50 | LIMITS / PLACEMENT
MUL
TI V S Three-Phase Outdoor Unit Engineering Manual
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THREE-PHASE
PIPING LIMITATIONS
• Always reference the LATS Multi V software re-
port.
• Connection piping from branch to branch cannot
exceed the main pipe diameter (A) used by the
outdoor unit.
• Install the Headers so that the pipe distances
between the between the connected indoor
units are minimized. Large differences in pipe
distances can cause indoor unit performances
to fluctuate.
• Indoor units must be installed at a lower position
than the Header.
•
Y-branches cannot be used after Headers.
Example: Seven (7) indoor units connected
Multi V S Three-Phase Outdoor Unit.
IDU: Indoor Units.
A: Main Pipe from Multi V S Three-Phase Outdoor
Unit to Y-branches.
B: Branch Piping.
C: Branch Piping to Indoor Unit (IDU).
ODU Capacity (ton)
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Liquid pipe (inches OD)
Vapor pipe (inches OD)
Liquid pipe (inches OD)
Vapor pipe (inches OD)
6.0
3/8Ø
3/4Ø
1/2Ø
7/8Ø
8.0
3/8Ø
7/8Ø
1/2Ø
1-1/8Ø
Downstream Total Capacity of IDUs (Btu/h)
1
Liquid pipe (inches OD)
Vapor pipe (inches OD)
1/4Ø
1/2Ø
3/8Ø
5/8Ø
3/8Ø
3/4Ø
3/8Ø
7/8Ø
Table 10: Main Pipe (A) Diameters from Multi V S Three-Phase to First Y-branch.
Table 11: Branch Pipe (B) Diameters from Y-branch to Y-branch / Header..
Vapor Pipe
Main Pipe
Liquid Pipe
Branch Piping
IDU
IDU
IDU
IDU
C
IDU
IDU
IDU
C
C
C
C
C
C
Multi V S Unit
A
B
Branch Piping
B
Header
Header
Branch Piping
B
Indoor Unit Capacity
1
Liquid pipe (inches OD)
Vapor pipe (inches OD)
1/4Ø
1/2Ø
3/8Ø
5/8Ø
3/8Ø
3/4Ø
3/8Ø
7/8Ø
Table 12: Indoor Unit Connecting Pipe from Branch (C).
1
9,600-24,200 Btu/h 4-way 3 feet x 3 feet Cassette and 15,400-24,200 Btu/h High Static Ducted indoor units have Ø3/8 (liquid) and Ø5/8 (vapor).
Example of Pipe Sizing
The following pages present Multi V S Three-Phase piping limitations and are for illustrative purposes only. Designers MUST use LATS when designing LG VRF systems.
Conditional Applications
Conditional applications are computed in LATS. See below for an explanation of when pipes are upsized.
If the equivalent length between the first Y-branch to the farthest indoor unit is >131 feet (up to 295 feet maximum):
•
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pipes. If the next size up is not available, or if the piping segment diameters are the same as main pipe (A) diameters, sizing up is not possible.
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