En-8
5.3.3. Pipe connection
CAUTION
Be sure to install the pipe against the port on the indoor unit and the outdoor unit
correctly. If the centering is improper, the flare nut cannot be tightened smoothly. If the
flare nut is forced to turn, the threads will be damaged.
Do not remove the flare nut from the outdoor unit pipe until immediately before
connecting the connection pipe.
After installing the piping, make sure that the connection pipes do not touch the
compressor or outer panel. If the pipes touch the compressor or outer panel, they will
vibrate and produce noise.
(1) Detach the caps and plugs from the pipes.
(2) Center the pipe against the port on the outdoor unit, and then turn the flare nut by
hand.
(3) Tighten the flare nut of the connection pipe at the outdoor unit valve connector.
3-way valve (Liquid)
3-way valve (Gas)
Flare nut
Connection pipe
(Liquid)
Flare nut
Connection pipe
(Gas)
(4) After tightening the flare nut by hand, use a torque wrench to fully tighten it.
CAUTION
Hold the torque wrench at its grip, keeping it in a right angle with the pipe, in order to
tighten the flare nut correctly.
• Outer panel may be distorted if fastened only with a wrench. Be sure to fix the
elementary part with a spanner and fasten with a wrench (refer to below diagram).
•
Do not apply force to the blank cap of the valve or hang a wrench, etc., on the cap. It
may cause leakage of refrigerant.
Blank cap
Flare nut
Torque wrench
Holding
wrench
Torque wrench
90°
Flare nut [in. (mm)]
Tightening torque [lbf·ft. (N·m)]
1/4 (6.35) dia.
11.8 to 13.3 (16 to 18)
3/8 (9.52) dia.
23.6 to 31.0 (32 to 42)
1/2 (12.70) dia.
36.1 to 45.0 (49 to 61)
5/8 (15.88) dia.
46.5 to 55.3 (63 to 75)
3/4 (19.05) dia.
66.4 to 81.1 (90 to 110)
5.3.4. Handling precautions for the valves
•
Mounted part of Blank cap is sealed for protection.
•
Fasten blank cap tightly after opening valves.
Table A
Blank cap [in. (mm)]
Tightening torque [lbf·ft (N·m)]
1/4 (6.35)
14.8 to 18.4 (20 to 25)
3/8 (9.52)
14.8 to 18.4 (20 to 25)
1/2 (12.70)
18.4 to 22.1 (25 to 30)
5/8 (15.88)
22.1 to 25.8 (30 to 35)
3/4 (19.05)
25.8 to 29.5 (35 to 40)
Operating the valves
• Use a hexagon wrench (size 4 mm).
• Opening
(1) Insert the hexagon wrench into the valve shaft, and turn it
counterclockwise.
(2) Stop turning when the valve shaft can no longer be turned.
(Open position)
• Closing
(1) Insert the hexagon wrench into the valve shaft, and turn it clockwise.
(2) Stop turning when the valve shaft can no longer be turned.
(Closed position)
Opening direction
Hexagon wrench
Seal (blank cap
installation portion)
Liquid pipe
Gas pipe
Opening direction
5.4. Sealing test
WARNING
Before operating the compressor, install the pipes and securely connect them.
Otherwise, if the pipes are not installed and if the valves are open when the compressor
operates, air could enter the refrigeration cycle. If this happens, the pressure in the
refrigeration cycle will become abnormally high and cause damage or injury.
After the installation, make sure there is no refrigerant leakage. If the refrigerant leaks
into the room and becomes exposed to a source of fire such as a fan heater, stove, or
burner, it produces a toxic gas.
Do not subject the pipes to strong shocks during the sealing test. It can rupture the
pipes and cause serious injury.
CAUTION
Do not block the walls and the ceiling until the sealing test and the charging of the
refrigerant gas have been completed.
•
After connecting the pipes, perform a sealing test.
•
Make sure that the 3-way valves are closed before performing a sealing test.
•
Pressurize nitrogen gas to 4.15 MPa to perform the sealing test.
•
Add nitrogen gas to both the liquid pipes and the gas pipes.
• Check all flare connections and welds. Then, check that the pressure has not
decreased.
•
Compare the pressures after pressurizing and letting it stand for 24 hours, and check
that the pressure has not decreased.
* When the outdoor air temperature changes 41°F (5°C), the test pressure changes
0.05 MPa. If the pressure has dropped, the pipe joints may be leaking.
•
If a leak is found, immediately repair it and perform the sealing test again.
•
After completing the sealing test, release the nitrogen gas from both valves.
•
Release the nitrogen gas slowly.
Pressure regulating valve
Pressure gauge
Nitrogen
Indoor unit
Outdoor unit
Vacuum pump
5.5. Vacuum process
CAUTION
Perform a refrigerant leakage test (air tightness test) to check for leaks using nitrogen
gas while all valves in the outdoor unit are closed. (Use the test pressure indicated on
the nameplate.)
Be sure to evacuate the refrigerant system using a vacuum pump.
The refrigerant pressure may sometimes not rise when a closed valve is opened after
the system is evacuated using a vacuum pump. This is caused by the closure of the
refrigerant system of the outdoor unit by the electronic expansion valve. This will not
affect the operation of the unit.
If the system is not evacuated sufficiently, its performance will drop.
Use a clean gauge manifold and charging hose that were designed specifically for use
with R410A. Using the same vacuum equipment for different refrigerants may damage
the vacuum pump or the unit.
Do not purge the air with refrigerants, but use a vacuum pump to evacuate the system.
(1) Check that the valves are closed by removing the blank caps from the gas and
liquid pipes.
(2) Remove the charging port cap, and connect the gauge manifold and the vacuum
pump to the charging valve with the service hoses.
(3) Vacuum the indoor unit and the connecting pipes until the pressure gauge indicates
–0.1 MPa (-1 bar).
(4) When –0.1 MPa (-1 bar) is reached, operate the vacuum pump for at least
60 minutes.
(5) Disconnect the service hoses and fit the charging port cap to the charging valve to
the specified torque. (Refer to the table on the next page)
(6) Remove the blank caps, and fully open the 3-way valves with a hexagon wrench
[Torque: 6 to 7 N·m (4 to 5 lbs·ft)].
(7) Tighten the blank caps of the 3-way valve to the specified torque. (Refer to Table A
on this page)
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