Refrigerant Piping Installation; Air Tightness Test - mundoclima MVD DC2 Manual De Instalación Y Usuario

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 8), and expand the

pipe socket. Refer to the following table for the size of the pipe socket and
the appropriate tightening torque.
Normal wrench
Torque wrench
Pipe socket cap
Outer diameter of
connecting piping (mm)
Φ6.4
Φ9.5
Φ12.7
Φ15.9
Φ19.1
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.
Do not let air, dust, and other particles invade the piping system during the
installation of the connecting pipes.
Install the connecting pips only when the indoor and outdoor units are
secured.
Make sure to keep the connecting pipes dry during installation so that no
water will enter the piping system.
Before the socket cap is installed on the pipe socket, apply some

refrigerant oil on the socket (both inside and outside), then rotate it three
or four times before you tighten the cap. See Figure 4.2.
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 4.3.
Figure 4.3

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).
22
Tightening torque (N.m)
14.2~17.2
32.7~39.9
49.5~60.3
61.8~75.4
97.2~118.6
Apply refrigerant oil
Figure 4.2
1 Copper piping
2 Section being brazed
3 Nitrogen connection
4 Hand valve
5 Pressure-reducing valve
6 Nitrogen