14 Piping installation
Installation and operation manual
24
RXYQQ8~20U7Y1B
VRV IV Q+ series heat pump
4P546221-1B – 2020.10
Valve
State of valve
Gas line stop valve
Close
NOTICE
The connections to the indoor units and all indoor units
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. 3.3 MPa (33 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
outdoor 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 through gaps in the insulation and
piping because the outdoor unit is located higher than the indoor
unit, this must be prevented by sealing up the connections. See
below figure.
a
b
a
Insulation material
b
Caulking etc.
14.4
Charging refrigerant
14.4.1
Precautions when charging refrigerant
WARNING
▪ ONLY use R410A as refrigerant. Other substances
may cause explosions and accidents.
▪ R410A contains fluorinated greenhouse gases. Its
global warming potential (GWP) value is 2087.5. Do
NOT vent these gases into the atmosphere.
▪ When charging refrigerant, ALWAYS use protective
gloves and safety glasses.
NOTICE
If the power of some units is turned off, the charging
procedure cannot be finished properly.
NOTICE
In case of a multiple outdoor system, turn on the power of
all outdoor units.
NOTICE
Be sure to turn ON the power 6 hours before operation in
order to have power running to the crankcase heater and
to protect the compressor.
