20
4.3.2 Allowable length and height difference for refrigerant piping
The equivalent length of each elbow and U-shape branch joint is 0.5m, and the equivalent length of each branch
header is 1m.
Install the indoor units such that they are as equidistant as possible on both sides of the U-shape branch joint.
When the outdoor unit is above the indoor unit, and the level difference exceeds 20 m, it is recommended that an
oil return bend be set up at every 10 m interval on the gas pipe of the main piping. The recommended
specifications of the oil return bend are shown in Figure 4.8.
The allowable length of the farthest indoor unit to the first branch joint in the system should be equal to or less than
40m unless specified conditions are met, in which case the permitted length is up to 120m. Please refer to
requirement 2.
Special-purpose branch joints from the manufacturer should be used for all branch joints. Failing to do so may
lead to severe system malfunction.
NOTE
Figure 4.6
Piping diagram of V8 combinable series
Piping diagram of V8i individual series
Refer to the following table and figure (for reference only) to determine the appropriate size.
A
L
M
B
C
D
E
G
H
I
J
F
g3
g2
g1
G1
L1
L2
L3
L4
L5
L6
a
b
c
d
e
f
g
h
i
j
k
L7
L8
L9
L10
N1
N2
N3
N4
N5
N7
N8
N9
N10
N11
N6
W3 W2 W1
Equivalent length of piping between the farthest indoor unit and the first
outdoor branch joint≤260m.
Piping between the farthest indoor unit and the first indoor branch joint≤120m.
Largest level difference between indoor
unit and outdoor unit ≤110m
Largest level difference
between indoor units
h1≤40m.
Pipe
Branch
Indoor Unit
Figure 4.7
A
B
C
D
E
G
H
I
J
F
L1
L2
L3
L4
L5
L6
a
b
c
d
e
f
g
h
i
j
k
L7
L8
L9
L10
N1
N2
N3
N4
N5
N7
N8
N9
N10
N11
N6
W1
Equivalent length of piping between the farthest indoor unit and the first
outdoor branch joint≤260m.
Piping between the farthest indoor unit and the first indoor branch joint≤120m.
Largest level difference between indoor
unit and outdoor unit ≤110m
Largest level difference
between indoor units
h1≤40m.
Pipe
Branch
Indoor Unit
Pipe and Component NamesTable 4.2
Designation
G1, g1, g2, g3
L, M
L1
L2 to L10
A to J
a to k
Name DesignationName
Outdoor unit connection pipe
Outdoor unit branch joint
Main pipe
Indoor unit main pipe
Indoor unit branch joint
Indoor unit auxiliary connection pipe
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