LG MULTI F Series Engineering Manual page 360

REFRIGERANT PIPING DESIGN
Design Guideline Summary
The following are examples of manual pipe size calculations. Designers are highly encouraged to use LATS for Multi F systems.
Device Connection Limitations
• The minimum number of connected and operating indoor units to Multi F / Multi F MAX systems is two, taking into consideration the
minimum combination ratio.
• The maximum number of indoor units for each Multi F / Multi F MAX heat pump systems is:
LMU18CHV = 2 LMU24CHV = 3
One of the most critical elements of multi-zone systems is the refrigerant piping. The following pages list pipe length limits that must be
followed in the design of Multi F and Multi F MAX refrigerant pipe systems:
Using Refrigerant Components
Field-supplied elbows are allowed as long as they are designed for
use with R410A refrigerant. The designer, however, should be cau-
tious with the quantity and size of fittings used, and must account for
the additional pressure losses in equivalent pipe length calculation
for each branch. The equivalent pipe length of each elbow must be
added to each pipe segment.
Multi F System
Example: LMU36CHV outdoor unit with four (4)
indoor units connected.
ODU: Outdoor Unit.
IDU: Indoor Unit.
A, B, C, D: Pipes from Outdoor Unit to Indoor Unit.
Table 328:Multi F Outdoor Unit Refrigerant Piping System Limitations.
Minimum Length for Each
Outdoor Unit
Pipe (ft.)
LMU18CHV 10
LMU24CHV 10
LMU36CHV 10
360 | DESIGN & PRACTICES
LMU36CHV = 4
Max. 49.2 feet
Maximum Piping Length to Each Indoor Unit (ft.)
A B
82 82
82 82
82 82
Due to our policy of continuous product innovation, some specifications may change without notification.
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LMU540HV = 8
Table 327:Equivalent Piping Length for Elbows, Y-branches, and Branch
Distribution Units.
Component
Elbow (ft.)
Y-Branch Kit (ft., Multi F MAX systems
only)
1
Branch Distribution Unit (ft., Multi F
MAX systems only)
Kit contains two Y-branches: one for liquid and one for vapor.
1
A
B
C
D
Maximum Total Piping Length for Each
C D
- -
82 -
82 82
F
MULTI
F
MULTI MAX
Size (Inches)
1/4 3/8 1/2 5/8 3/4
0.5 0.6 0.7 0.8 1.2
1.6
8.2
Max. 24.6 feet
System (ft.)
164
246.1
246.1