A heating system retrofitted to be operable through multiple heat stages at a constant fuel-air mixture includes a tube heat exchanger having a plurality of burners, a combustion air blower (CAB) having an exhaust vent connected with the plurality of burners, the CAB operable at a first speed and a second speed, a first valve connecting a fuel source to a first subset of the plurality of burners, and a second valve connecting a fuel source to a second subset of the plurality of burners.

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.

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.

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.

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.

A modulating heating system includes a tube heat exchanger having a plurality of burners, a combustion air blower (CAB) having an exhaust vent connected with the plurality of burners, the CAB operable at a first speed and a second speed, a first valve connecting a fuel source to a first subset of the plurality of burners, and a second valve connecting a fuel source to a second subset of the plurality of burners, wherein the first and second valves each have a low fire rate and a high fire rate. The heat exchanger is operable through multiple heat stages at a constant fuel-air mixture.

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.

Systems and methods are provided for wireless cascading water heater systems. The wireless cascading water heater system may include several water heaters that may include one or more of a tankless water heater, a boiler, or a combination boiler, for example. One or more of the water heaters may communicate with a remote controller and/or a user device. The water heaters may further be in wireless communication with one another. One water heater may be designated the lead water heater and a second water heater may be designated the backup water heater. The lead water heater may oversee operation of the follower water heaters in response to a hot water demand. A hierarchical order may be determined for selecting which water heaters will respond to hot water demand and in what order. The hierarchical order may be based on the age of the water heater, burn time for the water heater for optimization and efficiency purposes.

A packaged heating and/or cooling unit for a production module for a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The packaged unit includes a heat pump configured to provide heating and/or cooling; a connection to a piping distribution system to selectively connect to a hot fluid circuit and/or a cold fluid circuit; and a controller. The controller is configured to connect to and receive a signal from a building automation system for a heating requirement or a cooling requirement, and further configured to selectively control connection to either the hot fluid circuit or the cold fluid circuit and independently control the packaged heating and/or cooling unit based on the signal from the building automation system for either the heating requirement or the cooling requirement.

A modulating heating system includes a tube heat exchanger having a plurality of burners, a combustion air blower (CAB) having an exhaust vent connected with the plurality of burners, the CAB operable at a first speed and a second speed, a first valve connecting a fuel source to a first subset of the plurality of burners, and a second valve connecting a fuel source to a second subset of the plurality of burners, wherein the first and second valves each have a low fire rate and a high fire rate. The heat exchanger is operable through multiple heat stages at a constant fuel-air mixture.