Pipe Size Selection - Hitachi RAS-4FSNME1 Instruction Manual

PIPING WORK

8.3 PIPE SIZE SELECTION

Select the pipe size in line with the following instructions:
• Between the outdoor unit and the branch pipe (Multi-Kit):
select the same pipe connection size as for the outdoor unit.
• Between the branch pipe (Multi-Kit) and the indoor unit:
select the same pipe connection size as for the indoor unit.
!
C A U T I O N
• Do not use refrigerant pipe sizes other than those indicated in the
technical information. The diameter of the refrigerant pipes depends
directly on the power of the outdoor unit.
• If larger diameter refrigerant pipes are used, the circuit lubrication oil
tends to separate from the gas carrying it. The compressor will be
seriously damaged due to a lack of lubrication.
• If smaller diameter refrigerant pipes are used, the gas or liquid
refrigerant will have serious difficulties in circulating. System
performance will be affected. The compressor will run under more
severe conditions than foreseen and will be damaged in a short
space of time.
• Select the piping size with the correct thickness and correct material
which can have sufficient pressure strength.
8.3.1 Heat pump systems
A
1
?
N O T E
Only for Hydro Free combinations maximum connection ratio is up to
200%

Main pipe diameter (from the OU to the first branch)
Outdoor unit
RAS-(4-6)FS(V)NME1
RAS-8FSXNME1
RAS-10FSXNME1
RAS-12FSXNME1
?
N O T E
• In the case that the piping length from the Multi-Kit at the first branch
to the terminal indoor unit is over 40m, the size of the main piping
should be increased by one size (with E-162SN4 or E-242SN3 (*1)).
• When the maximum length of the equivalent refrigerant pipe from the
outdoor unit to the indoor unit is over 70 m for RAS-(4-6)FS(V)NME1
or over 100 m for RAS-(8-12)FSXNME1, the pipe size of liquid line
of the main pipe should be increased by one size ( with E-162SN4 or
E-242SN3 (*1)).

Pipe diameter after first branch or between multi-kits
Total indoor unit capacity
after the first branch (HP)
<6
(6-8.99)
(9-11.99)
(12-15.6)
19 PMML0532 rev.1 - 12/2020
C
2
3 3 3
IU IU IU
2
2
3
3 3
B
B
IU IU IU
Gas Liquid
ø15.88 ø9.52
ø19.05 ø9.52
ø22.20 ø9.52
ø25.40 ø12.70
Gas Liquid
ø15.88 ø9.52
ø19.05 ø9.52
ø22.20 ø9.52
ø25.40 ø12.70
?
N O T E
If the multi-kit size is larger than the first branch,adjust the multi-kit size to
the first branch. In case that the selected pipe size after the first branch is
larger than the pipe size before the first branch, use the same pipe size
≥
as after the branch (pipe pipe).

Pipe diameter between multi-kit and indoor unit
Indoor unit capacity (HP)
0.4-1.5
2
2.5-6.0
8.0
10.0
?
N O T E
• (*): When the liquid piping length is longer than 15m, use Ø9.52 pipe
and reducer (field-supplied).
• The pipe diameter should be the same as the IU piping connection
size. Check the corresponding IU connection sizes.
A First branch and B multi-kits after the first branch
A B
Outdoor unit HP Total indoor unit HP
4-10
12
C Header branch
Total indoor unit HP Nº of header branches
2-8
4-10
Gas Liquid
ø12.70 ø6.35 (*)
ø15.88 ø6.35 (*)
ø15.88 ø9.52
ø19.05 ø9.52
ø22.20 ø9.52
Model
E-102SN4
<12
(*1) E-162SN4
E-162SN4
12-15.6
(*1) E-242SN3
Model
4 MH-84AN1
8 MH-108AN