A water heater system and method of operating such a system are disclosed herein. In an example embodiment, the water heater system includes a heat exchanger. a heat source inlet by which heated heating fluid can be provided to the heat exchanger, a heat source outlet by which cooled heating fluid can be communicated from the heat exchanger, a water supply inlet by which supply water can be provided to the heat exchanger, and a water supply outlet by which heated water can be communicated from the heat exchanger. Additionally, the system includes a controller, a water supply outlet temperature sensor, a water supply flowmeter, and an actuator. The controller is configured to generate control signals based at least indirectly upon temperature measurements and flow measurements and to provide the control signals to the actuator to regulate a fluid flow of the heated heating fluid into the heat exchanger.

The disclosed technology includes systems and methods for controlling a water heater. The disclosed systems can be configured to receive temperature data from a temperature sensor, receive flow rate data from a flow rate sensor, and receive a temperature setting. The systems can calculate a heat load rate based on at least the temperature data, the flow rate data, and the temperature setting, and can compare the heat load rate to a predetermined threshold setting. The systems can output instructions to perform a fast corrective action in response to the determination that the heat load is changing at a rate (i.e. the heat load rate) greater than, less than, or equal to the predetermined threshold setting.

The disclosed technology includes systems and methods for controlling a water heater. The disclosed systems can be configured to receive temperature data from a temperature sensor, receive flow rate data from a flow rate sensor, and receive a temperature setting. The systems can calculate a heat load rate based on at least the temperature data, the flow rate data, and the temperature setting, and can compare the heat load rate to a predetermined threshold setting. The systems can output instructions to perform a fast corrective action in response to the determination that the heat load is changing at a rate (i.e. the heat load rate) greater than, less than, or equal to the predetermined threshold setting.

The disclosed technology includes systems and methods for controlling a water heater. The disclosed systems can be configured to receive temperature data from a temperature sensor, receive flow rate data from a flow rate sensor, and receive a temperature setting. The systems can calculate a heat load rate based on at least the temperature data, the flow rate data, and the temperature setting, and can compare the heat load rate to a predetermined threshold setting. The systems can output instructions to perform a fast corrective action in response to the determination that the heat load is changing at a rate (i.e. the heat load rate) greater than, less than, or equal to the predetermined threshold setting.

A water heater system and method of operating such a system are disclosed herein. In an example embodiment, the water heater system includes a heat exchanger. a heat source inlet by which heated heating fluid can be provided to the heat exchanger, a heat source outlet by which cooled heating fluid can be communicated from the heat exchanger, a water supply inlet by which supply water can be provided to the heat exchanger, and a water supply outlet by which heated water can be communicated from the heat exchanger. Additionally, the system includes a controller, a water supply outlet temperature sensor, a water supply flowmeter, and an actuator. The controller is configured to generate control signals based at least indirectly upon temperature measurements and flow measurements and to provide the control signals to the actuator to regulate a fluid flow of the heated heating fluid into the heat exchanger.

A storage type heat pump hot water supplying apparatus includes: control circuitry to control a compressor frequency and a pump rotational speed, the compressor frequency being an operating frequency of the compressor, the pump rotational speed being a rotational speed of a water pump. The control circuitry is configured to control, in a heat accumulating operation for accumulating hot water in the hot water storage tank, the pump rotational speed so that the actual hot water discharge temperature becomes equal to a target hot water discharge temperature. The heat accumulating operation includes a first operation and a second operation after the first operation. The compressor frequency in the first operation is higher than the compressor frequency in the second operation. The target hot water discharge temperature in the first operation is lower than the target hot water discharge temperature in the second operation.

A storage type heat pump hot water supplying apparatus includes: control circuitry to control a compressor frequency and a pump rotational speed, the compressor frequency being an operating frequency of the compressor, the pump rotational speed being a rotational speed of a water pump. The control circuitry is configured to control, in a heat accumulating operation for accumulating hot water in the hot water storage tank, the pump rotational speed so that the actual hot water discharge temperature becomes equal to a target hot water discharge temperature. The heat accumulating operation includes a first operation and a second operation after the first operation. The compressor frequency in the first operation is higher than the compressor frequency in the second operation. The target hot water discharge temperature in the first operation is lower than the target hot water discharge temperature in the second operation.

An ohmic heater for heating a conductive fluid has a plurality of electrodes mounted to a structure with spaces between the electrodes. The electrodes (14) are selectively connect to poles (38, 40) of a power supply, so that some electrodes are connected to the poles and others remain isolated from the poles. Shunting switches are provided for connecting two or more of the isolated electrodes to one another. The shunting switches allow formation of a large number of different connection schemes having a variety of different electrical conduction paths through fluid in the spaces and a variety of resistances between the poles with relatively few electrodes and spaces.

A water heater appliance may include a casing, a tank, a temperature sensor, a heating system, and a controller. The controller may be in operative communication with the heating system. The controller may be configured to initiate a heating cycle. The heating cycle may include determining a future standby event and determining a contemporary depletion state from a plurality of set depletion states. The plurality of set depletion states may include a steady state and one or more depleted states. The heating cycle may further include calculating a recharge period according to a set formula corresponding to the determined contemporary depletion state and directing, prior to the future standby event, the water heater appliance to the steady state based on the recharge period.

A water heater appliance may include a casing, a tank, a temperature sensor, a heating system, and a controller. The controller may be in operative communication with the heating system. The controller may be configured to initiate a heating cycle. The heating cycle may include determining a future standby event and determining a contemporary depletion state from a plurality of set depletion states. The plurality of set depletion states may include a steady state and one or more depleted states. The heating cycle may further include calculating a recharge period according to a set formula corresponding to the determined contemporary depletion state and directing, prior to the future standby event, the water heater appliance to the steady state based on the recharge period.