LG MULTI F Installation Manual page 148

REFRIGERANT PIPING PREPARATION
Vacuum Procedure
Vacuum Procedure
Vacuum drying should be performed from the service port provided on the outdoor unit's service valve to the vacuum pump commonly used
for liquid pipe and the vapor pipe. Vacuum of the pipe and the indoor units should be made from the port of the outdoor unit's service valve
with the service valve closed.
• Never perform air purging using refrigerant; it will damage the outdoor unit.
• Use a vacuum pump that can evacuate to 500 microns.
1. Evacuate the system from the liquid and vapor pipes with a vacuum pump for over two (2) hours and bring the system to 500 microns.
2. Maintain system under that condition for over one (1) hour; if the vacuum gauge rises, the system may contain moisture or a leak.
3. If there is a possibility of moisture in the piping (rainwater may have entered the piping if work was performed during a rainy season or
over an extended period), then:
• Evacuate the system for two (2) hours to 7.3 psi (vacuum break) with nitrogen gas.
• Evacuate it again with the vacuum pump for one (1) hour to 500 microns (vacuum drying).
4. If the system cannot be evacuated to 500 microns, repeat the steps of vacuum break and drying.
5. Finally, after maintaining the system in vacuum for one (1) hour, check if the vacuum gauge rises or not.
Figure 56: Vacuum Procedure Diagram.
Vacuum Pump
• If the primary refrigerant charge is not performed in a reasonable time after the vacuum procedure is complete, wet air may infiltrate the
• Do not perform refrigerant charge while the compressor is operating, otherwise, liquid may leak and subsequently damage the com-
pressor.
• Use a micron gauge to measure vacuum.
• Obtain the precise amount of refrigerant needed using calculations outlined in the following pages. Too much or too little refrigerant may
cause the system to malfunction.
•
•
its gaseous state, its composition changes and the system will not work properly.
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