Part 3 - S
yst
em Design and Ins
talla
tion
Amazon Unitario Top Discharge
161
5.6 Branch Joints
Notes for installers
Use U-shaped branch joints as specified on the
construction drawings – do not replace U-shaped branch
joints with tee joints.
Indoor branch joints may be installed either horizontally
or vertically. Horizontal branch joints must be installed
at an angle to the horizontal not exceeding 10° in order
to avoid uneven distribution of refrigerant and possible
malfunction. Refer to Figure 3-5.8.
To ensure even distribution of refrigerant, a limitation
is placed on how close branch joints may be installed to
bends, other branch joints and the straight sections of
piping leading to indoor units. Refer to Part 3, 4.6 “Branch
Joints”.
Figure 3-5.8: Branch joint orientation
5.7 Pipe Flushing
5.7.1 Purpose
To remove dust, other particles and moisture, which could cause compressor malfunction if not flushed out before the
system is run, the refrigerant piping should be flushed using nitrogen. As described in Part 3, 5.1.1 “Installation procedure”,
pipe flushing should be performed once the piping connections have been completed with the exception of the final
connections to the indoor units. That is, flushing should be performed once the outdoor units have been connected but
before the indoor units are connected.
5.7.2 Procedure
Notes for installers
Warning
Only use nitrogen for flushing. Using carbon dioxide risks leaving condensation in the piping. Oxygen, air, refrigerant,
flammable gases and toxic gases must not be used for flushing. Use of such gases may result in fire or explosion.
Procedure
The liquid and gas sides can be flushed simultaneously; alternatively, one side can be flushed first and then Steps 1 to
8 repeated, for the other side. The flushing procedure is as follows:
1. Cover the inlets and outlets of the indoor units to prevent dirt getting blown in during pipe flushing. (Pipe flushing
should be carried out before connecting the indoor units to the piping system.)
2. Attach a pressure reducing valve to a nitrogen cylinder.
3. Connect the pressure reducing valve outlet to the inlet on the liquid (or gas) side of the outdoor unit.
4. Use blind plugs to block all liquid (gas) side openings, except for the opening at the indoor unit which is furthest
from the outdoor unit (“Indoor unit A” in Figure 3-5.9).
5. Start to open the nitrogen cylinder valve and gradually increase the pressure to 0.5MPa.
6.
Allow time for nitrogen to flow as far as the opening at indoor unit A.
7.
Flush the first opening:
a) Using suitable material, such as a bag or cloth, press firmly against the opening at indoor unit A.
b) When the pressure becomes too high to block with your hand, suddenly remove your hand allowing gas
to rush out.
c) Repeatedly flush in this manner until no further dirt or moisture is emitted from the piping. Use a clean
cloth to check for dirt or moisture being emitted. Seal the opening once it has been flushed.
8. Flush the other openings in the same manner, working in sequence from indoor unit A towards the outdoor unit.
Refer to Figure 3-5.10.
9. Once flushing is complete, seal all openings to prevent dust and moisture from entering.
Figure 3-5.9: Pipe flushing using nitrogen
Figure 3-5.10: Pipe flushing sequence
1
②
⑥
⑤
④
③
①
Notes:
1. 1-2-3-4-5-6 working towards the outdoor unit.
liquid pipe
gas pipe
Outdoor
unit
Indoor
unit A
Indoor
unit B
nitr
og
en g
as cylinder
