Daikin VRV IV Q+ Series Installer And User Reference Manual

Also see for RXYQQ10U7Y1B: Installation and operation manual

18 | Piping installationInstaller and user reference guide90RXYQQ8~20U7Y1BVRV IV Q+ series heat pump4P546229-1A – 2020.10Method 2: After power ONIf the system has already been powered on, activate setting [2‑21] (refer to "Toaccess mode 1 or 2" [4 122]). This setting will open field expansion valves toguarantee a refrigerant piping pathway and make it possible to perform the leaktest and the vacuum drying.DANGER: RISK OF ELECTROCUTIONNOTICEMake sure that all indoor units connected to the outdoor unit are powered on.NOTICEWait to apply setting [2‑21] until the outdoor unit has finished the initialisation.Leak test and vacuum dryingChecking the refrigerant piping involves:▪ Checking for any leakages in the refrigerant piping.▪ Performing vacuum drying to remove all moisture, air or nitrogen in therefrigerant piping.If there is a possibility of moisture being present in the refrigerant piping (forexample, water may have entered the piping), first carry out the vacuum dryingprocedure 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 surethat all the outdoor unit stop valves are firmly closed before performing leak testor vacuum drying.NOTICEMake sure that all (field supplied) field piping valves are OPEN (not outdoor unit stopvalves!) before you start leak test and vacuuming.For more information on the state of the valves, refer to "Checking refrigerantpiping: Setup" [491].18.3.2 Checking refrigerant piping: General guidelinesConnect the vacuum pump through a manifold to the service port of all stop valvesto increase efficiency (refer to "Checking refrigerant piping: Setup" [491]).NOTICEUse a 2-stage vacuum pump with a non-return valve or a solenoid valve that canevacuate to a gauge pressure of –100.7 kPa (−1.007 bar)(5 Torr absolute).NOTICEMake sure the pump oil does not flow oppositely into the system while the pump isnot working.