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4. Installing the refrigerant piping
en
D
15
B
C
E
A
Fig. 4-3
A Front piping cover
B Rear piping cover
C Stop valve
D Service panel
E Bend radius : 100 mm - 150 mm
4.3. Refrigerant piping (Fig. 4-3)
Remove the service panel D (4 screws) and the front piping cover A (2 screws) and
rear piping cover B (4 screws).
• Powders flaked from some rubber mounts will not cause any problems on the
use of the outdoor unit.
• Do not let a refrigerant pipe make a contact with the baseplate.
Transmission of vibrations from the outdoor unit to indoor may cause sounds.
1 Perform refrigerant piping connections for the indoor/outdoor unit when the out-
door unit's stop valve is completely closed.
2 Vacuum-purge air from the indoor unit and the connection piping.
3 After connecting the refrigerant pipes, check the connected pipes and the indoor
unit for gas leaks. (Refer to 4.4. Refrigerant pipe airtight testing method)
4 A high-performance vacuum pump is used at the stop valve service port to main-
tain a vacuum for an adequate time (at least one hour after reaching –101 kPa (5
Torr)) in order to vacuum dry the inside of the pipes. Always check the degree of
vacuum at the gauge manifold. If there is any moisture left in the pipe, the degree
of vacuum is sometimes not reached with short-time vacuum application.
After vacuum drying, completely open the stop valves (both liquid and gas) for the
outdoor unit. This completely links the indoor and outdoor refrigerant circuits.
• If the vacuum drying is inadequate, air and water vapor remain in the refrigerant
circuits and can cause abnormal rise of high pressure, abnormal drop of low
pressure, deterioration of the refrigerating machine oil due to moisture, etc.
• If the stop valves are left closed and the unit is operated, the compressor and
control valves will be damaged.
• Use a leak detector or soapy water to check for gas leaks at the pipe connec-
tion sections of the outdoor unit.
• Do not use the refrigerant from the unit to purge air from the refrigerant lines.
• After the valve work is completed, tighten the valve caps to the correct torque:
20 to 25 N·m (200 to 250 kgf·cm).
Failure to replace and tighten the caps may result in refrigerant leakage. In
addition, do not damage the insides of the valve caps as they act as a seal to
prevent refrigerant leakage.
5 Use sealant to seal the ends of the thermal insulation around the pipe connection
sections to prevent water from entering the thermal insulation.
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