Y-Branch Pipe Sizing When Installing A Triple-Frame System; Header Pipe Sizing When Installing A Single Outdoor Unit System - 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.

Y-branch Pipe Sizing When Installing a Triple-Frame System

Example: Five (5) indoor units connected
ODU: Outdoor Units.
IDU: Indoor Units.
A: Main Pipe from Outdoor Unit to Y-branch.
B: Y-branch to Y-branch.
C: Y-branch to Indoor Unit.
• 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 capac-
ity, and, where applicable, slave1 outdoor unit
capacity must be greater than or equal to the
slave2 outdoor unit capacity.

Header Pipe Sizing When Installing a Single Outdoor Unit System

Example: Six (6) indoor units connected
ODU: Outdoor Unit.
IDU: Indoor Units.
A: Main Pipe from Outdoor Unit to Header.
C: Header to Indoor Unit.
See pages 122-123 for refrigerant pipe diameter and pipe length tables.
REFRIGERANT PIPING DESIGN
Slave2 ODU
-
A
©
Piping Design Guideline Summary
Slave1 ODU
Master ODU
To
outdoor
units
A
Length: ≤492 feet (656 feet conditional application)
ℓ: ≤131 feet (295 feet conditional application)
B
Y-branch
C C
IDU
IDU
Elevation2: ≤131 feet
ODU
Length: ≤492 feet (656 feet conditional application)
Header
C
C C C
IDU
IDU
IDU
IDU
Elevation2: ≤131 feet
Y-branch
To indoor units
B B C
C C
IDU IDU
IDU
ℓ: ≤131 feet (295 feet
conditional application)
Brazed Cap
C
C
IDU
IDU
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