Daikin RYYQ8U7Y1B, Installer And User Manual

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17 | Piping installation
Installer and user reference guide
94
RYYQ+RYMQ+RXYQ
VRV IV+ heat pump
4P546228-1C – 2021.11
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).
17.3.5 To perform vacuum drying
NOTICE
The connections to the indoor units and all indoor units should also be leak and
vacuum tested. Keep, if existing, all (field supplied) field valves to the indoor units
open as well.
Leak test and vacuum drying should be done before the power supply is set to the
unit. If not, see
"17.3.1 About checking the refrigerant piping" [
4
91] for more
information.
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
"17.4.2 About charging refrigerant" [
4
96] for more information.