An apparatus for heating water has a tank for storing water and an air conditioning system that defines a refrigerant flow path through which refrigerant flows. The refrigerant flow path passes through the heat exchanger so that refrigerant heat is contributed to the tank. A control system controls operation of the water heating apparatus.

A domestic water heating group includes a heat source; storage tank. A heat exchanger includes inlet and outlet sections, the the inlet and outlet being in fluid communication with: a water supply system, a water usage system and the tank. The water is heated to, towards the tank, a storage temperature TAC and/or towards the usage system at a supply temperature TER, mixer group is upstream of the inlet of the exchanger group and has first and second inlet ports connected to the supply system, tank, exchanger group The mixer receives the domestic water, at a low temperature TIN, the heated domestic water at the second inlet port, and mixes the water thus received and provides at the outlet port, in fluid connection with the exchanger group, the mixed domestic water having an intermediate temperature TINT included between the temperature TIN and the temperature TAC.

Provided is a heat pump hot water supply apparatus configured to directly supply water heated by a gas cooler to a utilization side. The heat pump hot water supply apparatus is configured to execute operation modes including a first operation mode and a second operation mode. The first operation mode includes causing the water heated by the gas cooler to return to a water tank as intermediate-temperature water. The second operation mode is an operation mode to be performed after the first operation mode, and includes mixing the water heated by the gas cooler and the intermediate-temperature water in the water tank, and directly supplying the mixed water to the utilization side.

A system for heating a first fluid flow from a first temperature to a second temperature, the system including a hot water supply line for receiving the first fluid flow at a first end and exhausting the first fluid flow at a second end; and a heating system including a heat engine, a thermal battery and a heat exchanger, wherein the thermal battery is configured to be replenished at a point of heat transfer by the heat engine and the hot water supply line is configured to receive heat from the thermal battery via the heat exchanger to elevate the temperature of the first fluid flow from the first temperature to the second temperature.

A heat pump water heater has a tank, a heat source, and a heat pump system. The heat pump system has a refrigerant path, at least a portion of which is in thermal communication with the water tank volume so that heat transfers from refrigerant to the water tank volume. A fan causes air to flow through a housing, and another portion of the refrigerant path includes an evaporator in the housing. The fan is within the housing and may further be within a second housing. The first housing may comprise a baffle to direct air flow. The fan may be a variable speed fan in communication with a controller, so that the controller controls the fan speed depending on a temperature of the refrigerant.

A settings data storage stores unique serial numbers and information regarding a plurality of patterns for alternately switching between normal operation for operating at high capacity and suppressed operation for operating at low capacity each unit time. A pattern specifier determines information for a pattern set in accordance with even and odd serial numbers. A water-heating heat amount determiner determines a heat amount necessary for water heating. A water heating scheduler establishes a water heating plan based on information regarding the pattern determined by the pattern determiner and the water-heating heat amount as determined by the water-heating heat amount determiner. A water heating controller alternately switches between normal operating and suppressed operation to heat water in accordance with the water heating plan established by the water heating scheduler.

In an immediate hot water supply operation mode in which a circulation pump is activated while a hot water supply faucet is closed, a water heating apparatus forms an immediate hot water supply circulation path by an inner path including a water entry path, a heat exchanger, and a hot water output path and an outer path bypassing the hot water supply faucet, as being combined. A controller stores as an actual flow rate value for each immediate hot water supply operation mode, a flow rate detection value by a flow rate sensor at predetermined timing, and calculates a flow rate learning value based on a plurality of stored actual flow rate values. When the flow rate detection value becomes larger than a criterion value set in accordance with the flow rate learning value, use of the hot water supply faucet is detected and the circulation pump is deactivated.

An apparatus for heating water has a tank for storing water and an air conditioning system that defines a refrigerant flow path through which refrigerant flows. The refrigerant flow path passes through the heat exchanger so that refrigerant heat is contributed to the tank. A control system controls operation of the water heating apparatus.

A heat pump water heater has a tank, a heat source, and a heat pump system. The heat pump system has a refrigerant path, at least a portion of which is in thermal communication with the water tank volume so that heat transfers from refrigerant to the water tank volume. A fan causes air to flow through a housing, and another portion of the refrigerant path includes an evaporator in the housing. The fan is within the housing and may further be within a second housing. The first housing may comprise a baffle to direct air flow. The fan may be a variable speed fan in communication with a controller, so that the controller controls the fan speed depending on a temperature of the refrigerant.

A water-heating system, including: a controller; a refrigerant-water heat exchanger for exchanging heat between refrigerant and water; a sensor circuit for measuring a current water temperature of water in a water heater and providing the current water temperature to the controller; a first refrigerant pipe for passing the refrigerant from a refrigerant source to the refrigerant-water heat exchanger; a second refrigerant pipe for passing the refrigerant from the refrigerant-water heat exchanger to the refrigerant source; a first water pipe for passing the water from the water heater to the refrigerant-water heat exchanger; a second water pipe for passing the water from the refrigerant-water heat exchanger to the water heater; and a water pump for pumping water from the water heater to the refrigerant-water heat exchanger via the first water pipe and from the refrigerant-water heat exchanger to the water heater via the second water pipe based on a control signal.