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4. Refrigerant Piping Installation

4.1 Length and Drop Height Requirements for the Piping

Connections to the Indoor and Outdoor Units

The length and drop height 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 tempera-
tures 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.

• 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.

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.

4.7 Vacuum

Create a vacuum in the system according to the instructions in the installation
manual of the outdoor unit.

4.8 Refrigerant

Charge the system with refrigerant according to the instructions in the
installation manual of the outdoor unit.

4.6 Heat Insulation Treatment for Gas-Liquid Piping 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 6) to carry out the insulation treatment,
and close all gaps.

Unit

body

Attached insulation

heat pump belt

On-site

piping side

Face upwards

Figure 4.5

Figure 4.1

Torque wrench
Pipe socket cap

Pipe fittings

Normal wrench



Slot the refrigerant piping into the brass nut (accessory 13), and expand the

pipe socket. Refer to the following table for the size of the pipe socket and
the appropriate tightening torque.

Figure 4.2

External diameter

(mm)

Tightening

torque

Figure 4.3

Apply refrigerant oil



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

•

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).

•

For the vacuum, make sure that the air and liquid cut-off valves of the
outdoor unit are all closed (maintain the factory status).

Caution

R0.4~0.8

45°± 2