LG PREMTC00U Owners & Installation Manual page 250

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 of the
minimum combination ratio.
• the maximum number of indoor units for each Multi f / Multi f MaX heat pump systems is:
LMu187HV = 2 LMu247HV = 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: LMu369HV 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 166: Multi f outdoor unit Refrigerant Piping system Limitations.
Minimum Length for each
outdoor unit
Pipe (ft.)
LMu187HV 10
LMu247HV 10
LMu369HV 10
198 | DeSiGn & PracticeS
LMu369HV = 4
Max. 49 ft.
Maximum Piping Length to each indoor unit (ft.)
a B
82 82
82 82
82 82
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LMu540HV = 8
table 165: 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
ODU
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
IDU
IDU
Max 24.6 ft.
IDU
IDU
system (ft.)
164
246
246