14 Piping installation
Installation and operation manual
24
RK RKXYQ8T7Y1B
VRV IV compressor unit for indoor installation
4P499900-1A – 2020.10
Manifold
Connections
Compressor unit
p< p>
R410A
N2
b
c
e
a
d
B
A
Circuit 1 and 2
together
C
g
h
A
f
i
B
C
C
C
D
D
RDXYQ
RDXYQ
h
h
i
i
g
g
f
f
5 HP
8 HP
Only circuit 1
i
B
h
A
C
C
Only circuit 2
C
C
f
B
g
A
a
Pressure reducing valve
b
Nitrogen
c
Weighing scales
d
Refrigerant R410A tank (siphon system)
e
Vacuum pump
f
Liquid line stop valve (circuit 2: to indoor units)
g
Gas line stop valve (circuit 2: to indoor units)
h
Gas line stop valve (circuit 1: to heat exchanger unit)
i
Liquid line stop valve (circuit 1: to heat exchanger unit)
A, B, C
Valves A, B and C
D
Refrigerant line splitter
Valve
State of valve
Valves A, B and C
Open
Liquid line and gas line stop
valves (f, g, h, i)
Close
NOTICE
The connections to the indoor units and to the heat
exchanger unit, and all indoor units and the heat
exchanger unit itself should also be leak and vacuum
tested. Keep any possible (field supplied) field piping
valves open as well.
Refer to the indoor unit installation manual for more details.
Leak test and vacuum drying should be done before the
power supply is set to the unit. If not, see also the flow
chart earlier described in this chapter (see
23]).
14.3.4
To perform a leak test
The leak test must satisfy the specifications of EN378‑2.
To check for leaks: Vacuum leak test
1
Evacuate the system from the liquid and gas piping to
–100.7 kPa (–1.007 bar)(5 Torr absolute) for more than 2 hours.
2
Once reached, turn off the vacuum pump and check that the
pressure does not rise for at least 1 minute.
3
Should the pressure rise, the system may either contain
moisture (see vacuum drying below) or have leaks.
To check for leaks: Pressure leak test
1
Test for leaks by applying a bubble test solution to all piping
connections.
2
Discharge all nitrogen gas.
3
Break the vacuum by pressurising with nitrogen gas to a
minimum gauge pressure of 0.2 MPa (2 bar). Never set the
gauge pressure higher than the maximum operation pressure of
the unit, i.e. 4.0 MPa (40 bar).
NOTICE
ALWAYS use a recommended bubble test solution from
your wholesaler.
NEVER use soap water:
▪ Soap water may cause cracking of components, such
as flare nuts or stop valve caps.
▪ Soap water may contain salt, which absorbs moisture
that will freeze when the piping gets cold.
▪ Soap water contains ammonia which may lead to
corrosion of flared joints (between the brass flare nut
and the copper flare).
14.3.5
To perform vacuum drying
To remove all moisture from the system, proceed as follows:
1
Evacuate the system for at least 2 hours to a target vacuum of
–100.7 kPa (–1.007 bar)(5 Torr absolute).
2
Check that, with the vacuum pump turned off, the target
vacuum is maintained for at least 1 hour.
3
Should you fail to reach the target vacuum within 2 hours or
maintain the vacuum for 1 hour, the system may contain too
much moisture. In that case, break the vacuum by pressurising
with nitrogen gas to a gauge pressure of 0.05 MPa (0.5 bar)
and repeat steps 1 to 3 until all moisture has been removed.
4
Depending on whether you want to immediately charge
refrigerant through the refrigerant charge port or first pre-charge
a portion of refrigerant through the liquid line, either open the
compressor unit stop valves, or keep them closed. See
25] for more information.
14.3.6
To insulate the refrigerant piping
After finishing the leak test and vacuum drying, the piping must be
insulated. Take into account the following points:
▪ Make sure to insulate the connection piping and refrigerant branch
kits entirely.
▪ Be sure to insulate the liquid and gas piping (for all units).
▪ Use heat resistant polyethylene foam which can withstand a
temperature of 70°C for liquid piping and polyethylene foam which
can withstand a temperature of 120°C for gas piping.
▪ Reinforce the insulation on the refrigerant piping according to the
installation environment.
Ambient
temperature
Humidity
Minimum thickness
≤30°C
75% to 80% RH
15 mm
>30°C
≥80% RH
20 mm
▪ If there is a possibility that condensation on the stop valve might
drip down into the indoor unit or into the heat exchanger unit
through gaps in the insulation and piping because the compressor
unit is located higher than the indoor unit or higher than the heat
exchanger unit, this must be prevented by sealing up the
connections. See below figure.
