A single unit HVAC system for a unit in a multi-unit building comprises a first heat exchanger thermally connected to a riser stack, a plurality of fan coils, each fan coil comprising a unit heat exchanger and a motor and fan assembly wherein, in operation, the motor and fan assembly delivers air to a location in the unit, and a closed loop fluid flow path extending between the first heat exchanger and the plurality of unit heat exchangers. In operation, the first heat exchanger exchanges heat between the riser stack fluid and the closed loop fluid, each unit heat exchanger exchanges heat between the closed loop fluid and air that is delivered to a different room in the unit.

An air conditioning system and a control method thereof. The air conditioning system includes a main circuit and a first subcooling circuit, wherein the main circuit has: a main compressor and an injector; a gas cooler and a gas-liquid separator connected between the main compressor and the injector; and a main throttling element and an evaporator connected between the gas-liquid separator and the injector; and wherein the first subcooling circuit has: a first subcooling compressor, a first condenser, a first subcooling throttling element and a first subcooler connected in sequence; wherein the first subcooler is further disposed in a flow path between the outlet of the injector and the gas-liquid separator.

Provided is an air conditioning apparatus. The air conditioning apparatus includes a heat exchanger in which the refrigerant and the water are heat-exchanged with each other, a high-pressure guide tube extending from a high-pressure gas tube of an outdoor unit so as to be connected to one side of the heat exchanger, a low-pressure guide tube extending from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube, a liquid guide tube extending from a liquid tube of the outdoor unit so as to be connected to the other side of the heat exchanger, a bypass tube configured to connect a bypass branch point of the high-pressure gas tube to a bypass combination point of the liquid guide tube to bypass a high-pressure refrigerant existing in the high-pressure tube to the liquid guide tube, and a bypass valve installed in the bypass tube.

An HVAC system is provided. Embodiments of the present disclosure generally relate to an HVAC system in which multiple indoor units are coupled to central outdoor unit, where at least one of the indoor units is configured to provide conditioned air through ductwork and at least one indoor unit is configured to provide conditioned air without ductwork. Moreover, a gas furnace can be provided in the system, for harsher environments that benefit from more robust heating. Additional systems, devices, and methods are also disclosed.

A method of operating a heating and cooling system includes (1) providing a heating and/or cooling apparatus having first and second heat exchangers, (2) providing a conduit module modularly coupled to the heating and/or cooling apparatus and adapted to be coupled to a plurality of fluid circuits for heating or cooling loads, and (3) operating a control system configured to operate the conduit module in a heating or cooling mode. The conduit module is positioned between the heating and/or cooling apparatus and the plurality of fluid circuits. The conduit module includes first, second, and third supply conduits and first, second, and third return conduits, to convey first, second, and source fluids to and from respective first, second, and source fluid circuits. The conduit module includes first, second, third, and fourth three-way valves to selectively regulate flow of the first, second, and source fluids.

A method of operating a heating and cooling system includes (1) providing a heating and/or cooling apparatus having first and second heat exchangers, (2) providing a conduit module modularly coupled to the heating and/or cooling apparatus and adapted to be coupled to a plurality of fluid circuits for heating or cooling loads, and (3) operating a control system configured to operate the conduit module in a heating or cooling mode. The conduit module is positioned between the heating and/or cooling apparatus and the plurality of fluid circuits. The conduit module includes first, second, and third supply conduits and first, second, and third return conduits, to convey first, second, and source fluids to and from respective first, second, and source fluid circuits. The conduit module includes first, second, third, and fourth three-way valves to selectively regulate flow of the first, second, and source fluids.

A method to control a carrier fluid through a service line (5) of a conditioning and/or heating system (1). The service line includes a heat exchange unit (7), a flow regulator (8), temperature sensors (9; 9a, 9b) detecting a temperature difference (ΔT.sub.i) between the carrier fluid in a first section (5a) of the service line (5) upstream of said heat exchange unit (7) and carrier fluid in a second section (5b) of the service line (5) downstream of the same heat exchange unit (7). The method includes calculating a value assumed by a control parameter (Pc) which is a function of at least one or more values assumed by the temperature difference in the transition of the flow regulator from a first to a second operating condition, for then determining whether the value of the control parameter (Pc) is higher than a threshold (S).

A method to control a carrier fluid through a service line (5) of a conditioning and/or heating system (1). The service line includes a heat exchange unit (7), a flow regulator (8), temperature sensors (9; 9a, 9b) detecting a temperature difference (ΔT.sub.i) between the carrier fluid in a first section (5a) of the service line (5) upstream of said heat exchange unit (7) and carrier fluid in a second section (5b) of the service line (5) downstream of the same heat exchange unit (7). The method includes calculating a value assumed by a control parameter (Pc) which is a function of at least one or more values assumed by the temperature difference in the transition of the flow regulator from a first to a second operating condition, for then determining whether the value of the control parameter (Pc) is higher than a threshold (S).

An air-conditioning apparatus includes a refrigeration circuit, a first shut-off device provided at a pipe connecting a heat-source-side heat exchanger and an expansion device, a refrigerant leak detection device, and a controller. The controller controls a flow switching device to switch a connection state between a first connection state in which a discharge side of a compressor is connected to the heat-source-side heat exchanger, and a second connection state in which a suction side of the compressor is connected to the heat-source-side heat exchanger via an accumulator. When a refrigerant leak is detected, the controller performs a refrigerant retrieval operation and a refrigerant transfer operation.

An air-conditioning apparatus includes a refrigeration circuit, a first shut-off device provided at a pipe connecting a heat-source-side heat exchanger and an expansion device, a refrigerant leak detection device, and a controller. The controller controls a flow switching device to switch a connection state between a first connection state in which a discharge side of a compressor is connected to the heat-source-side heat exchanger, and a second connection state in which a suction side of the compressor is connected to the heat-source-side heat exchanger via an accumulator. When a refrigerant leak is detected, the controller performs a refrigerant retrieval operation and a refrigerant transfer operation.