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9
Refrigerant piping and vacuuming
WARNING
•
Ventilate the room if a refrigerant gas is leaking during the installation work.
If the leaking refrigerant gas comes in contact with fire, a toxic gas is generated.
•
After installation, confirm that no refrigerant gas is leaking.
If the leaking refrigerant gas comes in contact with fire from a fan heater, a stove, or a gas range, a toxic gas is
generated.
NOTE
When the refrigerant pipe is long, provide support brackets at intervals of 2.5 - 3 m to clamp the refrigerant pipe.
Otherwise, abnormal sound may be generated.
Use the flare nut attached with the indoor unit or R410A flare nut.
Permissible piping length and height difference
They vary depending on the outdoor unit.
For details, refer to the Installation Manual attached to the outdoor unit.
About the pipe material and size
Refrigerant piping at the liquid / gas side
Flaring
1
Cut the pipe with a pipe cutter.
Remove burrs completely.
Remaining burrs may cause gas leakage.
2
Insert a flare nut into the pipe, and flare the pipe.
As the flaring sizes of R410A differ from those of refrigerant R22, the flare tools newly
manufactured for R410A are recommended.
However, the conventional tools can be used by adjusting projection margin of the copper pipe.
Projection margin in flaring: B (Unit: mm)
Rigid (Clutch type)
Pipe material
Seamless phosphorous-deoxidized copper pipe
Model name
MMD-
VNK502HEX1E
VN502HEX1E
VNK802HEX1E
VN802HEX1E
VNK1002HEX1E(2)
VN1002HEX1E(2)
Pipe size
(mm)
Gas side
Ø9.5
Ø12.7
Ø12.7
Liquid side
Ø6.4
Ø6.4
Ø6.4
Outer dia. of copper pipe
R410A tool used
Conventional tool used
6.4, 9.5
0 to 0.5
1.0 to 1.5
12.7
B
Flaring dia. meter size: A (Unit: mm)
• The pressure of gas in the unit is the same as the atmospheric pressure. Therefore, no air leaking sound comes
out when the flare nut is loosened. This is not anything unusual.
• Use 2 wrenches to perform piping of indoor units.
• Refer to the table below for tightening torque.
•
Tightening torque of flare pipe connections
Pressure of R410A is higher than that of R22.
(Approx. 1.6 times) Therefore, using a torque wrench, tighten the flare pipe connecting sections which connect
the indoor and outdoor units of the specified tightening torque.
Incorrect connections may cause not only a gas leak, but also a trouble of the refrigeration cycle.
REQUIREMENT
Tightening with an excessive torque may crack the nut depending on installation conditions.
Tighten the nut within the specified tightening torque.
Leak check test and vacuuming
Refer to the Installation Manual of the outdoor unit for leak check test, vacuuming, adding a refrigerant, or checking
gas leakage.
REQUIREMENT
Do not turn on the indoor unit before leak check test and vacuuming are finished; otherwise, the electric expansion valve
is closed fully and vacuuming from the liquid or gas side is not performed properly. If the indoor unit should be turned
on, perform vacuuming from both the liquid side and the gas side.
Opening the valve fully
Open the valves of the designated outdoor unit fully.
Outer dia. of copper
pipe
A
+0
–0.4
* In case of flaring for R410A with the
conventional flare tool, pull it out approx.
0.5 mm more than that for R22 to adjust to
the specified flare size.
The copper pipe gauge is useful for
adjusting projection margin size.
R410A
6.4
9.1
9.5
13.2
12.7
16.6
Outer diameter of
connecting pipe (mm)
Tightening torque
(N•m)
Ø6.4
14 to 18 (1.4 to 1.8 kgf•m)
Ø9.5
34 to 42 (3.4 to 4.2 kgf•m)
Ø12.7
49 to 61 (4.9 to 6.1 kgf•m)
A
Using 2 wrenches
121-EN
122-EN
+00EH99887601-2_01EN.book Page 61 Thursday, September 15, 2016 5:23 PM
