C. Connection with VRF indoor units and AHUs
Fig. 4-5. Permitted refrigerant piping lengths and level differences (C)
Table 4-15. Piping and Component Names
L6
L7
j
k
n
m
VRF DX AHU control box 2
VRF DX AHU control box 1
M
L
G1
L1
L5
L2
A
C
B
L3
L4
N3
c
b
a
N2
N1
MS
N11
N9
MS
l
N10
MS
h
N8
MS
d
e
f
g
i
N5
N6
N7
Header
N4
MS box
Header branch
Indoor unit
LEGEND
Branch joint
g2
g1
g3
First branch
OUTDOOR UNITS
(One or more outdoor units)
(Slave 1) (Master)
(Slave 2)
Y#\#***
Maximum piping length from the first branch joint to
$#+
Y#\**$$
Maximum level difference between Indoor
#`
NAME
Outdoor unit connection pipe
Outdoor unit branch joint
Main pipe
Indoor unit main pipe
Branch joint between main pipe and MS box
Indoor unit auxiliary pipe
VRF indoor unit
AHU
Designation
g1, g2, g3, G1
L, M
L1
L2 to L7
A to C
a to n
N1 to N8, N10
N9, N11
Table 4-16. Summary of permitted refrigerant piping lengths and level differences
Permitted values
{`
+
`
+
Piping in Fig. 4-5
\ { #
Piping lengths
Level
dif
ferences
Total piping length
1
Piping between farthest VRF
indoor unit or AHU and outdoor
unit or the last multi-outdoor
piping branch
2
Actual length
Equivalent length
Outdoor unit is above
4
Outdoor unit is below
5
Piping between outdoor unit and outdoor branch joint
Largest level difference between
VRF indoor unit or AHU and
outdoor unit
L1 + L2 + L4 + f + i
L2 + L4 + f + i
Piping between farthest VRF indoor unit or AHU and first
branch joint
3
Largest level difference between VRF indoor units or
AHUs
Notes:
1. The total length of piping in one refrigerant system should not exceed 1000 m. When calculating the total length of piping,
the actual length of the indoor main pipes (the piping between the first indoor branch joint and MS box, L2 to L7) should be
doubled.
2. The piping between the farthest VRF indoor unit (N8) or AHU (N11) and outdoor unit or the last multi-outdoor piping branch
joint (L) should not exceed 175 m (actual length) and 200 m (equivalent length). (The equivalent length of each branch joint is
0.5 m). When the equivalent piping length from outdoor units to the farthest VRF indoor unit or AHU]_*$
the main pipe (L1) should be increased as Table 4-12.
14
