Abstract: An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

Abstract: An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

Abstract: An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

Abstract: An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

Abstract: A water heating system including a tank, a first heating element, a second heating element, a first temperature sensor, a second temperature sensor, a controller having an electronic processor and a memory. The controller is configured to determine an output temperature setpoint, determine whether a period of expected high water demand is approaching, and in response to determining that the period of expected high water demand is approaching, activate the second heating element. The controller is further configured to deactivate the second heating element when a second temperature sensed by the second temperature sensor crosses a second temperature threshold, activate the first heating element when the second temperature crosses the second temperature threshold, and deactivate the first heating element. Wherein the first temperature threshold is lower than the second temperature threshold and the first and second temperature thresholds are higher than the output temperature setpoint.

Abstract: A storage-type water heater including a tank configured to contain a fluid, a powered anode at least partially disposed in the fluid, and an electronic processor. The electronic processor is configured to receive a current measurement of the powered anode, determine whether the current measurement exceeds a maximum threshold, record, when the current measurement exceeds the maximum threshold, a plurality of tank potential measurements over a duration of time, determine, based on the recorded tank potential measurements, a predicted time to tank failure, and output an alert corresponding to the predicted time to tank failure.

Abstract: A gas-fired appliance includes a tank configured to store a fluid to be heated, a powered anode extending into the tank and configured to generate an electric anode current, and a combustion chamber including a burner configured to generate products of combustion. The appliance also includes an exhaust structure, a heat exchanger, and an electronic processor coupled to the powered anode. The products of combustion flow from the combustion chamber to the exhaust structure via the heat exchanger. The electronic processor is configured to determine a duty cycle of the burner, determine whether the duty cycle of the burner exceeds a predetermined threshold, increase a magnitude of a protection parameter of the powered anode from a first value to a second value when the duty cycle of the burner exceeds the predetermined threshold, and control the powered anode according to the second value of the protection parameter.

Abstract: A method of determining an abnormal condition in a water heater. The method including sensing, via a temperature sensor, a plurality of temperatures and filtering, using a first time constant, the plurality of temperatures to produce a first plurality of filtered temperatures. The method further including determining, via a controller, if at least one temperature of the first plurality of filtered temperatures crosses a first temperature threshold, and when at least one temperature of the first plurality of filtered temperatures crosses a second temperature threshold, filtering, using a second time constant, the plurality of temperatures to produce a second plurality of filtered temperatures. The method further including initiating, via the controller, a shutdown procedure when at least one temperature of the second plurality of filtered temperatures, crosses a third temperature threshold.

Abstract: A water heating system including a tank, a first heating element, a second heating element, a first temperature sensor, a second temperature sensor, a controller having an electronic processor and a memory. The controller is configured to determine an output temperature setpoint, determine whether a period of expected high water demand is approaching, and in response to determining that the period of expected high water demand is approaching, activate the second heating element. The controller is further configured to deactivate the second heating element when a second temperature sensed by the second temperature sensor crosses a second temperature threshold, activate the first heating element when the second temperature crosses the second temperature threshold, and deactivate the first heating element. Wherein the first temperature threshold is lower than the second temperature threshold and the first and second temperature thresholds are higher than the output temperature setpoint.

Abstract: A water heater including a tank for holding heated water made at least partially of mild steel, a heat exchanger for heating water made at least partially of stainless steel, an inlet to add water to the tank, an outlet to withdraw water from the tank, and an anode connected to the tank. An inner water-facing surface of the tank is coated at least partially with a protective coating, and a water-facing surface of the heat exchanger is coated at least partially with a protective coating.

Abstract: A method of determining an abnormal condition in a water heater. The method including sensing, via a temperature sensor, a plurality of temperatures and filtering, using a first time constant, the plurality of temperatures to produce a first plurality of filtered temperatures. The method further including determining, via a controller, if at least one temperature of the first plurality of filtered temperatures crosses a first temperature threshold, and when at least one temperature of the first plurality of filtered temperatures crosses a second temperature threshold, filtering, using a second time constant, the plurality of temperatures to produce a second plurality of filtered temperatures. The method further including initiating, via the controller, a shutdown procedure when at least one temperature of the second plurality of filtered temperatures, crosses a third temperature threshold.

Abstract: A gas-fired appliance includes a tank configured to store a fluid to be heated, a powered anode extending into the tank and configured to generate an electric anode current, and a combustion chamber including a burner configured to generate products of combustion. The appliance also includes an exhaust structure, a heat exchanger, and an electronic processor coupled to the powered anode. The products of combustion flow from the combustion chamber to the exhaust structure via the heat exchanger. The electronic processor is configured to determine a duty cycle of the burner, determine whether the duty cycle of the burner exceeds a predetermined threshold, increase a magnitude of a protection parameter of the powered anode from a first value to a second value when the duty cycle of the burner exceeds the predetermined threshold, and control the powered anode according to the second value of the protection parameter.

Abstract: Systems and methods are described for controlling the current of a sacrificial anode based on the conductivity state of the water. An unregulated current of the sacrificial anode relative to the water tank is measured and a conductivity state of the water is identified based on the measured unregulated current. A maximum current limit for the sacrificial anode is determined based on the conductivity state of the water and the current of the sacrificial anode is limited such that the current does not exceed the determined maximum current limit.

Abstract: Systems and methods are described for controlling the current of a sacrificial anode based on the conductivity state of the water. An unregulated current of the sacrificial anode relative to the water tank is measured and a conductivity state of the water is identified based on the measured unregulated current. A maximum current limit for the sacrificial anode is determined based on the conductivity state of the water and the current of the sacrificial anode is limited such that the current does not exceed the determined maximum current limit.

Abstract: A dry-fire protection system and method. The dry-fire protection system includes a tank, a heating element, a powered electrode, a sensor, and a microcircuit. The heating element and the powered electrode are positioned in the tank, the powered electrode being positioned above the heating element. The powered electrode includes an electrode wire and a connector having an electrical connector coupled to the electrode wire, but electrically isolated from the tank, and a fastener for coupling the powered electrode to the tank. The sensor detects an electrical characteristic of a circuit formed by the tank, the powered electrode, and water in the tank. The microcircuit determines if a possible dry-fire condition exists based on a signal received from the sensor.

Abstract: Methods and systems for evaluating the condition of a water tank having a powered anode protection system. The water heater includes a storage tank to hold water, a powered anode, and a control circuit. The control circuit includes a variable voltage supply, a voltage sensor, and a current sensor. The control circuit is configured to compare a measured parameter to a threshold. In some constructions, the threshold is indicative of a condition of the storage tank at which the powered anode is no longer able to protect the storage tank from corrosion. In other constructions, the threshold is predicative of a potential failure of the storage tank caused by corrosion. In some constructions, the control circuit is configured to estimate a time remaining until the predicted failure of the storage tank.

Abstract: Methods and systems for evaluating the condition of a water tank having a powered anode protection system. The water heater includes a storage tank to hold water, a powered anode, and a control circuit. The control circuit includes a variable voltage supply, a voltage sensor, and a current sensor. The control circuit is configured to compare a measured parameter to a threshold. In some constructions, the threshold is indicative of a condition of the storage tank at which the powered anode is no longer able to protect the storage tank from corrosion. In other constructions, the threshold is predicative of a potential failure of the storage tank caused by corrosion. In some constructions, the control circuit is configured to estimate a time remaining until the predicted failure of the storage tank.

Abstract: A powered anode assembly. The powered anode assembly includes an electrode wire, a shield tube, and a connector assembly. The electrode wire has a first portion and a second portion. The shield tube substantially covers the first portion of the electrode wire, leaving a small portion of the first portion open. The connector assembly includes a connector that is electrically connected to the electrode wire, and a fastener that is physically coupled to but electrically isolated from the connector.

Abstract: A dry-fire protection system and method. The dry-fire protection system includes a tank, a heating element, a powered electrode, a sensor, and a microcircuit. The heating element and the powered electrode are positioned in the tank, the powered electrode being positioned above the heating element. The powered electrode includes an electrode wire and a connector having an electrical connector coupled to the electrode wire, but electrically isolated from the tank, and a fastener for coupling the powered electrode to the tank. The sensor detects an electrical characteristic of a circuit formed by the tank, the powered electrode, and water in the tank. The microcircuit determines if a possible dry-fire condition exists based on a signal received from the sensor.

Abstract: A water heater having a powered electrode and a method of controlling the water heater. The water heater includes a tank to hold water, a heating element, an electrode, and a control circuit. The control circuit includes a variable voltage supply, a voltage sensor, and a current sensor. The control circuit is configured to controllably apply a voltage to the electrode, determine the potential of the electrode relative to the tank with the voltage sensor when the voltage does not power the electrode, determine a current applied to the tank after the voltage powers the electrode, determine a conductivity state of the water in the tank based on the electrode potential and the current, and define the voltage applied to the powered electrode based on the conductivity state. The control circuit of the water heater can also determine whether the water heater is in a dry-fire state.