Abstract: An air conditioning system (1) includes an outdoor subsystem, an indoor subsystem and a power module (3) for driving a cooling medium. The outdoor subsystem is configured with a plurality of parallel branches (4) and said branches (4) comprise a branch inlet and a branch outlet, each branch (4) is configured with an outdoor unit (5) and a first control valve (6). The air conditioning system includes a controller (7), a first pressure sensor (8) and a second pressure sensor (9), the controller (7) comprises a first pressure difference determination module that commuicates with the first pressure sensor and the second pressure sensor, and a first control module of the first pressure difference that communicates with the first pressure difference determination module and the first control valve (4), where the first pressure difference determination module determines the pressure difference between the outlet and the inlet of the branches.

Abstract: Heat pump systems and methods for providing chilled/hot liquid for air-conditioning and domestic hot-water, are provided. The heat pump systems include a first heat exchanger, a second heat exchanger and a third heat exchanger (e.g., a hot-water heat exchanger) that share at least one expansion valve disposed at a downstream position of the hot-water heat exchanger. The at least one expansion valve is disposed between the hot-water heat exchanger and the first and second heat exchangers. The heat pump systems can provide six operation modes, including a cooling mode, a heating mode, a water-heating mode, a heat-recovery mode, a simultaneous heating and water heating mode, and a defrost mode.