Multi F Outdoor Unit 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:
LMU187HV = 2 LMU247HV = 3 LMU369HV = 4 LMU540HV = 8
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 165: Equivalent Piping Length for Elbows, Y-branches, and
Branch Distribution Units.
Max. 49 ft.
Max 24.6 ft.
A
B
C
D
ODU
IDU
IDU
IDU
IDU
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.
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
LMU187HV 10 82 82 - - 164
LMU247HV 10 82 82 82 - 246
LMU369HV 10 82 82 82 82 246
1
Kit contains two Y-branches: one for liquid and one for vapor.
Table 166: 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, 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.
Using Refrigerant Components
The following are examples of manual pipe size calculations. Designers are highly encouraged to use LATS for Multi F systems.
Due to our policy of continuous product innovation, some specications may change without notication.
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198 | DESIGN & PRACTICES
Multi F and Multi F MAX Heat Pump System Engineering Manual
MULTI
F
MAX
MULTI
F