Pipe Connection - Mitsubishi Electric MCFH-A24WV Installation Manual

6-3

PIPE CONNECTION

1. Indoor unit connection
• Connect both liquid and gas piping to the indoor unit.
- Apply a thin coat of refrigerant oil on the seat surface
of pipe.
- For connection first align the center, then hand tighten
the first 3 to 4 turns of flare nut.
- Use tightening torque table below as a guideline for
the indoor unit side union joint section, and tighten us-
ing two wrenches. Excess tightening damages the
flared section.
Pipe diameter Tightening torque
mm N·m kgf·cm
6.35 13.7 to 17.7 140 to 180
15.88 73.5 to 78.4 750 to 800
2. Outdoor unit connection
• Connect pipes to stop valve pipe joint of the outdoor unit in
the same manner applied for the indoor unit.
- For tightening, use a torque wrench or spanner, and
use the same tightening torque applied for the indoor
unit.
3. Refrigerant pipe insulation
• Use pipe cover (foam polyethylene 8 mm thickness) which
is contained in accessories, insulate both liquid and gas
pipes together. Put the refrigerant piping and apply piping
tape C.
a Indoor unit refrigerant pipe
b Flare joint
d Pipe cover
A Refrigerant pipe
C Piping tape
Connecting wire and
refrigerant pipes
must be separated.
4. Knockout cover
• Attach knockout cover 9 to close knockout hole to prevent
rat or something strange from getting into the indoor unit.
9 Knockout cover
0 Screw for 9 4 × 10 mm
6-4
• Use the vacuum pump for air purging for the purpose of environmental protection.
Connect the refrigerant pipes (both liquid pipe and the gas pipe) between the indoor and the outdoor unit.
Remove the service port cap of the stop valve on the side of the outdoor unit gas pipe. (The stop valve will
not work in it initial state fresh out of the factory (totally closed with cap on).)
Connect the gauge manifold valve and the vacuum pump to the service port of the stop valve on the gas
pipe side of the outdoor unit.
Check the vacuum with the gauge manifold valve, then close the gauge manifold valve, and stop the vacuum
pump.
Leave as it is for one or two minutes. Make sure the pointer gauge manifold valve remains in the same
position. Confirm that the pressure gauge shows–0.101 Mpa [Gauge] (–760 mmHg).
a
b
c
A
After refrigerant pipes are connected and evacuated, fully open all stop valves on both sides of gas pipe and
c
liquid pipe.
Operating without fully opening lowers the performance and this causes trouble.
d
0
9
Cap for service port
Cap for stop valve
11
PURGING PROCEDURES · LEAK TEST
PURGING PROCEDURES
Run the vacuum pump. (Vacuumize for more than 15 minutes.)
*Close
Stop valve
*Open
Hexagonal wrench
*4 to 5 turns
Remove the gauge manifold valve quickly from the service port of the stop valve.
Pipe length up to 7 m
No gas charge is needed.
Tighten the cap to the service port to obtain the initial status.
Retighten the cap.
Leak test
Tightening torque
N·m kgf·cm
13.7 to 17.7 140 to 180
19.6 to 29.4 200 to 300
Compound pressure
-0.101MPa
Stop valve
gauge (for R410A)
(-760 mmHg)
Pressure gauge
(for R410A)
Gauge manifold
valve (for R410A)
Handle High
Handle
Low Charge hose
Stop (for R410A)
valve
Vacuum (or the vacuum pump with
Service port
pump
the function to prevent the
Window
back flow)
Charge hose
Adapter for preventing the
(for R410A)
back flow
Pipe length exceeding 7 m
Charge the prescribed amount of
gas. (refer to 3)