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MUL
TI V Split Rooftop Unit Installation Manual
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Proper system operation depends on the installer using utmost care while assembling the piping system. The following pages are an over-
view of best practices when installing the refrigerant piping system.
Refrigerant Pipe Length Limits
Table 6: Piping Outer Diameter (O.D.) size.
ODU Capacity
Ton (kBtu/h)
Liquid pipe (O.D.) Low Pressure pipe (O.D.) High Pressure pipe (O.D.)
10 (119.7)
1/2 in
1-1/8 in
3/4 in
12 (144)
7/8 in
14 (168)
5/8 in
16-18 (192-206)
1-1/8 in
20 (233.1)
1-3/8 in
22-28 (264-336)
3/8 in
30-42 (360-504)
1-3/8 in
One of the most critical elements of a Multi V system is the refrigerant piping. The table below lists pipe length limits that must be followed in
the design of a Multi V refrigerant pipe system:
Table 7: Multi V Refrigerant Piping System Limitations.
Pipe Length
(ELF = Equivalent Length
of pipe in Feet)
Longest total equivalent piping length
3,280 feet
Longest distance from outdoor unit to RTU
656 feet (Actual) 738 feet (Equivalent)
Distance between fittings and RTU
≥20 inches
Distance between fittings and Y-branches
≥20 inches
Distance between two Y-branches
≥20 inches
Minimum distance between RTU to any Y-branch
3 feet from RTU to Y-branch
Maximum distance between first Y-branch to farthest RTU
131 feet (295 feet for conditional applications)
Elevation
(All Elevation Limitations
are Measured in Actual
Feet)
If outdoor unit is above or below RTU
164 feet
Between RTUs
98 feet
Table 8: Equivalent Piping Length for Y-branches, Headers, and Other Piping Components.
Component
Size (Inches)
Long Radius Elbow (ft.)
1/4
3/8
1/2
5/8
3/4
7/8
1
1-1/8 1-1/4 1-3/8 1-1/2 1-5/8
1-3/4
2-1/8
Y-branch (ft.)
1
0.5
0.6
0.7
0.8
1.2
1.3
1.5
1.6
1.8
2.0
2.1
2.3
2.5
2.8
1
Kit contains two Y-branches: one for liquid and one for vapor.
REFRIGERANT PIPING
Selection of Pipe Sizes
For piping work, follow the maximum tolerated length, difference in height, and length after a branch. Determine the proper size referring to
following tables and reference figure (only for indication)