Mitsubishi Electric MXZ-8C48NA Manuel D'installation page 9

5. Installing the refrigerant piping
D
A Front piping cover
B Piping cover
C Stop valve
D Service panel
E
(1)
Fig. 5-8
(2)
Fig. 5-9
A Valve F Completely closed
B Unit side G Completely open
C Service port H Refrigerant piping side (On-site installation)
D Handle I
E Cap J Wrench hole
Remove the service panel D (3 screws) and the front piping cover A (2 screws) and
rear piping cover B (4 screws).
1 Perform refrigerant piping connections for the indoor/outdoor unit when the
outdoor unit's stop valve is completely closed.
2 Vacuum-purge air from the indoor unit and the connection piping.
Evacuation
Evacuate with the valve of the outdoor unit closed and evacuate both the connec-
tion piping and the indoor unit from the service port provided on the valve of the
C
outdoor unit using a vacuum pump. (Always evacuate from the service port of both
liquid pipe and gas pipe.) After the vacuum reaches 650 Pa [abs] [0.0943 psi/5
Torr], continue evacuation for at least one hour or more. Then, stop the vacuum
pump and leave it for 1 hour. Ensure the degree of vacuum has not increased.
B
the liquid pipe, and adjust the gas piping to obtain an appropriate amount of the
refrigerant during operation.
3 After connecting the refrigerant pipes, check the connected pipes and the
A E
indoor unit for gas leaks. (Refer to 5.8. Refrigerant pipe airtight testing method)
4 Vacuumize the refrigerant lines through the service port of the liquid and gas
stop valves. And then open the stop valves completely (for both the liquid and
gas stop valves). This will completely connect the refrigerant lines of the indoor
and outdoor units.
5 Use sealant to seal the ends of the thermal insulation around the pipe connec-
tion sections to prevent water from entering the thermal insulation.
Refrigerant pipes are protectively wrapped
or after connecting the pipes. Cut out the knockout in the pipe cover following the
groove and wrap the pipes.
Pipe inlet gap
(If the gaps are not closed, noise may be emitted or water and dust will enter the
unit and breakdown may result.)
Note:
<Triple Evacuation>
below.
the refrigerant pipe joints.
operating with the valve closed, abnormal pressure will be imparted to the high- or
low-pressure side of the refrigerant circuit, giving damage to the compressor, etc.
Determine the amount of additional refrigerant charge (refer "5.3. Addition of refrig-
erant"), and charge refrigerant additionally through the service port after complet-
ing piping connection work.
Method of completely opening the stop valve
The stop valve opening method varies according to the outdoor unit model. Use the
appropriate method to open the stop valves.
(1) Gas side (Fig. 5-8)
1 Remove the cap, pull the handle toward you and rotate 1/4 turn in a counterclock-
wise direction to open.
2 Make sure that the stop valve is open completely, push in the handle and rotate
the cap back to its original position.
(2) Liquid side (Fig. 5-9)
1 Remove the cap and turn the valve rod counterclockwise as far as it will go with
the use of a 4 mm [3/16"] hexagonal wrench. Stop turning when it hits the stopper.
2 Make sure that the stop valve is open completely and rotate the cap back to its
original position.
Finally, seal in with the liquid refrigerant through
and control valves will be damaged.
nection sections of the outdoor unit.
lines.
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.
manifold gauges must not be used to measure vacuum. A micron gauge
must be used at all times.
-
-
microns for a minimum of 1 hour.
10 kgf·cm
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