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9.4 System piping (length) limitations
9.4.1 Piping length restrictions
Make sure to perform the piping installation within the range of the
maximum allowable pipe length, allowable level difference and
allowable length after branching as indicated below. The pattern
will be discussed, including VRV indoor units combined with
RA indoor units.
Definitions
Actual piping length: pipe length between outdoor
(1)
and indoor units.
Equivalent piping length
(2)
: pipe length between outdoor
(1)
and
indoor units.
Total piping length: total piping length from the outdoor
(1)
to all indoor
units.
Difference in height between outdoor and indoor units: H1.
Difference in height between indoor and indoor units: H2.
Difference in height between outdoor and outdoor units: H3.
Difference in height between outdoor and BP unit: H4.
Difference in height between BP unit and BP unit: H5.
Difference in height between BP unit and RA indoor unit: H6.
(1) In case of multi outdoor system, re-read to the first outdoor unit multi connection
piping kit as seen from the indoor unit.
(2) Assume equivalent piping length of REFNET joint=0.5 m and REFNET
header=1 m (for calculation purposes).
9.4.2 System only containing VRV indoor units
System setup
Maximum allowable length
Between outdoor and indoor units (refer the recommend combination type in Engineering data book).
Branch with REFNET joint Branch with REFNET header
Single outdoor
Example 1:
Multi outdoor
Example 2:
Example 1.1
Example 1.3Example 1.2
Example 2.1
Indoor unit
REFNET joint
REFNET header
Outdoor multi
connection piping
kit
Actual piping length
165 m
Example 1.1
unit8:a+b+c+d+e+f+g+p≤165m
Example 1.2
unit6:a+b+h≤165m
unit8:a+i+k≤165m
Example 1.3
unit8:a+i≤165m
Equivalent length
(2)
190 m ———
Total piping length
1000 m
a+b+c+d+e+f+g+h+i+j+k+l+m+n+p
≤
1000 m
——
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
a
b
c d e f
i
k
j
g h
BA
1 2 3 4 5 6
7 8
H1
H2
a
cb d e f
i
g h
1 2 3 4 5 6 7
8
H1
H2
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
t
u
r
s
H1
H3
a
j k
b
1 2 3 4 5 6
7 8
c d e f g h
t
u
r
s
BA
H1
H3
H2
a
b
1 2 3 4 5 6 7
8
c d e f g h i
t
u
r
s
H1
H3
Branch with REFNET joint and REFNET
header
Between outdoor and indoor units (free multi combinations).
Actual piping length
135 m
Example 2.1
unit8:a+b+c+d+e+f+g+p≤135m
Example 2.2
unit6:a+b+h≤135m
unit8:a+i+k≤135m
Example 2.3
unit8:a+i≤135m
Equivalent length
(2)
160 m ———
Total piping length
500 m
a+b+c+d+e+f+g+h+i+j+k+l+m+n+p
≤
500m
——
Example 2.2
Example 2.3
i