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4. Refrigerant Piping Installation
4.1 Length and Level Difference Requirements for the Piping
Connections to the Indoor and Outdoor Units
The length and level difference requirements for the refrigerant piping are
different for different indoor and outdoor units. Refer to the installation manual
of the outdoor unit.
4.2 Piping Material and Size
1. Piping material: Copper pipes for air handling.
2. Piping size: Choose and purchase copper pipes that correspond to the
length and size calculated for the selected model in the installation manual
of the outdoor unit and your actual project requirements.
4.3 Piping Layout
1. Seal the two ends of the piping properly before you connect the indoor and
outdoor piping. Once unsealed, connect the piping of the indoor and outdoor
units as quickly as possible to prevent dust or other debris from entering the
piping system via the unsealed ends, as this may cause the system to
malfunction.
2. If the piping needs to go through walls, drill the opening in the wall, and place
accessories like casings and covers for the opening properly.
3. Place the refrigerant connecting piping and the communication wiring for the
indoor and outdoor units together, and bundle them tightly to make sure air
does not enter and condensate to form water that may leak from the system.
4. Insert the bundled piping and wiring from outside the room through the wall
opening into the room. Be careful when you lay out the piping. Do not
damage the piping.
4.4 Piping Installation
Refer to the installation manual attached with the outdoor unit on installation
of the refrigerant piping for the outdoor unit.
All gas and liquid piping must be properly insulated; otherwise, this may
cause water to leak. Use heat insulation materials that can withstand high
temperatures above 120°C to insulate the gas pipes. In addition, the
insulation of the refrigerant piping should be reinforced (20 mm or thicker) in
situations where there is high temperature and/or high humidity (when part
of refrigerant piping part is higher than 30°C or when the humidity exceeds
RH80%). Otherwise, the surface of the heat insulation material may be
exposed.
Before the works are carried out, verify that the refrigerant is R410A. If the
wrong refrigerant is used, the unit may malfunction.
Other than the specified refrigerant, do not let air or other gases enter the
refrigeration circuit.
If the refrigerant leaks during installation, make sure you fully ventilate the
room.
Use two wrenches when you install or dismantle the piping, a common
wrench and a torque wrench. See Figure 4.1.
Pipe fittings
Figure 4.1
Slot the refrigerant piping into the brass nut (accessory), and expand the
pipe socket. Refer to the following table for the size of the pipe socket and
the appropriate tightening torque.
External
Tightening torque
diameter (mm)
Φ6.35
14.2-17.2N·m
Φ9.53
32.7-39.9N·m
Φ12.7
49.5-60.3N·m
Φ15.9
61.8-75.4N·m
Φ19.1
97.2-118.6N·m
Caution
• Apply the appropriate tightening torque according to the installation
conditions. Excessive torque will damage the socket cap, and the cap will
not be tight if you apply insufficient torque, leading to leakages.
Normal wrench
Torque wrench
Pipe socket cap
Flared opening
Flared opening
diameter (A)
8.3-8.7mm
90°± 4
12-12.4mm
A
45°± 2
15.4-15.8mm
R0.4~0.8
18.6-19mm
Figure 4.2
22.9-23.3mm
Before the socket cap is installed on the pipe socket, apply some refrigerant
oil on the socket (both inside and outside), and then rotate it three or four
times before you tighten the cap. See Figure 4.3.
Precautions to take when welding the refrigerant pipes
• Before you weld the refrigerant pipes, fill the pipes with nitrogen first to discharge the
air in the pipes. If no nitrogen is filled during welding, a large amount of oxide film will
form inside the piping which may cause the air conditioning system to malfunction.
• Welding can be carried out on the refrigerant pipes when the nitrogen gas has been
replaced or refilled.
• When the pipe is filled with nitrogen during welding, the nitrogen must be reduced to
0.02 MPa using the pressure release valve. See Figure 4.4.
Figure 4.4
4.5 Air Tightness Test
Carry out the air tightness test on the system according to the instructions in the
installation manual of the outdoor unit.
Caution
• The Air Tightness Test helps to ensure that the air and liquid cut-off
valves of the outdoor unit are all closed (maintain the factory defaults).
4.6 Heat
Insulation
Connections for the Indoor Unit
The heat insulation treatment is carried out on the piping at the gas and
liquid sides of the indoor unit respectively.
a. The piping on the gas side must use heat insulation material that can
withstand temperatures of 120°C and more.
b. For the piping connections of the indoor unit, use the insulation casing for
copper pipes (accessory) to carry out the insulation treatment, and close
all gaps.
Unit
body
4.7 Vacuum
Create a vacuum in the system according to the instructions in the installation
manual of the outdoor unit.
Caution
•
For the vacuum, make sure that the air and liquid cut-off valves of the
outdoor unit are all closed (maintain the factory status).
4.8 Refrigerant
Charge the system with refrigerant according to the instructions in the
installation manual of the outdoor unit.
28
Apply refrigerant oil
Figure 4.3
1
Copper piping
2
Section being brazed
3
Nitrogen connection
4
Hand valve
5
Pressure-reducing valve
6
Nitrogen
Treatment
for
Gas-Liquid
Face upwards
On-site piping
side
Attached insulation
heat pump belt
Figure 4.5
Piping
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