23
Long pipe and high drop
1. Allowable pipe length and height difference
 
Permissible 
value
Piping part
Piping 
length
Total length of piping (actual length) 300m L1+L2+L3+L4+a+b+c+d+e
Longest piping L  Actual length 150m L1+L2+L3+L4+e
Piping length of indoor unit which is furthest to the rst branch 
piping L (*)
40m L2+L3+L4+e
Drop 
height  
Drop height between indoor and outdoor unit 
H
Up outdoor 50m  ——
Under outdoor 40m  ——
Drop height between indoor units h 15m  ——
Maximal length and drop height permissible of refrigerant piping
Drop height between indoor and outdoor units 
Drop height between 
indoor units 
h≤10m
Length of the longest piping after the 
rst branch piping L
First branch piping
Outdoor unit
Indoor unit
Length of the longest piping L
A. Outdoor unit
Unit pipe spec and connection method (unit: mm)
Model
Gas pipe side Liquid pipe side
Diameter (mm) Connecting method Diameter (mm) Connecting method
AU04 Ø15.88
Flared joint
Ø9.52
Flared jointAU05 Ø15.88 Ø9.52
AU06 Ø15.88 Ø9.52
Copper pipe selection:
Note: If the copper pipe with outer diameter 19.05 is coil pipe, the thickness should be over 1.1.
hardness Softness Half-hardness
Outer diameter (mm) Ø6.35 Ø9.52 Ø12.7 Ø15.88 Ø19.05 Ø22.22  Ø25.24  Ø28.58 
Min. thickness (mm) 0.8 0.8 1.0 1.0 1.0 1.1 1.2 1.4