Horizontal fan coil units are mainly composed of fans, heat exchangers (coils), condensate trays, casings, and controllers, suitable for centralized air conditioning systems. They feature advanced design, a wide variety, superior performance, and are widely used in various hotels, apartments, restaurants, and commercial buildings that require low noise and flexible temperature control. The main control parameters for horizontal fan coil units include rated airflow, outlet static pressure, input power, rated cooling capacity, rated heating capacity, noise, and water resistance. For fan coil units in a two-pipe water system (used for heating/cooling conversion based on season or air conditioning area), only a single coil set is configured, with a dual-purpose model for heating/cooling in summer and winter. For fan coil units in a four-pipe water system (used for frequent heating/cooling conversion), a combined model with both heating and cooling coil sets should be configured.