A heating installation comprising: a first circuit (C1); a second circuit (C2); a first heat pump (4) for heating the medium in the first circuit; a heat exchanger (10) which is arranged in the second circuit and connected between a condenser (4b) and an expansion valve (4d) of the first heat pump; a second heat pump (11) arranged for heating a medium by absorbing heat energy from the medium in the second circuit; and a first and a second accumulator tank (A1, A2) arranged in series in the second circuit for accumulating the medium in the second circuit. The accumulator tanks are alternately connectable to the second heat pump in order to allow medium to circulate between the first accumulator tank and the evaporator of the second heat pump in a first operating situation and allow medium to circulate between the second accumulator tank and the evaporator of the second heat pump in a second operating situation.

A method for constructing a water circulation device including a water circulation circuit that circulates water heat-exchanged with a refrigerant heated by a heat pump includes: installing a heater in the water circulation device in contact with the water; depositing scale from the water on the heater by heating the heater while circulating the water in the water circulation circuit; and removing the heater from the water circulation device after the depositing.

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.

An outdoor unit includes an air heat exchanger; a compressor; a water heat exchanger; an expansion valve; a fan that moves air outside the outdoor unit into the air heat exchanger; a motor that rotates the fan; a power device used for driving the compressor; a heat sink located in a space that is an extension portion beyond the air heat exchanger, of a channel of air moved by rotation of the fan during heating of the water from outside the outdoor unit into the air heat exchanger, where the heat sink dissipates heat generated by the power device during driving of the compressor; and a control unit that provides control, upon completion of a water heating operation, to drive the compressor, to open the expansion valve, and to rotate the fan in the same direction as the rotation direction of the fan during heating of the water.

A method of heating water in a water storage tank. The method includes: selecting an outlet port and an inlet port from at least three ports located in the tank at different heights along a vertical direction. The outlet port is below the inlet port. The method further includes extracting water from the outlet port, supplying the extracted water to an external heat exchanger configured for heating the extracted water, and delivering heated water from the heat exchanger to the selected inlet port.

The present disclosure relates to a method for preventing freezing when a four-way valve in a heat pump water heater is failed, including following acts: S1, it is judged that whether current water temperature T is lower than a preset minimum temperature T.sub.min for the water tank, if yes, perform act S2; if no, perform act S1 again; S2, it is judged that whether a cooling rate Td of the current water temperature T is greater than or equal to a preset rate T; or, it is judged that whether the current water temperature T satisfies T<T.sub.mina and whether T<T.sub.mina stands for a first time period t1, in which a is a limit value of a temperature difference; if at least one yes, perform act S3, otherwise, return to act S1; S3, a heat pump system is controlled to stop and an electric auxiliary heating system is started.

A method of controlling a heat up of a domestic hot water tank, whereby tank temperatures are measured. The tank temperatures are fed into a control unit and a heating device is activated to heat up water in the tank when the control unit calls for heat. The method comprises a step of feeding an incoming cold-water temperature value into the control unit and generating a parameter effected by this incoming cold-water temperature. The tank temperature is measured and is related to the thermal energy content of the tank, whereby the tank temperature is measured with an integral water temperature sensor mounted to the tank, further effecting the parameter. It processes then a call for heat depending on a comparison of a set point value with the parameter generated from the tank temperature and the measured cold-water temperature.

An air treatment device (1) and a method for heating of aft, in a heating mode, at an air handling unit (2), which comprises a heat recovery device (3). The device further comprises a heat pump (6), comprising an evaporator (7), arranged in a first air stream (4), in the flow direction, after the heat recovery device (3), and a condenser (8) arranged in a second air stream (5), in the flow direction, after the heat recovery device (3). The device further comprises an auxiliary heater (9) for supplying, in addition to the recovered energy, external heat energy. The auxiliary heater (9) is positioned in the first air stream (4), in the flow direction, after the heat recovery device (3) and before the evaporator (7) for heating and thereby the heat pump (6) operation is maintained and a better total efficiency for the plant is achieved.

A water heating system for a domestic hot water tank, the system including: a heat pump adapted to provide heat energy; and a heat exchanger comprising a coil of thermally conductive material arranged such that a diameter of the coil is approximately between five and six times greater than a diameter of the thermally conductive material and the heat exchanger is adapted to be installed in the domestic hot water tank and operationally coupled to the heat pump.

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.