Mitsubishi Electric CITY MULTI PUMY-P125 Installation Manual page 8

4. Installing the refrigerant piping
D
A Front piping cover
B Piping cover
C Stop valve
D Service panel
E Bend radius : 100 mm - 150 mm
Fig. 4-4
A
C
D
E
F
G
A Stop valve
B Stop valve
C Service port
D Open/Close section
E Local pipe
Fig. 4-5
(1) (2)
B
B
A
A
E
K
C
C
H
H
Type A Type B
Fig. 4-6
(3)
1
B
C
E
J
H
Type C
Fig. 4-7
8
C
B
A
E
B
H
I
C
F Sealed, same way for gas side
G Pipe cover
H Do not use a wrench here.
Refrigerant leakage may result.
I Use two wrenches here.
D
E
F
G
2
I
4.3. Refrigerant piping (Fig. 4-4)
Remove the service panel D (three screws) and the front piping cover A (two screws)
and rear piping cover B (two 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 coolant circuits.
• 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. 4-5)
(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 C of the stop
valve A and the stop valve B.
(2) Do not add pressure to the specified pressure all at once; add pressure little by little.
1 Pressurize to 0.5 MPa (5 kgf/cm
pressure 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 2 G). Make the necessary corrections.
(4) If the pressure decreases in steps (2) or (3), there is a gas leak. Look for the
source of the gas leak.
4.5. Stop valve opening method
The stop valve opening method varies according to the outdoor unit model. Use the
appropriate method to open the stop valves.
(1) Type A (Fig. 4-6)
1 Remove the cap, then turn one-quarter rotation counter-clockwise with a flat-bladed
screwdriver to complete open.
2 Check that the valves are fully open, then return the cap to its original state and
tighten it down.
(2) Type B (Fig. 4-6)
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.
(3) Type C (Fig. 4-7)
1 Remove the cap and turn the valve rod counterclockwise as far as it will go with
the use of a 4 mm 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.
A Valve
B Unit side
C Service port
D Handle
E Cap
F Completely closed
Refrigerant pipes are protectively wrapped
• The pipes can be protectively wrapped up to a diameter of ø90 before or after
connecting the pipes. Cut out the knockout in the pipe cover following the groove
and wrap the pipes.
Pipe inlet gap
• Use putty or sealant to seal the pipe inlet around the pipes so that no gaps remain.
(If the gaps are not closed, noise may be emitted or water and dust will enter the
unit and breakdown may result.)
2
G), wait five minutes, and make sure the
2 G), wait five minutes, and make sure the
2 G) and measure the surrounding tem-
G Completely open
H (On-side installation) Refrigerant piping side
I Direction the refrigerant flows in
J Wrench hole
K Operation section