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7. PIPE INSTALLATION
Be careful that foreign matter (oil, water, etc.) does not enter
the piping with refrigerant R410A 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.
7.1. Selecting the pipe material
Do not use existing pipes.
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 (33 ft).
Do not use copper pipes that have a collapsed, deformed,
or discolored portion (especially 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 R410A incurs pressure higher than when
using conventional refrigerant, it is necessary to choose
adequate materials.
•
Thicknesses of copper pipes used with R410A are as
shown in the table.
•
Never use copper pipes thinner than those indicated in the
table even if they are available on the market.
Thicknesses of Annealed Copper Pipes (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)
En-12
CAUTION
CAUTION
Thickness [mm (in.)]
0.80 (0.032)
0.80 (0.032)
0.80 (0.032)
1.00 (0.039)
1.20 (0.047)
7.2. Pipe requirement
CAUTION
Refer to the Installation Manual of the outdoor unit for
description of the length of connecting pipe or for difference
of its elevation.
• Use pipe with water-resistant heat insulation.
CAUTION
Install heat insulation around both the gas and liquid pipes.
Failure to do so may cause water leaks.
Use heat insulation with heat resistance above 248°F.
(Reverse cycle model only)
In addition, if the humidity level at the installation location
of the refrigerant piping is expected to exceed 70 %,
install heat insulation around the refrigerant piping. If the
expected humidity level is 70-80 %, use heat insulation
that is 15mm(19/32 in.) or thicker and if the expected
h u m i d i t y e x c e e d s 8 0 % , u s e h e a t i n s u l a t i o n t h a t i s
20mm(25/32 in.) or thicker. If heat insulation is used
that is not as thick as specified, condensation may form
on the surface of the insulation. In addition, use heat
insulation with heat conductivity of 0.045 W/(m·K) or less
(at 68°F).
7.3. Flare connection (Pipe connection)
WARNING
Tighten the flare nuts with a torque wrench using the
specified tightening method. Otherwise, the flare nuts could
break after a prolonged period, causing refrigerant to leak
and generate a hazardous gas if the refrigerant comes into
contact with a flame.
7.3.1. Flaring
• Use special pipe cutter and flare tool exclusive for 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 respectively) onto the pipe
and perform the flare processing with a flare tool. Use
the special R410A flare tool, or the conventional flare
tool. Leakage of refrigerant may result if other flare nuts
are used.
Protect the pipes by pinching them or with tape to
(4)
prevent dust, dirt, or water from entering the pipes.
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