Embodiments described herein generally relate to a domestic hot water (DHW) preheater operable to supply domestic hot water to a structure and/or to preheat a cold return of a space heating system.

A method of operating a water heater receiving electrical power from an electrical grid. The method includes providing a water heater in a locked state. A digital key module may be communicatively coupled (for example, via wired or wireless communication) to the water heater and used to unlock the water heater placing the water heater into an unlocked state. Such unlocking of the water heater must only be done for such water heaters that are enrolled in a utility demand response program.

An electrical water heater adapted for energy management and a method of controlling the consumption of electrical power from the power supply grid of a utility is described. The bottom resistive heating element of the water heater is a dual element resistive heating element which has a high power rated resistive heating element to heat water and a further low power rated resistive heating element. The power rating of the low power resistive heating element is calculated to be lower than the supply grid diversified mean load. A controller has a communication link with a utility which manages the power supply grid. The utility can control the resistive heating elements of the dual element in such a way, and depending on conditions of the grid, to conserve energy and regulate its frequency thereby resulting in a cost saving to the consumer and the utility. The low power rated resistive heating element is also connectable to an alternative power source.

An electrical water heater adapted for energy management and a method of controlling the consumption of electrical power from the power supply grid of a utility is described. The bottom resistive heating element of the water heater is a dual element resistive heating element which has a high power rated resistive heating element to heat water and a further low power rated resistive heating element. The power rating of the low power resistive heating element is calculated to be lower than the supply grid diversified mean load. A controller has a communication link with a utility which manages the power supply grid. The utility can control the resistive heating elements of the dual element in such a way, and depending on conditions of the grid, to conserve energy and regulate its frequency thereby resulting in a cost saving to the consumer and the utility. The low power rated resistive heating element is also connectable to an alternative power source.

A water heater has a tank and at least one heating element. A switch is disposed in an electric circuit between the heating element and a power source so that, if the switch is in a first state, the circuit is in an electrically conductive state and, if the switch is in a second state, the electric circuit is in an electrically non-conductive state. A controller is in operative communication with the switch and is responsive to a key so that actuation of the controller by the key transitions the switch between the first state and the second state.

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.

A safety system and method to prevent water within a top portion of a tank of an electric water heater to drop below a safe temperature during a load shedding period, other than a full emergency grid failure, by a power provider whereby to prevent the propagation of harmful bacteria in a top portion the tank. A control device monitors the water temperature in the top portion of the tank by the use of a temperature sensor. If the control device detects a temperature of the water in the top portion of the tank inferior to 140 degrees F., it will by-pass the instructions of the power provider and connect power to one or more of the resistive heating elements of the tank until a predetermined temperature above 140 degrees F. is attained before switching off the resistive heating elements.

A controller for an electric booster element in a water heater is described. The electric booster element is powered from mains power and the controller comprises a control module and a capacitive module adapted to store power and supply stored power to the control module. The control module produces a control signal for controlling a relay to supply or restrict mains power supply to said booster element, said control signal depending at least in part on time of use data.

An electrical water heater adapted for energy management and a method of controlling the consumption of electrical power from the power supply grid of a utility is described. The bottom resistive heating element of the water heater is a dual element resistive heating element which has a high power rated resistive heating element to heat water and a further low power rated resistive heating element. The power rating of the low power resistive heating element is calculated to be lower than the supply grid diversified mean load. A controller has a communication link with a utility which manages the power supply grid. The utility can control the resistive heating elements of the dual element in such a way, and depending on conditions of the grid, to conserve energy and regulate its frequency thereby resulting in a cost saving to the consumer and the utility. The low power rated resistive heating element is also connectable to an alternative power source.

An electrical water heater that receives a load shedding request signal uses a temperature sensor that is positioned so as to measure a water temperature in a lower area of a tank of the water heater. A controller continuously determines a salubrity index of the water heater as a function of the temperature measured by the sensor and a time measurement The controller decides to interrupt an electrical power supply of the water heater through a switch so as to interrupt or not interrupt an operation of the water heater upon receipt of the load shedding request signal and only if the salubrity index meets a preestablished criterion.