Main Pipe Diameter From Outdoor Unit To First Y-Branch - LG Multi IV Engineering Manual

The following is an example of manual pipe size calculations. Designers are highly encouraged to use LATS instead of manual calculations.
Pipe Sizing for ARUB Series Heat Recovery Systems
Example: Triple-frame system, four (4) heat recovery units,
one (1) header, and twelve (12) indoor units connected
ODU: Outdoor Units.
HRU: Heat Recovery Units.
IDU: Indoor units.
A: Main Pipe from Outdoor Unit to First Y-branch.
B: Heat Recovery Unit to Heat Recovery Unit, Y-branch to Heat
Recovery Unit, Heat Recovery Unit to Header, or Y-branch to Y-branch.
C: Heat Recovery Unit / Header to Indoor Unit.
• Connection piping from branch to branch cannot exceed the main
pipe diameter (A) used by the outdoor unit.
• Install the header branches or heat recovery units so that the pipe
distances between the connected indoor units are minimized.
Large differences in pipe distances can cause indoor unit perfor-
• Y-branches and other headers branches cannot be installed down-
stream of the initial header branch.
• Total capacity of indoor units in series connection of heat
• If large capacity indoor units (>12,000 Btu/h with piping sizes
>5/8Ø / 3/8Ø) are installed, the valve group setting should be used.
(Refer to the PCB of the heat recovery unit for the valve group
control setting.)
• Always reference the LATS Multi V software report.
See pages 125-126 for refrigerant pipe diameter and pipe length
tables.
Table 39: Main Pipe (A) Diameter from Outdoor Unit to First Y-branch.
ODU
Capacity
Liquid Pipe
(ton)
(inches OD)
6 3/8Ø
8 3/8Ø
10 1/2Ø
12 1/2Ø
12-14* 5/8Ø
14-16 5/8Ø
18-20 5/8Ø
22-28 3/4Ø
30-42 3/4Ø
*ARUB145BTE4 / ARUB145DTE4 and ARUB169BTE4 / ARUB169DTE4 only.
Standard Pipe Diameter
Low Pressure Vapor High Pressure Vapor
Pipe (inches OD) Pipe (inches OD)
3/4Ø
7/8Ø
1-1/8Ø
1-1/8Ø
1-1/8Ø
1-1/8Ø
1-3/8Ø
1-3/8Ø
1-5/8Ø
©
REFRIGERANT PIPING DESIGN
Piping Design Guideline Summary
Slave2
ODU
Slave1
ODU
Closest
IDU
C
IDU
C
HRU
C
IDU
Case 1
C
IDU
Case 1: Maximum height is 131 feet if installed with a Y-branch.
Case 2: Maximum height is 16 feet in heat recovery control unit series connection.
• Larger-capacity outdoor units must be the master in a multi-frame
system.
• Single-compressor outdoor units (72,000 Btu/h capacity) cannot be the
master outdoor unit in a multi-frame system.
• Master outdoor unit capacity must be greater than or equal to the
slave1 outdoor unit capacity, and, where applicable, slave1 outdoor unit
capacity must be greater than or equal to the slave2 outdoor unit
capacity.
Liquid Pipe
(inches OD)
5/8Ø 1/2Ø
3/4Ø 1/2Ø
3/4Ø 5/8Ø
7/8Ø 5/8Ø
7/8Ø 3/4Ø
7/8Ø 3/4Ø
1-1/8Ø 3/4Ø
1-1/8Ø 7/8Ø
1-1/8Ø 7/8Ø
Master ODU
A
Y-branch (first)
Y-branch
To
B
outdoor unit
B
Y-branch (second)
B
HRU
B
B
C
C
HRU
HRU IDU
B
Case 2
Header
C
C
C IDU
C
IDU
IDU
IDU
IDU
Low Pressure Vapor High Pressure Vapor
Pipe (inches OD) Pipe (inches OD)
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
To indoor units
*
C
Brazed
cap
x
C
Farthest
IDU
IDU
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
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