LMCN078HV Engineering Manual

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:
REFRIGERANT PIPING DESIGN
Design Guideline Summary
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:
Table 115:Equivalent Piping Length for Elbows, Y-branches, and Branch
Distribution Units.
Max. 49.2 feet
Max. 24.6 feet
A
B
C
D
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.
1
Kit contains two Y-branches: one for liquid and one for vapor.
Table 116:Multi F Outdoor Unit Refrigerant Piping System Limitations.
Component
Size (Inches)
1/4 3/8 1/2 5/8 3/4
Elbow (ft.)
0.5 0.6 0.7 0.8 1.2
Y-Branch Kit (ft., Multi F MAX systems
only)
1
1.6
Branch Distribution Unit (ft., Multi F
MAX systems only)
8.2
Field-supplied elbows are allowed as long as they are designed for
use with R410A refrigerant. The designer, however, must 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.
Using Refrigerant Components
The following are examples of manual pipe size calculations. Designers are highly encouraged to use LATS for Multi F systems.
LMU18CHV = 2 LMU24CHV = 3 LMU30CHV = 4 LMU36CHV = 4 LMU480HV = 8 LMU540HV = 8 LMU600HV = 8
Outdoor Unit
Minimum Length for Each
Pipe (ft.)
Maximum Piping Length to Each Indoor Unit (ft.)
Maximum Total Piping Length for Each
System (ft.)
A B C D
LMU18CHV 10 82 82 - - 164
LMU24CHV 10 82 82 82 - 246.1
LMU30CHV 10 82 82 82 82 246.1
LMU36CHV 10 82 82 82 82 246.1
LMU180HHV = 2 LMU240HHV = 3 LMU300HHV = 4 LMU360HHV = 5 LMU420HHV = 6
Due to our policy of continuous product innovation, some specications may change without notication.
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200 | DESIGN & PRACTICES
Multi F and Multi F MAX Indoor Unit Engineering Manual
MULTI
F
MAX
MULTI
F