Mitsubishi Electric Mr.SLIM PUZ-ZM71VHA Manuel D'installation page 10

4. Installing the refrigerant piping
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ZM71
D
A Front piping cover
B Piping cover
C Stop valve
D Service panel
E Bend radius : 100 mm - 150 mm
en
C
B
H
I
J
F
E
A Stop valve <Liquid side>
B Stop valve <Gas side>
C Unit side
D Cap
E Local pipe side
F Pipe cover
G Service port
H Wrench hole
8
C
B
A
E
Fig. 4-3
C
G
A
D
H
I
J
F
E
I Double spanner section
(Do not apply a spanner other than to
this section. Doing so would cause cool-
ant leaks.)
J Seal section
(Seal the end of the heat insulation ma-
terial at the pipe connection section with
whatever seal material you have on hand
so that water does not infiltrate the heat
insulation material.)
Fig. 4-4
4.3. Refrigerant piping (Fig. 4-3)
Remove the service panel D (3 screws) and the front piping cover A (2 screws) and
rear piping cover B (2 screws).
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.
4.4. Refrigerant pipe airtight testing method (Fig. 4-4)
(1) Connect the testing tools.
• Make sure the stop valves A B are closed and do not open them.
• Add pressure to the refrigerant lines through the service port G of the liquid
stop valve A .
(2) Do not add pressure to the specified pressure all at once; add pressure little by
D
little.
1 Pressurize to 0.5 MPa (5 kgf/cm
sure does not decrease.
2 Pressurize to 1.5 MPa (15 kgf/cm
pressure does not decrease.
3 Pressurize to 4.15 MPa (41.5 kgf/cm
perature and refrigerant pressure.
(3) If the specified pressure holds for about one day and does not decrease, the pipes
have passed the test and there are no leaks.
• If the surrounding temperature changes by 1°C, the pressure will change by
about 0.01 MPa (0.1 kgf/cm
(4) If the pressure decreases in steps (2) or (3), there is a gas leak. Look for the
source of the gas leak.
G), wait five minutes, and make sure the pres-
2
G), wait five minutes, and make sure the
2
G) and measure the surrounding tem-
2
G). Make the necessary corrections.
2