Daikin IM 986-2 VHC Installation & Maintenance Manual

Contents

Page 44 of 48 / IM 986-2TroubleshootingThe in and outs of R-410AR-410A is a non-ozone depleting blend of tworefrigerants - HFC-125 and HFC-32 in a fifty percentmixture R-410A exhibits higher operating pressure andrefrigeration capacity than R-22 R-410A is intendedfor use in new air conditioning applications that havetraditionally been used HCFC-22 (R-22) Due to highercapacity and pressure of R-410A, it must not be used inexisting R-22 systemsAlthough R-410A is non-flammable at ambienttemperature and atmospheric pressure, it can becomecombustible under pressure when mixed with airNote: R-410A should not be mixed with air underpressure for leak testing. Pressure mixtures of drynitrogen and R-410A can be used for leak testing.LubricationR-410A should be used only with polyester (POE)oil The HFC refrigerant components in R-410A willnot be compatible with mineral oil or alkylbenzenelubricants R-410A systems will be charged with theOEM recommended lubricant, ready for use with R-410AChargingDue to the zeotropic nature of R-410A, it shouldbe charged as a liquid In situations where vapor isnormally charged into a system, a valve should beinstalled in the charging line to flash the liquid to vaporwhile chargingMake certain that the recycle or recovery equipmentused is designed for R-410A The pressure of R-410Arefrigerant is approximately 60 percent greater thanthat of R-22 Pressure gauges require a range up to800 PSIG high side and 250 PSIG low side Recoverycylinders require a 400 PSIG rating – do not put R-410A in a 300 PSIG rated cylinderNote: Because a water source heat pump operatesunder a wide range of water and air temperatures, thevalues printed below are to be taken as suggestedpressure and temperatures. All McQuay watersource heat pumps are designed for commercialuse. The units are designed for the coolingmode of operation and fail safe to cooling. Thereversing valve is energized for the heating mode ofoperation.Superheat Head Pressure Water Delta T8 to 14 degrees 335-355 PSIG 10° to 14°All information above is based on ISO standard13256-1 and tested at these conditions.General Maintenance1 Normal maintenance on all units is generallylimited to filter changes. Units are provided withpermanently lubricated motors and require no oilingeven though oil caps may be provided2 Filter changes are required at regular intervals Thetime period between changes will depend uponthe project requirements Some applications suchas motels produce a lot of lint from carpeting andlinen changes, and will require more frequent filterchanges. Check filters at 60-day intervals for the firstyear until experience is acquired If light cannot beseen through the filter when held up to sunlight ora bright light, it should be changed A more criticalstandard may be desirable3 The condensate drain pan should be checkedannually and cleaned and flushed as required.4 Record performance measurements of volts, amps,and water temperature differences (both heating andcooling) A comparison of logged data with start-upand other annual data is useful as an indicator ofgeneral equipment condition5 Periodic lockouts almost always are caused by air orwater problems The lockout (shutdown) of the unitis a normal protective result Check for dirt in thewater system, water flow rates, water temperatures,airflow rates (may be a dirty filter), and airtemperatures If the lockout occurs in the morningfollowing a return from night setback, entering airbelow machine limits may be the causeRecycle/recovery equipment must be designated for R-410A. R-410A pressure is greater than R-22. Improperequipment can cause severe injury or death.WARNING