Carrier AquaEdge 19XR Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR: Controls operation and troubleshooting Start-up, operation and maintenance instructions Start-up, operation and maintenance instructions

Carrier AquaEdge 19XR Start-up, Operation And Maintenance Instructions Manual Manual pdf 18 page image

18Chiller DehydrationDehydration is recommended if the chiller has been open for aconsiderable period of time, if the chiller is known to containmoisture, or if there has been a complete loss of chiller holdingcharge or refrigerant pressure.Dehydration can be done at room temperatures. Using a coldtrap (Fig. 12) may substantially reduce the time required tocomplete the dehydration. The higher the room temperature,the faster dehydration takes place. At low room temperatures, avery deep vacuum is required to boil off any moisture. If lowambient temperatures are involved, contact a qualified servicerepresentative for the dehydration techniques required.Perform dehydration as follows:1. Connect a high capacity vacuum pump (5 cfm [.002 m3/s]or larger is recommended) to the refrigerant chargingvalve (Fig. 2). Tubing from the pump to the chiller shouldbe as short in length and as large in diameter as possible toprovide least resistance to gas flow.2. Use an absolute pressure manometer or a digital vacuumgage to measure the vacuum.3. If the entire chiller is to be dehydrated, open all isolationvalves (if present).4. With the chiller ambient temperature at 60°F (15.6°C) orhigher, operate the vacuum pump until the manometerreads 185 psig (1275 kPa), or a vacuum indicator reads35°F (1.7°C). Operate the pump an additional 2 hours.Do not apply a vacuum greater than 29.82 in. Hg vac(757.4 mm Hg) or go below 33°F (0.56°C) on the wet bulbvacuum indicator. At this temperature and pressure, isolat-ed pockets of moisture can turn into ice. The slow rate ofevaporation (sublimation) of ice at these low temperaturesand pressures greatly increases dehydration time.5. Valve off the vacuum pump, stop the pump, and record theinstrument reading.6. After a 2-hour wait, take another instrument reading. If thereading has not changed, dehydration is complete. If thereading indicates vacuum loss, repeat Steps 4 and 5.7. If the reading continues to change after several attempts,perform a leak test up to the maximum 160 psig (1103 kPa)pressure. Locate and repair the leak, and repeat dehydration.8. Once dehydration is complete, the evacuation process cancontinue. The final vacuum prior to charging the unit withrefrigerant should in all cases be 29.9 in. Hg (500 microns,0.07 kPa [abs]) or less.Inspect Water PipingRefer to piping diagrams provided in the certified drawingsand the piping instructions in the 19XR Installation Instruc-tions manual. Inspect the piping to the cooler and condenser.Be sure that the flow directions are correct and that all pipingspecifications have been met.Piping systems must be properly vented with no stress on wa-terbox nozzles and covers. Water flows through the cooler andcondenser must meet job requirements. Measure the pressuredrop across the cooler and the condenser.Check Relief ValvesBe sure the relief valves have been piped to the outdoors incompliance with the latest edition of ANSI/ASHRAE Standard15 and applicable local safety codes. Piping connections mustallow for access to the valve mechanism for periodic inspec-tion and leak testing.The standard 19XR relief valves are set to relieve at 185 psig(1275 kPa) chiller design pressure.Inspect Wiring1. Examine the wiring for conformance to the job wiring dia-grams and all applicable electrical codes.2. Compare the ampere rating on the starter nameplate to rat-ing on the compressor nameplate. The overload trip ampsmust be 108% to 120% of the rated load amps.3. The starter for a centrifugal compressor motor must con-tain the components and terminals required for PIC 5 con-trols platform. Check the certified drawings.4. Check the voltage to the components and compare it to thenameplate values.5. Ensure that fused disconnects or circuit breakers havebeen supplied for the control panel.CAUTIONDo not start or megohm-test the compressor motor or oilpump motor, even for a rotation check, if the chiller is un-der dehydration vacuum. Insulation breakdown and severedamage may result.WARNINGStarters must be disconnected by an isolation switch beforeplacing the machine under a vacuum. To be safe, isolateany starter before evacuating the chiller if you are not sureif there are live leads to the hermetic motor.CAUTIONWater must be within design limits, clean, and treated to en-sure proper chiller performance and to reduce the potentialof tube damage due to corrosion, scaling, or erosion. Carri-er assumes no responsibility for chiller damage resultingfrom untreated or improperly treated water.WARNINGDo not check the voltage supply without proper equipmentand precautions. Serious injury may result. Follow powercompany recommendations.CAUTIONDo not apply any kind of test voltage, even for a rotationcheck, if the chiller is under a dehydration vacuum. Insula-tion breakdown and serious damage may result.Fig. 12 — Dehydration Cold Trap