Combined Air Handling Unit

Combined Air Handling Unit Installation

1. All structural types of air-conditioning units shall be installed on a level foundation.
2. Sufficient space shall be left around the unit — especially on the side with the unit's piping and the fan/motor access door — to facilitate daily inspection and periodic maintenance of the unit.
3. The condensate outlet must first be connected to a "U"-shaped drain trap, and only then connected to the external piping.
4. When connecting the coil's inlet and outlet water pipes, apply force evenly and avoid excessive force so as not to damage the coil.
5. The air-conditioning unit's motor shall be connected to a power supply with overload protection and provided with earthing (ground) protection.
6. A flexible connection shall be used between the air-conditioning unit and the external ductwork to avoid transmission of vibration.

Unit Operation

1. Before each operation of the unit, check all valves in its water circuit and air duct, and ensure they are in normal operating condition.
2. The connection, operation, and transmission of moving parts such as the rotor, fan, and motor shall be regularly inspected and promptly adjusted.
3. The primary filter shall be cleaned with clean water or a cleaning agent according to the degree of fouling; the cleaning frequency depends on the operating environment.
4. The medium-efficiency filter shall be cleaned or replaced when its resistance rises to twice the initial resistance.
5. When the unit is not in operation in winter, the water in the coil shall be drained. When the unit continues to operate in winter but stops briefly, the water in the coil must be kept continuously flowing and the fresh-air damper closed, to avoid freeze damage to the coil. For long-term shutdown, the water in the coil shall be drained.
6. The chilled water and hot water shall be clean softened water. Every two years of unit operation, the scale inside the coil shall be removed by chemical means, and the fouling on the fin surface shall be cleaned with compressed air or water.
7. The steam valve of the steam coil must be closed before the fan stops.
8. The steam valve of the steam humidifier must be closed before the fan stops.
9. The electric heating must be turned on only after the fan starts, and turned off 5 minutes before the fan stops; the overheat protection switch of the electric heater must be incorporated into the electric-heating control circuit.