A freeze protection system is provided that includes a first valve configured to be coupled with an inlet of a water heater, such as a tankless water heater; a second valve configured to be coupled with an outlet of the water heater; and a valve actuator configured to automatically actuate the first valve and the second valve to permit water to drain from the water heater when (1) electric power is lost to the water heater, and (2) a temperature of a fluid in or around the water heater is less than or equal to a predetermined low temperature threshold.

A freeze protection system is provided that includes a first valve configured to be coupled with an inlet of a water heater, such as a tankless water heater; a second valve configured to be coupled with an outlet of the water heater; and a valve actuator configured to automatically actuate the first valve and the second valve to permit water to drain from the water heater when (1) electric power is lost to the water heater, and (2) a temperature of a fluid in or around the water heater is less than or equal to a predetermined low temperature threshold.

A water heating system can include a first tank-based water heater having a first inlet line and a first outlet line, where the first inlet line provides unheated water to the first tank, and where the first outlet line draws heated water from the first tank. The system can also include a first tankless water heater having a second outlet line, where the second outlet line of the first tankless water heater provides the heated water to a first heated water demand. The system can also include a first valve that controls an amount of the unheated water flowing through the first inlet line to the first tank-based water heater. The system can further include a controller operatively coupled to the first valve, where the controller controls a position of the first valve based on the first heated water demand and a first capacity of the first tankless water heater.

A water heater appliance, as provided herein, may include a casing, a tank, an inlet conduit, an electric heating system, and a controller. The tank may be disposed within the casing, the tank defining an inlet and an outlet. The inlet conduit may be mounted to the tank at the inlet of the tank. The electric heating system may be in thermal communication with the tank to heat water within the tank. The controller may be in operative communication with the electric heating system. The controller may be configured to initiate a responsive-heating cycle. The responsive heating cycle may include detecting expiration of a dormant event at the water heater appliance, initiating a randomized delay period in response to detecting expiration of the dormant event, and initiating activation of the water heater appliance following the delay period.

A system and a method for controlling an electrical water heater as per a load shedding request signal are disclosed. A temperature sensor is positioned so as to measure a water temperature in a lower area of a tank of the water heater to be controlled. 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, and 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 the load shedding request signal and only if the salubrity index meets a preestablished criterion.

A fluid heater includes a heating circuit, a temperature monitoring circuit, a controller, and an overheat sensing element. The controller is disposed in a control unit and is in circuit communication with a temperature gauge and a power supply switch, the controller being configured to operate the power supply switch in response to feedback from the temperature gauge to maintain the heater at a setpoint temperature. The overheat sensing element is disposed in a heater housing proximate to a thermal fuse and is in circuit communication with the controller to provide an indication to the controller when the overheat sensing element reaches an overheat temperature lower than the critical temperature. The controller is configured to operate the power supply switch to reduce or shut off power to the heating element in response to receiving the indication that the overheat sensing element has reached the overheat temperature.

A water heating system can include a first tank-based water heater having a first inlet line and a first outlet line, where the first inlet line provides unheated water to the first tank, and where the first outlet line draws heated water from the first tank. The system can also include a first tankless water heater having a second outlet line, where the second outlet line of the first tankless water heater provides the heated water to a first heated water demand. The system can also include a first valve that controls an amount of the unheated water flowing through the first inlet line to the first tank-based water heater. The system can further include a controller operatively coupled to the first valve, where the controller controls a position of the first valve based on the first heated water demand and a first capacity of the first tankless water heater.

A water heating system can include a first tank-based water heater having a first inlet line and a first outlet line, where the first inlet line provides unheated water to the first tank, and where the first outlet line draws heated water from the first tank. The system can also include a first tankless water heater having a second outlet line, where the second outlet line of the first tankless water heater provides the heated water to a first heated water demand. The system can also include a first valve that controls an amount of the unheated water flowing through the first inlet line to the first tank-based water heater. The system can further include a controller operatively coupled to the first valve, where the controller controls a position of the first valve based on the first heated water demand and a first capacity of the first tankless water heater.

A water heating system can include a first tank-based water heater having a first inlet line and a first outlet line, where the first inlet line provides unheated water to the first tank, and where the first outlet line draws heated water from the first tank. The system can also include a first tankless water heater having a second outlet line, where the second outlet line of the first tankless water heater provides the heated water to a first heated water demand. The system can also include a first valve that controls an amount of the unheated water flowing through the first inlet line to the first tank-based water heater. The system can further include a controller operatively coupled to the first valve, where the controller controls a position of the first valve based on the first heated water demand and a first capacity of the first tankless water heater.

A fluid heater includes a heating circuit, a temperature monitoring circuit, a controller, and an overheat sensing element. The controller is disposed in a control unit and is in circuit communication with a temperature gauge and a power supply switch, the controller being configured to operate the power supply switch in response to feedback from the temperature gauge to maintain the heater at a setpoint temperature. The overheat sensing element is disposed in a heater housing proximate to a thermal fuse and is in circuit communication with the controller to provide an indication to the controller when the overheat sensing element reaches an overheat temperature lower than the critical temperature. The controller is configured to operate the power supply switch to reduce or shut off power to the heating element in response to receiving the indication that the overheat sensing element has reached the overheat temperature.