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9
Application Information
Refrigerant Piping
Piping Length and Elevation
When the pipe length becomes too long, both the capacity and reliability drop. As the number of bends increases,
system piping resistance to the refrigerant
fl
ow increases, thus lowering the cooling capacity, and as the result
the compressor may become defective. Always choose the shortest path and follow the recommendation as
tabulated below:
Outdoor Unit
Indoor Unit
L
E
Model
Indoor (FTXN/FTK)
25
35
50
60
Outdoor (RXN/RK)
25
35
50
60
Min. Allowable Length (L), m
3
3
Max. Allowable Length (L), m
20
30
Max. Allowable Elevation (E), m
10
10
Gas Pipe Size, mm/(in)
9.52 (3/8")
12.70 (1/2")
15.88 (5/8")
Liquid Pipe Size, mm/(in)
6.35 (1/4")
6.35 (1/4")
Additional Charge
• The refrigerant gas is charged in the outdoor unit and, if the piping length is 7.5m, additional charge of the
refrigerant after vacuuming is not necessary.
• When the piping length is more than 7.5m, additional refrigerant charge (g) per additional 1m length as
tabulated:
Model
Indoor (FTXN/FTK)
25
35
50
60
Outdoor (RXN/RK)
25
35
50
60
Additional charge [g/m]
20
20
20
20
Example:
FTXN25 & RXN25 with 12m piping length, additional piping length is 4.5m.
Thus, Additional charge = 4.5[m] x 20[g/m]
= 90.0[g]