Pipe Installation; Brazing; Indoor Unit Pipe Connections; Opening The Knockout Hole - Fujitsu Airstage AOU72RLAVL Installation Manual

5. PIPE INSTALLATION

5.1. Brazing

If air or another type of refrigerant enters the refrigera-
tion cycle, the internal pressure in the refrigeration
cycle will become abnormally high and prevent the
unit from exerting its full performance.
Apply nitrogen gas while brazing the pipes.
Nitrogen gas pressure: 2.9 psi (0.02 MPa) (= pressure
felt sufficiently on the back of your hand)
If a pipe is brazed without applying nitrogen gas, it will create an oxidation film.
This can degrade performance or damage the parts in the unit (such as the compressor
or valves).
Do not use flux to braze pipes. If the flux is the chlorine type, it will cause the pipes to
corrode.
In addition, if the flux contains fluoride, it will affect the refrigerant piping system due to
deterioration of refrigerant oil.
For brazing material, use phosphor copper that does not require flux.

5.2. Indoor unit pipe connections

For details, refer to the Installation Instruction Sheet of each part.
Separation tube
A
:
Outdoor unit or Refrigerant
branch kit
A
B
:
Indoor unit or Refrigerant
± 15°
branch kit
PROHIBITED
Header
Gas pipe
C
Outdoor
GOOD
unit side
Horizontal line
Liquid pipe
D
Outdoor
unit side
GOOD
PROHIBITED
Do not connect a separation tube after a header.
Leave the distance 0.5 m or more for straight part to branch tube and header.
2 ft (0.5 m) or more
Main pipe
To indoor unit
2 ft (0.5 m) or more
Main pipe
To indoor unit
2 ft (0.5 m) or more
2 ft (0.5 m) or more
En-7
CAUTION
Pressure regulating valve
Cap
Nitrogen gas
Brazing area
CAUTION
Horizontal
A
B
Horizontal line
GOOD GOOD
Horizontal line
Horizontal line
β
1
H = 0 to 3/8 in
1
(0 to 10 mm)
α
(α : 0° to 1°)
C
View
1
1
H
β : -10° to 10°
1
1
Vertical line
H = 0 to 3/8 in
2
α
(α : 0° to 1°)
2
2
β
H
2
β : -10° to 10°
2
2
D
View
CAUTION
Separation tube
To indoor unit
Header
To indoor unit
Separation tube
To indoor unit
Header
To indoor unit

5.3. Opening the knockout hole

Be careful not to deform or scratch the panel while opening the knockout holes.
To protect the piping insulation after opening a knockout hole, remove any burrs from
the edge of the hole. It is recommended to apply rust prevention paint to the edge of the
hole.
• Pipes can be connected from 3 directions, front, lateral side and bottom. (Fig. A)
• When connecting at the bottom, remove the service panel and piping cover on the front
of the outdoor unit, and open the knockout hole provided at the bottom corner of the
piping outlet.
Fig. A
3-11/16
(94)
13/16 (21)
Vertical
B
or
B A
Front connection
• It can be installed as shown on "Fig. B" cutting out the 2 slits as indicated on "Fig. C".
(When cutting slits, use a steel saw.)
Fig. B
(0 to 10 mm)
Slit

5.4. Pipe connection

Do not use mineral oil on a flared part. Prevent mineral oil from getting into the system
as this would reduce the lifetime of the units.
While brazing the pipes, be sure to blow dry nitrogen gas through them.
The maximum lengths of this product are shown in the table. If the units are further
apart than this, correct operation cannot be guaranteed.
5.4.1 Bending pipes
To prevent breaking of the pipe, avoid sharp bends. Bend the pipe with a radius of
curvature of 4 in (100 mm) or more.
If the pipe is bent repeatedly at the same place, it will break.
• If pipes are shaped by hand, be careful not to collapse them.
• Do not bend the pipes at an angle of more than 90°.
• When pipes are repeatedly bent or stretched, the material will harden, making it difficult
to bend or stretch them any more.
• Do not bend or stretch the pipes more than 3 times.
CAUTION
Service panel
9/16 (14)
3-9/16 (90)
1/2 (12)
2-3/8 (60)
Lateral connection
Fig. C
Slit
CAUTION
CAUTION
Unit: in (mm)
3-5/8
(92)
13/16 (21)
Top view of
the base
Bottom connection
Bottom
connection