Mitsubishi Electric CITY MULTI PUHY-HP72-240TNU-A Data Book page 111

13. OUTDOOR INSTALLATION
13-3-6. Twinning on the outdoor unit side
• The pipe from multiple outdoor units must be installed so that oil will not accumulate in the pipe under certain
conditions. Refer to the figures below for details.
* Small dots in the figures indicate branching points.
A To indoor units
(1) The pipe from the outdoor units must be inclined downward to the indoor unit side. In the figure on the right,
because the pipe is inclined upward, the oil in the pipe accumulates when Unit 1 is in operation and Unit 2 is
stopped.
Unit 1 Unit 2
A
(2) The distance between the unit bottom and the pipe (H) must be 0.2 m (7-7/8 in) or below. In the figure on the
right, because the distance is more than 0.2 m (7-7/8 in), the oil accumulates in Unit 1 when Unit 2 is in
operation and Unit 1 is stopped.
Unit 1 Unit 2
A
Unit 1 Unit 2
A
H
H ≤ 0.2 m (7-7/8 in)
(3) The vertical separation between units (H) must be 0.1 m (3-15/16 in) or below. In the figure on the right,
because the distance is more than 0.1 m (3-15/16 in), the oil accumulates in Unit 1 when Unit 2 is in operation
and Unit 1 is stopped.
Unit 2
Unit 1
A
H
H ≤ 0.1 m (3-15/16 in)
(4) The vertical separation between units (H) must be 0.1 m (3-15/16 in) or below. In the figure on the right,
because the distance is more than 0.1 m (3-15/16 in), the oil accumulates in Unit 2 when Unit 1 is in operation
and Unit 2 is stopped.
Unit 1
Unit 2
H
A
H ≤ 0.1 m (3-15/16 in)
• Make sure that the inclination tolerance of the Twinning pipe is ±15˚ to the ground to avoid unit damage.
A
• If the length of the pipe between the branching point and the outdoor unit exceeds 2 m (6 ft), provide a trap within
2 m (6 ft) from the branching point.
The trap must be at least 200 mm (7-7/8 in) in height. (gas pipe only) If there is no trap, oil can accumulate
inside the pipe, causing a shortage of oil and may damage the compressor.
* Small dots in the figures indicate branching points.
2 m (6 ft)
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.
• Refrigerant pipes may expand or shrink due to temperature fluctuations of the refrigerant inside the pipes. When installing long straight pipes,
provide traps to absorb the thermal expansions of the pipes.
MEES21K108
Unit 1
A
A
H
H > 0.2 m (7-7/8 in)
Unit 1
A
Unit 1
A
Twinning pipe
A
A
Unit 2
Unit 1 Unit 2
Unit 2
H
H > 0.1 m (3-15/16 in)
Unit 2
H
H > 0.1 m (3-15/16 in)
B
A
C
≤ 2 m (6 ft)
Hyper Heating Inverter Y-Series
To indoor units
A
Trap (gas pipe only)
B
Gas pipe
C
109