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4. PIPE INSTALLATION
Be more careful that foreign matter (oil, water, etc.) does not enter the piping than with
refrigerant R32/R410A models. Also, when storing the piping, securely seal the open-
ings by pinching, taping, etc.
While welding the pipes, be sure to blow dry nitrogen gas through them.
4.1. Selecting the pipe material
Do not use existing pipes from another refrigeration system or refrigerant.
Use pipes that have clean external and internal sides without any contamination which
may cause trouble during use, such as sulfur, oxide, dust, cutting waste, oil, or water.
It is necessary to use seamless copper pipes.
Material: Phosphor deoxidized seamless copper pipes.
It is desirable that the amount of residual oil is less than 40 mg/10 m.
Do not use copper pipes that have a collapsed, deformed, or discolored portion (es-
pecially on the interior surface). Otherwise, the expansion valve or capillary tube may
become blocked with contaminants.
Improper pipe selection will degrade performance. As an air conditioner using R32/
R410A incurs pressure higher than when using conventional (R22) refrigerant, it is
necessary to choose adequate materials.
• Thicknesses of copper pipes used with R32/R410A are as shown in the table.
• Never use copper pipes thinner than those indicated in the table even if they are avail-
able on the market.
Thicknesses of Annealed Copper Pipes (R32/R410A)
Pipe outside diameter [mm (in)]
6.35 (1/4)
9.52 (3/8)
12.70 (1/2)
15.88 (5/8)
19.05 (3/4)
4.2. Pipe requirement
Refer to the installation manual for the outdoor unit for description of allowable pipe
length and height difference.
Use pipe with water-resistant thermal insulation.
Install thermal insulation around both the gas and liquid pipes. Failure to do so may
cause water leaks.
Use thermal insulation with heat resistance above 120 °C. (Reverse cycle model only)
In addition, if the humidity level at the installation location of the refrigerant piping is
expected to exceed 70 %, install thermal insulation around the refrigerant piping.
If the expected humidity level is 70 to 80 %, use thermal insulation that is 15 mm or
thicker and if the expected humidity exceeds 80 %, use thermal insulation that is 20 mm
or thicker. If thermal insulation is used that is not as thick as specified, condensation
may form on the surface of the insulation.
In addition, use thermal insulation with heat conductivity of 0.045 W/(m·K) or less
(at 20 °C).
4.3. Flare connection (pipe connection)
Tighten the flare nuts with a torque wrench using the specified tightening method. Oth-
erwise, the flare nuts could break after a prolonged period, causing refrigerant to leak
and generate hazardous gas if the refrigerant comes into contact with a flame.
4.3.1 Flaring
Use special flare tool exclusive for R32/R410A.
(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 flare nut (always use the flare nut attached to the indoor and outdoor units
(or RB unit) respectively) onto the pipe and perform the flare processing with a flare
tool. Use the special R32/R410A flare tool. Leakage of refrigerant may result if other
flare nuts are used.
(4) Protect the pipes by pinching them or with tape to prevent dust, dirt, or water from
entering the pipes.
CAUTION
CAUTION
Thickness [mm]
0.80
0.80
0.80
1.00
1.20
CAUTION
CAUTION
WARNING
Check if [L] is flared uniformly
and is not cracked or scratched.
Dimension A [mm]
Pipe outside diameter
Flare tool for R32/R410A,
[mm (in)]
clutch type
6.35 (1/4)
9.52 (3/8)
12.70 (1/2)
15.88 (5/8)
19.05 (3/4)
When using conventional (R22) flare tools to flare R32/R410A pipes, the dimension A
should be approximately 0.5 mm more than indicated in the table (for flaring with R32/
R410A flare tools) to achieve the specified flaring. Use a thickness gauge to measure the
dimension A. It is recommended that a R32/R410A flaring tool is used.
NOTE:
The fl are nut specifi cation is compliant with ISO14903.
Width across flats Pipe outside diameter [mm (in)] Width across flats of Flare nut [mm]
6.35 (1/4)
9.52 (3/8)
12.70 (1/2)
15.88 (5/8)
19.05 (3/4)
4.3.2 Bending pipes
• The pipes are shaped by your hands or pipe bender. Be careful not to collapse them.
• Do not bend the pipes in an angle more than 90°.
• When pipes are repeatedly bend or stretched, the material will harden, making it difficult
to bend or stretch them anymore. 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.
4.3.3 Pipe connection
When the flare nut is tightened properly by your hand, hold the body side coupling with a
separate spanner, then tighten with a torque wrench.
Be sure to install the pipe against the port on the indoor unit and the outdoor unit cor-
rectly. If the centering is improper, the flare nut cannot tightened smoothly. If the flare
nut is forced to turn, the threads will be damaged.
Do not remove the flare nut from the indoor unit pipe until immediately before connect-
ing the connection pipe.
Do not use mineral oil on flared part. Prevent mineral oil from getting into the system as
this would reduce the lifetime of the units.
Hold the torque wrench at its grip, keeping it at a right angle with the pipe, in order to
tighten the flare nut correctly.
Flare nut
Tightening torque
[mm (in)]
[N·m (kgf·cm)]
6.35 (1/4) dia.
16 to 18 (160 to 180)
9.52 (3/8) dia.
32 to 42 (320 to 420)
12.70 (1/2) dia.
49 to 61 (490 to 610)
15.88 (5/8) dia.
63 to 75 (630 to 750)
19.05 (3/4) dia.
90 to 110 (900 to 1,100)
Die
Pipe
Dimension B
0
-0.4
9.1
13.2
0 to 0.5
16.6
19.7
24.0
17
22
26
29
36
CAUTION
CAUTION
Tighten with 2 wrenches.
Holding
wrench
Flare
Torque
nut
wrench
Indoor unit pipe
Connection pipe
(Body side)
[mm]
En-6
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