Mitsubishi Electric CITY MULTI PURY-P-YNW-A2 Installation Manual page 22

・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.
・Support the on-site pipes near the outdoor unit at 0.5-meter intervals or less, and at 2-meter intervals or less in
other areas. Support the pipes so that the bending part is securely fixed in place.
・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 expansion of the pipes.
・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.
Ⓐ To a BC controller
(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
Ⓐ
(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
Ⓐ
Unit 1 Unit 2
Ⓐ
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 Unit 1
Ⓐ
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 1
Unit 2
H
Ⓐ
H ≤ 0.1 m (3-15/16 in)
・The Twinning Kit must be installed horizontally using a level vessel to avoid unit damage.
Ⓑ
Ⓐ
WT09973X01
Unit 1 Unit 2
Ⓐ
Unit 1 Unit 2
Ⓐ
H
H > 0.2 m (7-7/8 in)
Unit 2
Unit 1
Ⓐ
H
H > 0.1 m (3-15/16 in)
Unit 1
Unit 2
Ⓐ
H
H > 0.1 m (3-15/16 in)
Twinning Kit
Ⓐ
Ⓑ Level vessel
21