Hybrid multi-air conditioning system

A hybrid multi-air conditioning system, comprising:

• a hot-water unit that exchanges heat between refrigerant and water;
• at least one indoor unit installed indoors and comprising an indoor heat exchanger and an indoor unit expansion valve;
• and
• an outdoor unit connected to the indoor unit and the hot-water unit via a refrigerant pipeline and comprising an outdoor heat exchanger, a compressor, and an outdoor unit expansion valve, wherein, when an abnormal refrigerant enters either the at least one indoor unit or the outdoor unit according to an operation mode, the abnormal refrigerant is shut off from the hot-water unit and the at least one indoor unit or the outdoor unit which operates as a condenser, wherein the hot-water unit comprises:
• a water tank that stores the water;
• a hot-water heat exchanger wound on an outer wall of the water tank, that transfers heat between the refrigerant and the water while allowing the refrigerant to flow inside;
• and
• a hot-water expansion valve that shuts off the refrigerant condensed by the hot-water heat exchanger or allows the same to flow therethrough, and wherein it is determined whether the abnormal refrigerant is discharged from the hot-water unit based on front and rear end temperatures of the refrigerant passing through the hot-water expansion valve.