include a water temperature sensor that activates the fan without activating the burner if water temperature raises above a desired temperature. The water heater may also include pressure and vapor sensors to ensure the combustion chamber is properly sealed and there are no flammable vapors present prior to igniting the burner. The fans are relatively small and run off the same DC power that runs an electric gas valve. The fans may be, for example, 12 or 24 Volt fans with power inputs of about 10 Watts or less.

Abstract: A sacrificial anode assembly. The sacrificial anode assembly includes a sacrificial anode, an insulator positioned around an end of the anode, an electric coupler positioned around the insulator and extending beyond the end of the anode, the electric coupler electrically isolated from the anode, a resistor having a first lead and a second lead, the first lead electrically connected to the anode and the second lead electrically connected to the electric coupler, and a cap positioned around the electric coupler, the cap electrically connected to the electric coupler and electrically isolated from the anode. The cap complete encapsulates the resistor, the first lead, and the second lead.

Abstract: A water heater includes a sealed combustion chamber and one or more fans for raising pressure in the combustion chamber to increase efficiency of the water heater. The pressure permits a more restrictive baffle to be used in the flue compared to baffles used in atmospheric water heaters. The water heater may include a water temperature sensor that activates the fan without activating the burner if water temperature raises above a desired temperature. The water heater may also include pressure and vapor sensors to ensure the combustion chamber is properly sealed and there are no flammable vapors present prior to igniting the burner. The fans are relatively small and run off the same DC power that runs an electric gas valve. The fans may be, for example, 12 or 24 Volt fans with power inputs of about 10 Watts or less.

Abstract: A water-resistant porcelain enamel coating and method of making the same is provided. The porcelain enamel coating is prepared using a borosilicate glass frit, and mill additions of silica and a zirconia compound. The mixture is applied to a metal substrate and fired, resulting in a water-resistant coating that resists cracking and crazing. The coating is particularly useful in water heaters. In one embodiment, the coating comprises a fine zirconia compound having a median particle size of less than 10 microns.

Abstract: A fluid-heating apparatus for heating a fluid and method of operating the same. The fluid-heating apparatus includes a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source. The control circuit includes a current path from the power source to the heating element back to the power source, a switch connected in the current path, and a current sensor. The method includes initiating a heating state of the fluid-heating apparatus, initiating a non-heating state of the fluid-heating apparatus, applying a voltage to the heating element during the non-heating state, sensing a leakage current of the heating element during the application of the voltage, and determining a degradation of the heating element with the sensed leakage current.

Abstract: A fluid-heating apparatus for heating a fluid and method of operating the same. The fluid-heating apparatus includes a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source. The control circuit is configured to determine whether a potential dry-fire condition exists for the heating element. The method includes applying a first electric signal to the heating element, detecting a first value of an electrical characteristic during the application of the first electric signal, applying a second electric signal to the heating element, applying a third electric signal to the heating element, detecting a second value of the electrical characteristic during the application of the third electric signal; and determining whether a potential dry-fire condition exists based on the first and second values.

Abstract: A water heater includes a sealed combustion chamber and one or more fans for raising pressure in the combustion chamber to increase efficiency of the water heater. The pressure permits a more restrictive baffle to be used in the flue compared to baffles used in atmospheric water heaters. The water heater may include a water temperature sensor that activates the fan without activating the burner if water temperature raises above a desired temperature. The water heater may also include pressure and vapor sensors to ensure the combustion chamber is properly sealed and there are no flammable vapors present prior to igniting the burner. The fans are relatively small and run off the same DC power that runs an electric gas valve. The fans may be, for example, 12 or 24 Volt fans with power inputs of about 10 Watts or less.

Abstract: A water-resistant porcelain enamel coating and method of making the same is provided. The porcelain enamel coating is prepared using a borosilicate glass frit, and mill additions of silica and a zirconia compound. The mixture is applied to a metal substrate and fired, resulting in a water-resistant coating that resists cracking and crazing. The coating is particularly useful in water heaters. In one embodiment, the coating comprises a fine zirconia compound having a median particle size of less than 10 microns.

Abstract: A water-resistant porcelain enamel coating and method of making the same is provided. The porcelain enamel coating is prepared using a borosilicate glass frit, and mill additions of silica and a zirconia compound. The mixture is applied to a metal substrate and fired, resulting in a water-resistant coating that resists cracking and crazing. The coating is particularly useful in water heaters. In one embodiment, the coating comprises a fine zirconia compound having a median particle size of less than 10 microns.

Abstract: A water heater includes a storage tank communicating with a cold water supply pipe and a hot water supply pipe for the respective supply of cold water to, and removal of hot water from, the tank. The water heater also includes an insulated heat recovery module communicating between the cold water supply pipe and the tank. The heat recovery module defines a cavity, and the cold water supply pipe communicates with a lower portion of the cavity. The heat recovery module has a smaller surface area-to-volume ratio than the cold water supply pipe. When water in the tank is heated, some water is thermally displaced from the tank and into the cavity. Consequently, water is displaced out of the lower portion of the cavity and into the cold water supply pipe. Therefore, only the coldest water is displaced out of the cavity, and thermal energy loss is reduced.

Abstract: A self-cleaning water heater element is provided. The water heater element is plated with a layer of gold such that the gold surface has a low surface roughness. The smooth gold surface inhibits scale formation on the water heater element. The gold-plated smooth-surfaced water heater element may be manufactured by coating a standard water heater element with an adhesion layer, electroplating a layer of bright nickel on the adhesion layer, and electroplating a gold layer on top of the bright nickel layer.

Abstract: A scale-inhibiting water heater element is provided. The water heater element is coated with a diamond-like coating which has low surface tension to keep scale from forming, and is thermally conductive, which helps prevent overheating. The scale-inhibiting water heater element may be manufactured, for example, by coating a standard water heater element with an amorphous silicon adhesion layer, and then applying a diamond-like coating using a pulsed-glow discharge process.

Abstract: A combined potable water heater and hydronic heating system including: a water tank for holding hydronic heating water; a flue extending through the tank; a burner below the flue so that heat and exhaust gases generated by the burner pass through the flue to heat the water in the tank; and a potable water container mounted in the tank so that the hydronic heating water heats the water in the potable water container and so that the hydronic water is separated from the potable water.