APPLICATION |   55
Application Guidelines
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REFRIGERANT PIPING DESIGN
Design Guideline Summary
Device Connection Limitations
A single-zone system consists of one outdoor unit and one indoor 
unit. One of the most critical elements of a single-zone system is 
the refrigerant piping. If the connection piping is not within allowable 
limits, there will be reliability, performance, noise, and vibration 
issues. Table 29 below lists pipe length limits that must be followed 
in the design of a Single Zone High Efficiency Wall Mount refrigerant 
pipe system, and Table 30 includes additional refrigerant charge 
necessary for longer piping lengths. Refer to the figure for maximum 
length and elevation of piping.
Table 29: Single Zone High Efciency Refrigerant Piping System Limitations.
Figure 33: Single Zone High Efciency Wall Mount System Layout.
Model Numbers
LS090HSV5
(LSN090HSV5/
LSU090HSV5)
LS120HSV5
(LSN120HSV5/
LSU120HSV5)
LS180HSV5
(LSN180HSV5/
LSU180HSV5)
Pipe Sizes
Vapor
Ø3/8 Ø3/8 Ø5/8
Liquid
Ø1/4 Ø1/4 Ø3/8
Pipe Length
(ELF = Equivalent Length of 
pipe in Feet)
Standard Piping Length
24.6 24.6 24.6
Piping Length with No 
Additional Refrigerant
41 41 24.6
Longest total equivalent
piping length
82 82 114.8
Shortest total equivalent
piping length
9.8 9.8 9.8
Distance between fittings 
and indoor units or outdoor
units
≥20 inches ≥20 inches ≥20 inches
Elevation  
(All Elevation Limitations are 
Measured in Actual Feet)
If outdoor unit is above 
indoor unit
49.2 49.2 49.2
If outdoor unit is below
indoor unit
49.2 49.2 49.2
Additional Refrigerant Needed (oz/ft)
0.22 0.22 0.38
Outdoor Unit
Indoor Unit
A
B
Outdoor Unit
Indoor Unit
A
B
Model Numbers  
Refrigerant Piping Length (ft.)
16.4 24.6 32.8 41.0 49.2  65.6 82.0  98.4 114.8 131.2 147.6  164.0 
LS090HSV5
(LSN090HSV5 / LSU090HSV5)
Additional
Refrigerant
Charge (oz.)
0 0 0 0 1.8 5.4 9.0 - - - - -
LS120HSV5
(LSN120HSV5 / LSU120HSV5)
0 0 0 0 1.8 5.4 9.0 - - - - -
LS180HSV5
(LSN180HSV5 / LSU180HSV5)
0 0 3.1 6.2 9.3 15.6 21.8 28.0 34.3 - - -
Table 30: Single Zone High Efciency Refrigerant Piping System Additional Refrigerant Charge.
• Capacity is based on standard length.
• Equivalent Pipe Length = Actual Pipe Length + Number of Bends x 0.3.
• Additional Refrigerant Charge Calculation : X (g) = [ (Refrigerant Pipe Length) - (No Charge Pipe Length) ] × (Additional Refrigerant).
• There is no need to add refrigerant if equivalent pipe is less than the “piping length with no additional refrigerant” in the table above.