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 method of operating a water heater, the method including determining a predicted variation of a hot water consumption rate variable over a future time period and calculating a total required operating time of the water heater over that time period. The method further includes determining multiple possible operating profiles of the water heater that provide the total required operating time, and calculating a minimum hot water reserve for each profile. One of the profiles is selected based at least partially on that profile providing a minimum hot water reserve that is not less than a predetermined desired reserve capacity and the water heater is operated over the time period using that profile. The selected profile may be the profile that is calculated to have the lowest operational cost.

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 including a tank, first and second heating elements, first and second temperature sensors, a communication module, and a controller. The controller is operable to determine a first temperature value related to a first temperature sensed by the first temperature sensor, determine a second temperature value related to a second temperature sensed by the second temperature sensor, and receive a command from the external controller. When the received command is a first command, the controller control current to the first heating element based on the first temperature value traversing a first set point, and controls current to the second heating element based on the second temperature value traversing a second set point. When the received command is a second command, the controller controls current only to the first heating element and not the second heating element, the control being based on the first temperature value.

Abstract: A flame rod analysis system, methods for determining a condition of a flame and a flame rod, and circuits for determining a condition of a flame and a flame rod. The flame rod analysis system comprises energy storage connectable to a flame rod, a pulsed source connected to the energy storage and providing a voltage pulse or a current pulse, and a buffer to allow a processor to measure a buffered voltage at various time points. Flame rod analysis systems can distinguish between various flame conditions (no flame, low flame, etc.) while simultaneously characterizing the condition of the flame rod (shorted to ground, contaminated, etc.). Some flame rod analysis systems can directly measure the resistance of the flame rod.

Abstract: A water heater venting system, the water heater venting system comprising a main exhaust vent; and a first water heater in communication with a second water heater. The first water heater including an inlet, a blower assembly including a motor, an exhaust vent coupled to the main exhaust vent, a fluid flowpath created by fluid communication between the inlet, the blower assembly, and the exhaust vent, a sensor positioned along the fluid flowpath, and a controller electrically coupled to the sensor and the motor of the blower assembly, the controller controlling the speed of the motor based on at least one of an input from the sensor and an input from the second water heater.

Abstract: System and methods of operating a water heater receiving power from an electrical grid. The water heater includes a heating element, a controller, and a first control circuit. The first control circuit including an energizing terminal and a microprocessor. The method includes connecting an energizing terminal of the first control circuit between a power output terminal of the controller and the heating element, receiving driving power from the controller based on a temperature signal. The method also includes receiving a control signal from the controller based on electrical grid information, and selectively energizing the heating element, by the microprocessor of the first control circuit and through the energizing terminal of the first control circuit based on the control signal.

Abstract: System and method for grid load-up dual set point. The invention provides a method of operating a water heater having a tank configured to store water. The method includes heating, via a first heating element, a first portion of the water to a first temperature set point. The method also includes heating, via a second heating element, a second portion of the water to a second temperature set point, the second temperature set point being greater than the first temperature set point. The method additionally includes receiving a load-up signal from a grid controller, and heating, via the first heating element, the first portion of the water to the second temperature set point upon receiving the load-up signal.

Abstract: System and methods of operating a water heater receiving power from an electrical grid. The water heater includes a heating element, a controller, and a first control circuit. The first control circuit including an energizing terminal and a microprocessor. The method includes connecting an energizing terminal of the first control circuit between a power output terminal of the controller and the heating element, receiving driving power from the controller based on a temperature signal. The method also includes receiving control signals from the controller based on electrical grid information, and selectively energizing the heating element, by the microprocessor of the first control circuit and through the energizing terminal of the first control circuit based on the control signals.

Abstract: A pressure probe assembly for attachment to a venturi of a gas-fired appliance, where the venturi includes a body having an inlet end, an outlet end, and a wall defining a mixing chamber extending from the inlet end to the outlet end about an axis. A support member is detachably coupled to the mixing chamber. A first pressure probe is coupled to the support member and has a first pressure tap disposed substantially adjacent the axis. A second pressure probe is coupled to the support member and has a second pressure tap disposed substantially adjacent the mixing chamber wall. Also disclosed is a gas-fired appliance, such as a water heater, including the pressure probe assembly.

Abstract: A flame rod analysis system, methods for determining a condition of a flame and a flame rod, and circuits for determining a condition of a flame and a flame rod. The flame rod analysis system comprises energy storage connectable to a flame rod, a pulsed source connected to the energy storage and providing a voltage pulse or a current pulse, and a buffer to allow a processor to measure a buffered voltage at various time points. Flame rod analysis systems can distinguish between various flame conditions (no flame, low flame, etc.) while simultaneously characterizing the condition of the flame rod (shorted to ground, contaminated, etc.). Some flame rod analysis systems can directly measure the resistance of the flame rod.

Abstract: System and methods of operating a water heater receiving power from an electrical grid. The water heater includes a heating element, a controller, and a first control circuit. The first control circuit including an energizing terminal and a microprocessor. The method includes connecting an energizing terminal of the first control circuit between a power output terminal of the controller and the heating element, receiving driving power from the controller based on a temperature signal. The method also includes receiving control signals from the controller based on electrical grid information, and selectively energizing the heating element, by the microprocessor of the first control circuit and through the energizing terminal of the first control circuit based on the control signals.

Abstract: System and method for grid load-up dual set point. The invention provides a method of operating a water heater having a tank configured to store water. The method includes heating, via a first heating element, a first portion of the water to a first temperature set point. The method also includes heating, via a second heating element, a second portion of the water to a second temperature set point, the second temperature set point being greater than the first temperature set point. The method additionally includes receiving a load-up signal from a grid controller, and heating, via the first heating element, the first portion of the water to the second temperature set point upon receiving he load-up signal.

Abstract: A water heater including a tank, first and second heating elements, first and second temperature sensors, a communication module, and a controller. The controller is operable to determine a first temperature value related to a first temperature sensed by the first temperature sensor, determine a second temperature value related to a second temperature sensed by the second temperature sensor, and receive a command from the external controller. When the received command is a first command, the controller control current to the first heating element based on the first temperature value traversing a first set point, and controls current to the second heating element based on the second temperature value traversing a second set point. When the received command is a second command, the controller controls current only to the first heating element and not the second heating element, the control being based on the first temperature value.

Abstract: A flame rod analysis system, methods for determining a condition of a flame and a flame rod, and circuits for determining a condition of a flame and a flame rod. The flame rod analysis system comprises energy storage connectable to a flame rod, a pulsed source connected to the energy storage and providing a voltage pulse or a current pulse, and a buffer to allow a processor to measure a buffered voltage at various time points. Flame rod analysis systems can distinguish between various flame conditions (no flame, low flame, etc.) while simultaneously characterizing the condition of the flame rod (shorted to ground, contaminated, etc.). Some flame rod analysis systems can directly measure the resistance of the flame rod.

Abstract: A water heater that includes a tank for holding water, a heat source, a temperature sensor, a communication module operable to communicate with an external controller remote from the water heater, and a controller including a processor and a computer readable memory storing instructions that, when executed by the processor, cause the controller to operate the water heater. The communication module receives commands from the external controller for further operating the water heater.

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 water heater that includes a tank for holding water, a heat source, a temperature sensor, a communication module operable to communicate with an external controller remote from the water heater, and a controller including a processor and a computer readable memory storing instructions that, when executed by the processor, cause the controller to operate the water heater. The communication module receives commands from the external controller for further operating the water heater.

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 water heater venting system, the water heater venting system comprising a main exhaust vent; and a first water heater in communication with a second water heater. The first water heater including an inlet, a blower assembly including a motor, an exhaust vent coupled to the main exhaust vent, a fluid flowpath created by fluid communication between the inlet, the blower assembly, and the exhaust vent, a sensor positioned along the fluid flowpath, and a controller electrically coupled to the sensor and the motor of the blower assembly, the controller controlling the speed of the motor based on at least one of an input from the sensor and an input from the second water heater.