18 | Piping installation
Installer and user reference guide
93
REYQ8~20+REMQ5U7Y1B
VRV IV+ heat recovery
4P561154-1A – 2020.10
NOTICE
Make sure that all indoor units connected to the outdoor unit are powered on.
NOTICE
Wait to apply setting [2‑21] until the outdoor unit has finished the initialisation.
Leak test and vacuum drying
Checking the refrigerant piping involves:
▪ Checking for any leakages in the refrigerant piping.
▪ Performing vacuum drying to remove all moisture, air or nitrogen in the
refrigerant piping.
If there is a possibility of moisture being present in the refrigerant piping (for
example, water may have entered the piping), first carry out the vacuum drying
procedure below until all moisture has been removed.
All piping inside the unit has been factory tested for leaks.
Only field installed refrigerant piping needs to be checked. Therefore, make sure
that all the outdoor unit stop valves are firmly closed before performing leak test
or vacuum drying.
NOTICE
Make sure that all (field supplied) field piping valves are OPEN (not outdoor unit stop
valves!) before you start leak test and vacuuming.
For more information on the state of the valves, refer to "Checking refrigerant
piping: Setup"[494].
18.3.2 Checking refrigerant piping: General guidelines
Connect the vacuum pump through a manifold to the service port of all stop valves
to increase efficiency (refer to "Checking refrigerant piping: Setup"[494]).
NOTICE
Use a 2-stage vacuum pump with a non-return valve or a solenoid valve that can
evacuate to a gauge pressure of –100.7kPa (−1.007bar)(5Torr absolute).
NOTICE
Make sure the pump oil does not flow oppositely into the system while the pump is
not working.
NOTICE
Do NOT purge the air with refrigerants. Use a vacuum pump to evacuate the
installation.
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