The water system type is a small semi-centralized fan-coil system, and all indoor loads are borne by the cold and hot water units. The fan coils in each room are connected to the cold and hot water units through pipes, and they are provided with cold and hot water for cooling and heating. The water system has a flexible layout, good independent adjustability, and very high comfort, which can meet the needs of complex room types for scattered use and independent operation of each room. In addition, the current new type of water system air conditioner is also one of the best solutions for floor heating system applications. Through effective combination with floor heating, it adopts medium and low water temperature and large area low-temperature radiant heating, which is better than traditional fan coil heating systems. More comfortable and energy saving.