3. 5. Pipe installation
• During installation, make sure that the refrigerant pipe is attached ﬁ rmly before you
run the compressor.
• Do not operate the compressor under the condition of refrigerant piping not attached
properly with 2-way or 3-way valve open. This may cause abnormal pressure in the
refrigeration cycle that leads to breakage and even injury.
• During the pump-down operation, make sure that the compressor is turned off
before you remove the refrigerant piping.
• Do not remove the connection pipe while the compressor is in operation with 2-way
or 3-way valve open. This may cause abnormal pressure in the refrigeration cycle
that leads to breakage and even injury.
• When installing and relocating the air conditioner, do not mix gases other than the
speciﬁ ed refrigerant R410A or R32 to enter the refrigerant cycle.
• If air or other gas enters the refrigerant cycle, the pressure inside the cycle will rise
to an abnormally high value and cause breakage, injury, etc.
• If refrigerant leaks while work is being carried out, ventilate the area. If the
refrigerant comes in contact with a ﬂ ame, it produces a toxic gas.
• Be more careful so that foreign matter (oil, water, etc.) does not enter the piping
than with refrigerant R410A or R32 models. Also, when storing the piping, securely
seal the openings by pinching, taping, etc.
• While brazing the pipes, be sure to purge with dry nitrogen gas.
3.5.1. Pipe connection
Use special pipe cutter and ﬂ are tool designed for R410A or R32 pipework.
(1) Cut the connection pipe to the necessary length with a pipe cutter.
(2) Hold the pipe downward so that cuttings will not enter the pipe and remove any burrs.
(3) Insert the ﬂ are nut (always use the ﬂ are nut attached to the indoor unit(s) and outdoor
unit or branch box respectively) onto the pipe and perform the ﬂ are processing with a
ﬂ are tool. Use the special R410A or R32 ﬂ are tool, or the conventional ﬂ are tool. Leak-
age of refrigerant may result if other ﬂ are nuts are used.
(4) Protect the pipes by pinching them or with tape to prevent dust, dirt, or water from
entering the pipes.
Dimension A [mm]
Pipe outside diameter
Flare tool for R32, clutch
When using conventional ﬂ are tools to ﬂ are R32 pipes, the dimension A should be approxi-
mately 0.5 mm more than indicated in the table (for ﬂ aring with R32 ﬂ are tools) to achieve
the speciﬁ ed ﬂ aring. Use a thickness gauge to measure the dimension A.
Pipe outside diameter [mm
NOTES: The ﬂ are nut speciﬁ cation is compliant with ISO14903.
Check if [L] is ﬂ ared uniformly
and is not cracked or scratched.
0 to 0.5
Width across ﬂ ats of
Flare nut [mm]
■ Bending pipes
• If pipes are shaped by hand, be careful not to collapse them.
• Do not bend the pipes at an angle more than 90°.
• When pipes are repeatedly bend or stretched, the material will harden, making it difﬁ cult
to bend or stretch them any more.
• Do not bend or stretch the pipes more than 3 times.
• To prevent breaking of the pipe, avoid sharp bends.
• If the pipe is bent repeatedly at the same place, it will break.
■ Flare connection
• Be sure to connect the pipe against the port on the indoor unit and the outdoor unit
correctly. If the centering is improper, the ﬂ are nut cannot tightened smoothly. If the
ﬂ are nut is forced to turn, the threads will be damaged.
• Do not remove the ﬂ are nut from the indoor unit pipe until immediately before
connecting the connection pipe.
• Do not use mineral oil on ﬂ ared part. Prevent mineral oil from getting into the system
as this would reduce the lifetime of the units.
(1) Detach the caps and plugs from the pipes.
(2) Center the pipe against the port on the indoor unit, and then turn the ﬂ are nut by hand.
(3) When the ﬂ are nut is tightened properly by your hand, hold the body side coupling with
a separate spanner, then tighten with a torque wrench. (See the table below for the
ﬂ are nut tightening torques.
• Hold the torque wrench at its grip, keeping it in the right angle with the pipe, in order to
tighten the ﬂ are nut correctly.
• Tighten the ﬂ are nuts with a torque wrench using the speciﬁ ed tightening method.
Otherwise, the ﬂ are nuts could break after a prolonged period, causing refrigerant to
leak and generate a hazardous gas if the refrigerant comes into contact with a ﬂ ame.
Indoor unit pipe
Flare nut [mm (in.)]
6.35 (1/4) dia.
9.52 (3/8) dia.
12.70 (1/2) dia.
15.88 (5/8) dia.
19.05 (3/4) dia.
Connection pipe (Gas)
Tighten with 2 wrenches.
Tightening torque [N·m (kgf·cm)]
16 to 18 (160 to 180)
32 to 42 (320 to 420)
49 to 61 (490 to 610)
63 to 75 (630 to 750)
90 to 110 (900 to 1,100)