LG MULTI V 5 Engineering Manual page 92

PIPING LIMITATIONS
For Systems Designed for Heat Recovery Operation
Following pages present Multi V 5 piping limitations and are for illustrative purposes only. Designers MUST use LATS when designing LG VRF systems.
Example of Pipe Sizing When Installing a Heat Recovery System
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.
• Always reference the LATS Multi V software
report.
• Larger-capacity outdoor units must be the master
in a multi-frame system.
• Master outdoor unit capacity must be greater
than or equal to the slave1 outdoor unit capac-
ity, and, where applicable, slave1 outdoor unit
capacity must be greater than or equal to the
slave2 outdoor unit capacity.
• 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 between the connected indoor units are mini-
mized. Large differences in pipe distances can cause indoor unit performances to fluctuate.
• Y-branches and other header branches cannot be installed downstream of the initial header branch.
•
• If large capacity indoor units (>12,000 Btu/h with piping sizes >5/8Ø / 3/8Ø) are installed, the valve group setting must be used. (Refer to
the PCB of the heat recovery unit for the valve group control setting.)
Table 25: Main Pipe (A) Diameters 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
14-16 5/8Ø
18-20 5/8Ø
22-28 3/4Ø
30-42 3/4Ø
92 | LIMITS / PLACEMENT
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.
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
1-3/8Ø
1-3/8Ø
1-5/8Ø
©
Slave2
ODU
Slave1
ODU
Master ODU
A
Y-branch (first)
Closest
IDU
C
IDU
B
C
B
HRU
C
IDU
Case 1
B
C
B
HRU
IDU
C
C
IDU
IDU
Liquid Pipe
(inches OD)
5/8Ø 1/2Ø
3/4Ø 1/2Ø
3/4Ø 5/8Ø
7/8Ø 5/8Ø
7/8Ø 3/4Ø
1-1/8Ø 3/4Ø
1-1/8Ø 7/8Ø
1-1/8Ø 7/8Ø
Y-branch
To
Outdoor Unit
Y-branch (second)
HRU
B
C
C
HRU
IDU
B
Case 2
Header
x
C
IDU
C
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
To Indoor Units
*
C
Brazed
cap
C
Farthest
IDU
IDU
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase
No Increase