Daikin RDT Installation And Maintenance Manual

Also see for RPS: Installation and maintenance manual Installation and maintenance manual Installation manual Manual

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Daikin RDT Installation And Maintenance Manual Manual pdf 104 page image

IM 893-10 • ROOFPAK SINGLEZONE UNITS 104 www.DaikinApplied.comC heCk , TesT, and sTarTCompressor StartupCAUTIONLow ambient temperature hazard. Can cause compressordamage. Do not attempt to start up and check out therefrigeration system when the outdoor air temperature isbelow 50°F unless the unit is specially equipped for lowambient operation.Inspect all refrigerant piping and look for leaks by looking forrefrigerant oil residue. If any problem is found, reclaim anyremaining refrigerant, fix the problem and then add the circuit’snameplate charge by weight before proceeding.With the supply and return fans operational, prepare forcompressor operation.If the unit contains optional refrigeration service valves, theywill be shipped closed. Open the discharge and suction valves.The valve are a quarter-turn ball valve type. Verify that the unithas not lost its refrigerant charge. Check the compressor oillevel before startup. The oil level should be at or slightly abovethe center of the sight glass.Verify that the crankcase heaters are operating. These shouldoperate for at least 24 hours before starting the compressors.NOTE: On VFD compressors VZH088 and VZH117, verifythat the VFD is powered and providing a DC holdingcurrent to the compressorwhen the compressor isOFF. The holding current heats the compressor motorand is used in place of an external banded crankcaseheater. The local control panel on the VFD will displaythat a holding current is present.Verify that the condenser fan blades are positioned properlyand that the screws are tight (see Figure 108). The fan blademust be correctly positioned within its orifice for proper airflowacross the condenser coils.Figure 108: Condenser Fan Blade PositioningScroll Compressor Rotational DirectionScroll compressors only compress in one rotational direction.Three-phase compressors can rotate in either directiondepending upon phasing of the power to L1, L2, and L3.Since there is a 50/50 chance of connecting power to causerotation in the reverse direction, verify that the compressorrotates in the proper direction after the system is installed. Ifthe compressor is rotating properly, suction pressure drops anddischarge pressure rises when the compressor is energized. Ifthe compressor is rotating in reverse, the sound level is louderand current draw is reduced substantially. After several minutesof operation, the compressor’s motor protector trips.All three-phase compressors are wired the same internally.Therefore, once the correct phasing is determined for aspecific system or installation, connecting properly phasedpower leads to the same terminals should maintain properrotational direction.On VFD compressors, if reverse rotation is noted at startup,the power leads (U and W) at the compressor should bereversed. Reversing the VFD’s incoming power leads will notchange the compressor’s rotational direction.Perform the following procedure on all units:1. At the keypad, set the cooling setpoint low enoughso that the controller will call for cooling. The valuein View\Set Unit\Cooling\Occ Clg Spt will need to beadjusted below the temperature shown in View\Set Unit\Temperatures\Control Temp. In addition, on DAC units,the value in View\Set Unit\Cooling\DAT Clg Spt will needto be adjusted below the temperature shown in View\SetUnit\Temperatures\Discharge Temp.2. Place the unit into cooling mode through the keypadmenu Quick Menu\Ctrl Mode = Cool Only.3. Verify that the low ambient compressor lockouttemperature setpoint, Main Menu\Commission Unit\Cooling Setup\Clg Lo OAT Lk is set below the currentoutside air temperature (shown in View\Set Unit\Temperatures\OA Temp).NOTE: Do not attempt to operate the compressors if theoutdoor air is too cool. See the caution statementunder “Compressor Startup”.4. Close the S1 switch. Now refrigeration circuit #1 isenabled and circuit #2 is disabled. After CS1 is closed,the MT III board starts its 5-minute timing cycle. Notethat if the unit has an economizer and the outdoor airenthalpy is low, the economizer must fully open beforethe controller will energize mechanical cooling.5. When the outdoor air damper has fully opened and thetime delay has expired, the liquid line solenoid SV1 andthe compressor should start.a. Verify that there is a call for cooling by checkingthe keypad menu Quick Menu\Unit State =. Thisshould be in Cooling.b. Check the keypad menu Main Menu\View\Set Unit\Unit Status\Settings\Clg Status =. Thecompressors will only run if this reads (Enabled).c. Trace the control circuits.NOTICEVenting refrigerant to atmosphere is not allowed per mostlocal laws and/or codes.1.21"