LG Multi V ARUN053GF2 Installation Manual page 29

The following is an example of manual pipe size calculations. Designers are highly encouraged to use LATS instead of manual calculations.
system using y-branches and Header
Example: Five (5) indoor units connected
Space II Unit.
IDU: Indoor Units.
Y-branches.
Header.
A: Main Pipe from First Y-branch.
B: Pipe from Y-branch to Y-branch or Header.
C: Pipe from Y-branch or Header to Indoor Unit.
D: Pipe to Farthest Indoor Unit.
• Indoor units should be installed at a lower
position than the Header.
• Y-branch pipes cannot be used after
Headers.
• Install the Header so that the pipe dis-
tances between the between the con-
nected indoor units are minimized. Large
differences in pipe distances can cause in-
door unit performances to fluctuate.
• Always reference the LATS Multi V software
report.
Table 18: Pipe Capabilities.
Length
A + ΣB + ΣC + D ≤475.7 feet
ℓ
Elevation1
Elevation2
Distance between fittings and indoor units
Distance between fittings and Y-Branches / Headers
Distance between two Y-Branches / Headers
For calculation purposes, assume equivalent pipe length of Y-branch is 1.6 feet, and equivalent pipe length of header is 3.3 feet.
1
Table 17: Refrigerant Pipe Diameter (B) from Y-branch to Y-branch / Header.
Downstream Total Capacity of IDUs (Btu/h)
≤19,100
<54,600
≤76,400
• Connection piping from branch to branch cannot exceed the main pipe diameter (A) used by the Space II unit.
• Y-branches and other header branches cannot be installed downstream of the initial header branch.
refrIGerant PIPInG connectIons
Total pipe length
Elevation differential (Space II unit ↔ Indoor unit)
Elevation differential (Indoor unit ↔ Indoor unit)
Liquid Pipe (Inches O.D.)
Ø1/4
Ø3/8
Ø3/8
Due to our policy of continuous product innovation, some specifications may change without notification.
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Refrigerant Piping System Examples
Space Unit
To Space
Unit
First
Y-Branch
Second
Y-Branch
Longest actual pipe length
A + B + D ≤230 feet
Longest pipe length after first branch
B + D ≤ 131 feet
≤ 98.4 feet
≤ 49 feet
Vapor Pipe (Inches O.D.)
Ø1/2
Ø5/8
Ø3/4
Y-branch
To Indoor
Units
Header
IDU IDU
Length ≤ 230 feet
ℓ 131 feet
≤
IDU
IDU
Equivalent pipe length
≤295 feet
≥20 inches
≥20 inches
≥20 inches
Brazed Cap
IDU
1
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