flushing issues on large commercial ground loops
TRANSCRIPT
Dominique DurbinDurbinGeothermal
Flushing Issues on Large Commercial Ground Loops
Breakout Session CategoryCommercial
Learning Objectives• Understand Basic Flushing Requirements• Understand Flushing Equipment• Anticipate Potential Future Issues• Apply Concepts to Designs
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Content Slides
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FlowRateRequiredtoAchieve2ft/sec
AccreditedGeoExchange InstallerTraining
Nominal Pipe Size (Inches)
Pipe ID (Inches)
Flow Rate (GPM)
¾" 0.860" 4.3 GPM
1" 1.077" 5.7 GPM
1 ¼" 1.358" 9.0 GPM
1 ½" 1.554" 11.8 GPM
2" 1.943" 18.4 GPM
¾" 0.824" 3.3 GPM
1" 1.049" 5.4 GPM
1 ¼" 1.380" 9.3 GPM
1 ½" 1.610" 12.7 GPM
2" 2.067" 20.9 GPM
High Density Polyethylene, SDR - 11
High Density Polyethylene, SCH 40
FlowRatestoAchieve2ft/sec
AccreditedGeoExchangeInstallerTraining
Velocity=Gal/Min*1cubicft/7.48Gal*1min/60sec*1/Areaofpipe=Ft/Second
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ThoroughlyRinseandCleanEachLoopBeforeHeaderConnectionThoroughlyRinseandCleanEachPodBeforeConnectiontoVaultorMainsRecordVolumeofWaterUsedtoCleanPodsFlushataRateOver2ft perSecondThroughallConnectedPipingChangeFlowDirectionandRepeatFlushingUntilAllAirisRemovedRecordFlowRateandInandOutPressuresPressurizetoFlexandStretchPipe,RelaxingandRepeatingasNecessaryPressurizeandMonitorAccordingtoSpecificationsorManufacturerTestProcedureRecordPressuresandTimesHaveaWitnessorOwner’sRepresentativeSignDocumentationofProceduresandTests
FlushingProcedure
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AFlowRateof6FtPerSecondisRequiredtoRemoveDirtandDebris
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SmallSchoolinCentralIllinois
50Boreholeswith1”Loops5Podsof10Loopson3”HeadersBuriedValveCircuitrywithOutsideFlushPorts6”MainstoBuilding
ApproximateVolumes:EachLoop28GallonsEachPod450to500GallonsLoopFieldtoFlushPorts2500to2700Gallons
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FlushingRequirementsRinsing:EachLoop:90Gallonsat18GPMEachPod:1500Gallonsat650GPM
Purging:EachLoop Air:6GPM Debris18GPMEachPod Air:210GPM Debris650GMP
Content Slides
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ExteriorBuriedFlushPortsBeforeConcreteBoxisInstalled
Conclusion
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HighSchoolinBolivar,MOInstalled20YearsAgo200TonSystemwithExternalFluidCooler8”Mains4”Pods1Setof2”LinestoMaintenanceBuilding
Problem:ReducingPerformanceClimbingLoopTemperaturePumpsWearingOutScheduledforUnitstobeChangedNextYear
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Dorm/ApartmentBuilding inChampaign,ILNewFiberOpticLineDirectionallyDrilledDirectlyThrough LoopFieldIthappenedonaFridayAfternoon.MaintenancePeopleShutitOffMondayMorning.MakeUpWaterRanContinuouslyAllWeekend.
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¾”FlushPorts
2”Pods
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DesignandInstallationDay4”Mains2”Podsof10300ft 1”Loops¾”FlushPortsPurging RequirementsAirRemoval:72GPMDebrisRemoval:212GPMItisHighlyUnlikelythattheSystemWasEverProperlyFlushed
CutRepairDay:12”HeaderSectionCut11¼”HeaderSectionCut21”LoopsCutPurging Requirements:NoChange
Solution:FlushOpenLoopsIndividually thenRepairLoopsFlushOpenHeadersIndividuallyFromBothDirectionsthenRepairHeadersFlushSystem1PodataTimeUsingFlushCart,BoostPump,andsystemPumps
AirwasSuccessfullyRemovedMostDebrisRemoved.MaintenancePeopleDecreasedScreenSlotSizesandplanned toInspectandChangeRegularly
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LargeCentralPlantCampusLoopFieldUniversityofMissouriScienceandTechnologyRolla,MOLot11andWellField3135Boreholes440ft Deep10”Mains9Podsof15on3”
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SystemCapacity:11,250Gallons
10”Pipeholds350GallonsPer100ft2CityBlocksisabout650ftThatMeans2,275GallonsMustbePumpedBeforeWaterReachestheFirstPodLoopUsingaTypical1000GallonReservoiranda200GPMFireHydrantIfOurGalisAirRemoval:TankisEmpty(OrLowEnoughtoIntroduceAir)in3MinutesIfOurGoalisDebrisRemoval:TankisEmptyinUnder1Minute
Usinga6,000GallonTankerReservoirAir:TankWillKeepUpfor21MinutesDebris:TankWillKeepUpfor5Minutes
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Conclusions:
FlushPortsMustBeAppropriatelySizedSystemPumpsareNotAdequatetoCleantheInsideofBuildingsExteriorFlushPortsMinimizeImpactToOwnersorOccupantsonFutureRepairsBypassesareBeneficialinCleaningDamagedSystemsTheAbilityToRecirculateFluidisNotGuaranteedProperFlushingRequiresLargeReservoirsandMakeUpWater
