En-5
4.3.2. Pipe connection
• The gas and liquid pipes connections must be brazed.
• Be sure to braze them before performing any wiring work or installing the drain pipe.
Outer diameter of pipe
Connection Pipe (Liquid) 1/2 in (12.7 mm)
Connection Pipe (Gas) 7/8 in (22.22 mm)
Control box
Rear panel
Thermistor
Maintenance panel
Connection Pipe (Liquid)
Safety drain pan
Pipe heat insulation
& Pipe rubber
Connection Pipe (Gas)
WARNING
Be sure to use wet cloth, etc., to protect the pipe rubber, pipe heat insulation, heat
exchanger thermistor, and the heat insulation of the safety drain pan as shown below.
Because these parts are extremely fl ammable, they can cause a fi re if they are not
properly protected.
In case the heat exchanger thermistor may be damaged by heat of brazing, which
lead to failure of normal operation. (AR96 only)
The heat exchanger contains a thermistor.
Completely cover the pipe
rubber and pipe heat insulation
with wet cloth, etc., to prevent
them from burning.
Pipe heat insulation
Pipe rubber
Pipe rubber
Pipe heat insulation
Brazing
Do not expose the
thermistor to the fl ame.
Protect these areas with wet cloth, etc.
Do not expose the unit (control box, rear panel, maintenance panel, etc.) and the inlet
grille to the fl ame. The exposure of these parts to the fl ame will adversely affect their
appearance and functions or cause a fi re.
CAUTION
If air or another type of refrigerant enters the refrigeration cycle, the internal pressure
in the refrigeration cycle will become abnormally high and prevent the unit from
exerting its full performance.
Apply nitrogen gas while
brazing the pipes. Nitrogen
gas pressure:
2.9 psi (0.02 MPa) (= pressure
felt suffi ciently on the back of
your hand)
Pressure regulating valve
Cap
Nitrogen gas
Brazing area
If a pipe is brazed without applying nitrogen gas, it will create an oxidation fi lm.
This can degrade performance or damage the parts in the unit (such as the
compressor or valves).
Do not use fl ux to braze pipes. If the fl ux is the chlorine type, it will cause the pipes to
corrode. Furthermore, if the fl ux contains fl uoride, it will adversely affect the refrigerant
pipe system such as by degrading the refrigerant oil.
For brazing material, use phosphor copper that does not require fl ux.
4. PIPE INSTALLATION
CAUTION
Be more careful that foreign matter (oil, water, etc.) does not enter the piping than with
refrigerant R410A models. Also, when storing the piping, securely seal the openings
by pinching, taping, etc.
While welding the pipes, be sure to blow dry nitrogen gas through them.
4.1. Selecting the pipe material
CAUTION
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 0.04 oz./100 ft. (40 mg/10 m).
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 (R22) 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 [in (mm)] Thickness [in (mm)] Material
1/4 (6.35) 0.032 (0.80)
COPPER
JIS H3300 C1220T-O
or equivalent
3/8 (9.52) 0.032 (0.80)
1/2 (12.70) 0.032 (0.80)
5/8 (15.88) 0.039 (1.00)
3/4 (19.05) 0.047 (1.20)
7/8 (22.22) 0.039 (1.00)
COPPER
JIS H3300 C1220T-H
or equivalent
4.2. 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 (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 heat insulation around the refrigerant piping. If the
expected humidity level is 70 to 80 %, use heat insulation that is 9/16 in (15 mm)
or thicker and if the expected humidity exceeds 80 %, use heat insulation that is
13/16 in (20 mm) or thicker. If heat insulation is used that is not as thick as specifi ed,
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 (20 °C)).
4.3. Brazing connection (pipe connection)
4.3.1. 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 diffi cult
to bend or stretch them any more. Do not bend or stretch the pipes more than 3 times.
CAUTION
To prevent breaking of the pipe, avoid sharp bends.
If the pipe is bent repeatedly at the same place, it will break.
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