18 | Piping installation
Installer and user reference guide
77
RXMLQ8 + RXYLQ10~14T7Y1B*
VRV IV system air conditioner
4P543427-1A – 2020.10
b It is necessary to increase the pipe size of the gas and liquid piping if the pipe
length between the first branch kit and the farthest indoor unit is over 40m.
If the increased pipe size is larger than the pipe size of the main pipe, then
the pipe size of the main pipe has to be increased as well.
Increase the pipe size as follows:
9.5 → 12.7; 12.7 → 15.9; 15.9 → 19.1; 19.1 → 22.2; 22.2 → 25.4
(a)
; 28.6 →
31.8
(a)
; 34.9 → 38.1
(a)
(a) If the size-up size is NOT available, you must use the standard size. Sizes
bigger than the size-up size are NOT allowed. But even if you use the
standard size, you can increase the maximum allowable length after the first
branch if all other conditions are met.
Example: unit8: b+c+d+e+f+g+p≤90m and b+c+d+e+f+g>40m; increase the
pipe size of b, c, d, e, f, g.
c When the piping size is increased (stepb), the piping length has to be
counted as double (except for the main pipe and the pipes that are not
increased in pipe size).
The total piping length has to be within limitations (see table above).
Example: a+b×2+c×2+d×2+e×2+f×2+g×2+h+i+j+k+l+m+n+p≤1000m (500m).
d The piping length difference between the nearest indoor unit (from first
branch) to the outdoor unit and the farthest indoor unit to the outdoor unit
is ≤40m.
Example: The farthest indoor unit 8. The nearest indoor unit 1 → (a+b+c+d+e
+f+g+p)–(a+h)≤40m.
18.1.7 Piping length: VRV DX and Hydrobox
For system containing VRVDX indoor units and Hydrobox:
System setup
Example Description
Example 1
a
A
h i j k l m n
B C D E F G
p
b c d e f
1 2 3 4 5 6 7
8
g
H1
H2
Branch with refnet joint
Example 2
a
b
c d e f
i
k
j
g h
A B
1 2 3 4 5 6
7 8
H1
H2
Branch with refnet joint
and refnet header
Example 3
a
c
b d e f
i
g h
1 2 3 4 5 6 7
8
H1
H2
Branch with refnet header
1~7 VRVDX indoor units
8 Hydrobox unit (HXY080/125)
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