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■ Cut the indoor side pipe of the RB unit with a pipe cutter.
Liquid pipe : φ6.35(1/4") → φ9.52(3/8")
Gas pipe
: φ12.7(1/2") → φ15.88(5/8")
Connection area
Cutting point (Center
of connection area)
NOTE: Insert the connection pipe fi rmly until it touches the RB unit pipe.
• Use a pipe cutter to cut a pipe. When removing burrs after pipe cutting, make sure
that loose particles do not get into the pipe.
6.2. Selecting the pipe material
Copper pipes
It is necessary to use seamless copper pipes and it is desirable that the amount of
residual oil is less than 40 mg/10 m. Do not use copper pipes having a collapsed, de-
formed or discolored portion (especially on the interior surface). Otherwise, the expan-
sion valve or capillary tube may become blocked with contaminants.
As an air conditioner using R410A incurs pressure higher than when using conventional
refrigerant (R22), 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 that in the table even when it is available on the market.
Thicknesses of Annealed Copper Pipes (R410A)
Pipe outside diam-
Thickness
eter [mm (in)]
[mm] *1
ø6.35 (1/4")
ø9.52 (3/8")
ø12.70 (1/2")
ø15.88 (5/8")
ø19.05 (3/4")
ø22.22 (7/8")
ø28.58 (1-1/8")
ø34.92 (1-3/8")
*1) Endurance pressure of the pipes 4.2MPa
6.3. Pipe connection
6.3.1. Brazing
If air or different type of refrigerant enters the refrigeration cycle, the internal pres-
sure 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: 0.02 MPa
(= suffi cient pressure to be felt on
the back of your hand or more)
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 com-
pressor 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.
In addition, if the fl ux contains fl uoride, it will affect the refrigerant piping system due to
deterioration of refrigerant oil.
For brazing material, use phosphor copper that does not require fl ux.
Connect
Connection pipe
CAUTION
Material
0.80
COPPER JIS H3300
0.80
C1220T-O or equivalent
0.80
(Allowable tensile
1.00
2
stress ≥ 33 (N/mm
))
1.20
COPPER JIS H3300
1.00
C1220T-H or equivalent
1.00
(Allowable tensile
1.20
2
stress ≥ 61 (N/mm
))
CAUTION
Pressure regulating valve
Cap
Nitrogen gas
Brazing area
6.3.2. Bending pipes
The pipes are shaped by your hands. Be careful not to collapse them. Do not bend the
pipes in an angle more than 90°.
When pipes are repeatedly bent 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. Bend the pipe with a radius of
curvature of 100 mm or over.
If the pipe is bent repeatedly at the same place, it will break.
6.3.3. Pipe connection
The pipe can be connected by brazing
Suction gas pipe
Liquid pipe
Discharge gas pipe
Brazing
6.4. Installing heat insulation
Insulate the suction gas pipe, discharge gas pipe, liquid pipe, and gas pipe with heat
insulation.
Use heat insulation with heat resistance above 120 °C.
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 15 mm or thicker and if
the expected humidity exceeds 80%, use heat insulation that is 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, at 20 °C, use heat insulation with heat
conductivity of 0.045 W/(m·K) or less.
6.4.1. Piping insulation
(1) After the sealing test is complete, carry out insulation work.
(2) Insulate all pipes and piping connection parts so that there is no gap in it.
(3) Firmly connect the terminal part (a) so that no air comes in or out.
(4) Do not squeeze the cable ties excessively so as to ensure that the insulation mate-
rial is thick.
(a)
RB Unit
Cable tie (locally purchased)
• Wind the coupler heat insulation (accessories) around the strainer section of the
discharge gas piping.
6.4.2. Installing cabinet insulation
If the relative humidity of the area may rise above 80%, install cabinet insulation (acces-
sories) in the following location:
Cabinet insulation
Install cabinet insulation under the
suction gas pipe on the connection
side of the outdoor unit.
CAUTION
Gas pipe
RB
unit
Liquid pipe
Brazing
CAUTION
Insulation (locally purchased)
(Unit: mm)
0 to 5
Align the center of the cabinet insulation
with the suction gas pipe axis.
En-6
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