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.

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.

A heater for heating a conductive liquid includes a two-dimensional array of rod-like electrodes (22, 122, 322, 422, 522) extending parallel to one another, an electrical power supply having a plurality of poles, and power switches to connect different ones of the electrodes to different poles so that current flows between the poles through the liquid. The array desirably includes outer electrodes defining the boundary (24, 424) of the array and inner electrodes disposed within this boundary. The array may have regular or irregular spacings between the electrodes. The array can provide numerous different connection schemes to vary the electrical resistance between the poles and thus vary the heating rate. The array can be arranged to provide substantially equal currents through three poles of a three-phase power supply.

A heater for heating a conductive liquid includes a two-dimensional array of rod-like electrodes (22, 122, 322, 422, 522) extending parallel to one another, an electrical power supply having a plurality of poles, and power switches to connect different ones of the electrodes to different poles so that current flows between the poles through the liquid. The array desirably includes outer electrodes defining the boundary (24, 424) of the array and inner electrodes disposed within this boundary. The array may have regular or irregular spacings between the electrodes. The array can provide numerous different connection schemes to vary the electrical resistance between the poles and thus vary the heating rate. The array can be arranged to provide substantially equal currents through three poles of a three-phase power supply.

A heater for heating a conductive liquid includes a two-dimensional array of rod-like electrodes (22, 122, 322, 422, 522) extending parallel to one another, an electrical power supply having a plurality of poles, and power switches to connect different ones of the electrodes to different poles so that current flows between the poles through the liquid. The array desirably includes outer electrodes defining the boundary (24, 424) of the array and inner electrodes disposed within this boundary. The array may have regular or irregular spacings between the electrodes. The array can provide numerous different connection schemes to vary the electrical resistance between the poles and thus vary the heating rate. The array can be arranged to provide substantially equal currents through three poles of a three-phase power supply.

A heater for heating a conductive liquid includes a two-dimensional array of rod-like electrodes (22, 122, 322, 422, 522) extending parallel to one another, an electrical power supply having a plurality of poles, and power switches to connect different ones of the electrodes to different poles so that current flows between the poles through the liquid. The array desirably includes outer electrodes defining the boundary (24, 424) of the array and inner electrodes disposed within this boundary. The array may have regular or irregular spacings between the electrodes. The array can provide numerous different connection schemes to vary the electrical resistance between the poles and thus vary the heating rate. The array can be arranged to provide substantially equal currents through three poles of a three-phase power supply.