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 34 page image

IM 893-10 • ROOFPAK SINGLEZONE UNITS 34 www.DaikinApplied.comM eChanICal InsTallaTIonRefrigerant ChargeEach unit is designed for use with R-410A.The total charge percircuit is the sum of the following four values:• Condenser section charge, see Table 11 on page 32.• Evaporator coil charge, see Table 11.• Charge for length of unit piping to the evaporator coil, seeTable 11.• Charge for length of interconnecting piping between theRCS and RFS units, installed by field, see Table 12. Theexact charge for a one piece RPS/RDT is on the unitnameplate.Field Charging ProcedureUnder normal (summertime) operating conditions, thesuperheat at the compressor should be between 8ºF and 14ºFand subcooling measured at the condenser outlet should be15ºF (nominal).With all compressors operating at full capacity, a 25ºF-35ºFtemperature difference should exist between the enteringcondenser air and the temperature corresponding to thecompressor saturated discharge pressure.For VFD compressor units, set the VFD compressor capacityto 100% before measuring subcooling.The recommended method for field charging would be torecover, evacuate and re-charge the system to the value onthe unit nameplate. If this method is not practical or verificationof charge is the purpose, then unit charge can best evaluatedby the amount of subcooling.Follow Table 15 below for acceptable subcooling levels. Tocalculate subcooling: take the difference between the liquidtemperature leaving the condenser and the temperaturecorresponding to the compressor saturated dischargepressure. It is important not to use the saturation pressureat the condenser outlet as this will lead to an overchargedstate When charging at ambients below 75ºF it is stronglyrecommended to recover, evacuate and re-charge the unit tothe value on the unit nameplate.Table 15: Typical Subcooling Operating ValuesOutdoor Ambient Subcooling Range (see notes)75–85ºF 5–10ºF85–95ºF 10–15ºF95–105ºF 15–20ºF1. All compressors in circuit operating at full capacity2. All condenser fans operating3. Speedtrol condenser fan motor(s) operating at 100% (if option present)4. Hot Gas Bypass not operating5. MHGRH and liquid subcooling should not be operatingThese units contain a microchannel condenser and the internalvolume of the refrigeration system is less than that comparedto a typical fin-tube condenser. Unit refrigerant charge can beas much as 40% less with microchannel and is much moresensitive to charge levels. Caution should be exercised not toovercharge the unit.Refrigeration Service ValvesUnits are shipped with a liquid line charging valve in eachcircuit. RDT, RPS and RCS units have the following:RDT, RPS and RCS Units—One liquid charging valve isprovided per refrigeration circuit, located at end of condensingsection opposite condenser control box.Optional—One discharge valve and one suction valve isprovided for each refrigerant circuit, located in the condensersection. If the unit contains a discharge and suction valve,verify that the valves are open before attempting to start thecompressors.RFS units—do not contain service valves.