Mitsubishi Electric Y Série Manuel D'installation page 9

Precautions for outdoor unit combinations
Refer to [Fig. 9.2.2] for the positioning of twinning pipes.
[Fig. 9.2.2]
<A> Make sure the pipes from the twinning pipe to the outdoor unit are sloped downwards (towards the twinning pipes).
A
F
<B> When the piping on the outdoor unit side (from the twinning pipe) exceeds 2 m [6 ft], ensure a trap (gas pipe only) within 2 m [6 ft].
Make sure the height of the trap is 200 mm [7-7/8 in] or more.
If there is no trap, oil can accumulate inside the pipe, causing a shortage of oil and may damage the compressor.
F
2 [ 6 ]
Caution:
• Do not install traps other than the ones between outdoor units described on a separate sheet to prevent oil backflow and compressor start-up failure.
• Do not install solenoid valves to prevent oil backflow and compressor start-up failure.
• Do not install a sight glass because it may show improper refrigerant flow.
If a sight glass is installed, inexperienced technicians that use the glass may overcharge the refrigerant.
<C> Slope of twinning pipes
Make sure the slope of the twinning pipes are at an angle within ±15˚ to the ground.
If the slope exceeds the specified angle, the unit may be damaged.
G
<D> Pipe connection example
H
A B
Downward slope
F G
Twinning pipe
I J
Twinning Kit
C
C
F
I
H
J
C
Upward slope 1st branch
Slope of the twinning pipes are at an angle within ±15˚ to the ground
Straight run of pipe that is 500 mm [19-11/16 in] or more
C
B
F
D
F
C
E
D E
Trap (gas pipe only) Within 2 m [6 ft]
H
Pipes on site
(Unit: m [ft])
9