5 Preparation
Installer and user reference guide
13
RXYSQ6T7Y1B9
VRV IV-S system air conditioner
4P404677-1A – 2016.03
Indoor unit capacity
index
Piping outer diameter size (mm)
Gas pipe
Liquid pipe
<150
15.9
9.5
150≤x≤176
19.1
Example:
Downstream capacity for B-1 = capacity index of unit 3-1
+ capacity index of unit 3-2
C: Piping between refrigerant branch kit and
indoor unit
Use the same diameters as the connections (liquid, gas) on the
indoor units. The diameters of the indoor units are as follows:
Indoor unit capacity
index
Piping outer diameter size (mm)
Gas pipe
Liquid pipe
15~50
12.7
6.4
63~140
15.9
9.5
5.3.4
To select refrigerant branch kits
For piping example, refer to
"5.3.3 To select the piping size" on
Refnet joint at first branch (counting from outdoor unit)
When using refnet joints at the first branch counted from the outdoor
unit side, choose from the following table in accordance with the
capacity of the outdoor unit.
Example:
Refnet joint A→B‑1.
Outdoor unit capacity type
(HP)
Refrigerant branch kit
6
KHRQ22M20T
Refnet joints at other branches
For refnet joints other than the first branch, select the proper branch
kit model based on the total capacity index of all indoor units
connected after the refrigerant branch.
Example:
Refnet joint
B‑1→C‑1.
Indoor unit capacity index
Refrigerant branch kit
<176
KHRQ22M20T
Refnet headers
Concerning refnet headers, choose from the following table in
accordance with the total capacity of all the indoor units connected
below the refnet header.
Indoor unit capacity index
Refrigerant branch kit
<176
KHRQ22M29H
INFORMATION
Maximum 8 branches can be connected to a header.
5.3.5
Refrigerant piping length and height difference
The piping lengths and height differences must comply with the following requirements.
Requirement
Limit (VRV DX indoor units)
Maximum actual piping length
▪ Example 1.1, unit 8: a+b+c+d+e+f+g+p≤Limit
▪ Example 1.2, unit 6: a+b+h≤Limit
▪ Example 1.2, unit 8: a+i+k≤Limit
▪ Example 1.3, unit 8: a+i≤Limit
120 m
Maximum equivalent piping length
(a)
150 m
Maximum total piping length
▪ Example 1.1: a+b+c+d+e+f+g+h+i+j+k+l+m+n+p≤Limit
300 m
Maximum length first branch kit-indoor unit
▪ Example 1.1, unit 8: b+c+d+e+f+g+p≤Limit
▪ Example 1.2, unit 6: b+h≤Limit
▪ Example 1.2, unit 8: i+k≤Limit
▪ Example 1.3, unit 8: i≤Limit
40 m
Maximum height difference outdoor-indoor
Outdoor higher than indoor
▪ Examples: H1≤Limit
50 m
Outdoor lower than indoor
40 m
Maximum height difference indoor-indoor
▪ Examples: H2≤Limit
15 m
(a)
Assume equivalent piping length of refnet joint=0.5 m and refnet header=1 m (for calculation purposes of equivalent piping length, not for
refrigerant charge calculations).
Example 1 (VRV DX indoor units)
Example 1.1
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
