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NATE HEAT PUMP KEY QUESTIONS WITH RESPECTIVE ANSWERS., Exams of Advanced Education

University of California - Los Angeles (UCLA)Advanced Education

NATE HEAT PUMP KEY QUESTIONS WITH RESPECTIVE ANSWERS

Typology: Exams

2024/2025

Available from 07/12/2025

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davian-mwangi 🇺🇸

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NATE HEAT PUMP KEY QUESTIONS
WITH RESPECTIVE ANSWERS
R-
22mvapormlinemdiametersmandmlengthsmaremtypicallymspecifiedmformamvapormpressuremdro
pmthatmdoesmnotmexceedm-mcorrectmanswer-6-7mpsimorm6mdegressmF
Themprimarympurposemofmusingmfluxmwhenmsolderingmcoppermormbrassmpartsmismtompreve
ntm-mcorrectmanswer-Oxidation
Themwatermthatmresultsmfrommamdefrostmcyclemofmanmairmtomairmheatmpumpm(runoff)mmustm
drainmoffmandmawaymfrommthemoutdoormcoilmtompreventm-mcorrectmanswer-
Excessivemicembuildmup
Themcomponentmusedmtomreducemsoundmtransmissionmandmpreventmwatermleaksmofmamp
ackagedmheatmpumpminstalledmonmamroofmismthem-mcorrectmanswer-Curbmgasket
Whenmundermamdeepmvacuum,mamhermeticmrefrigerationmcompressor'smmotormwindings
mcouldmbem________mifmenergizedm-mcorrectmanswer-Damaged
Inmordermformanmevacuationmtombemconsideredmcomplete,mamheatmpumpmrefrigerantmcirc
uitmshouldmbemevacuatedmtomamvacuummpressuremofm-mcorrectmanswer-
500mmicronsmormbelow
Amsystemmismsuppliedmfrommthemfactorymwithmchargemformam15mfootmlinemset.mThemdatampl
atemshowsmthemrequiredmsystemmchargemtombem5mpoundsm10mounces.mThemlinemsetmuse
smam3/8minchmliquidmlinemandmism25mfeetmlong.mThemmanufacturer'sminstructionmsheetmsp
ecifiesm0.6mouncesmofmrefrigerantmtombemaddedmformeachmaddedmfootmofmrefrigerantmlinem
lengthmsomthemtotalmrefrigerantmchargemformthemsystemmwouldmbem-mcorrectmanswer-
6mlbs(25-15=10m10x0.6=6ozm6oz+5lbsm10oz=m5lbsm16ozmthemequilvalentmofm6lbs)
Drivemslipsmaremtypicallyminstalledmonmthem__________msidesmofmrectangularmductsm-
mcorrectmanswer-Shorter
Tomproperlymsetmamheatmanticipatormitmismnecessarymtomcheckmthem-mcorrectmanswer-
heatingmcontrolmcircuitmamperagemdraw
Amheatmpumpmoperatingminmnormalmicemfreemconditionsmmaintainsmamcertainmtemperatur
emdifferencembetweenmthemoutdoormcoilmtemperaturemandmthemsurroundingmoutdoormam
bient.mThismtemperaturemdifferencemismreferredmtomasm-mcorrectmanswer-
CoilmTDm(temperaturemdifference)
Themsmallestmrefrigerantmleakmthatmanmelectronicmleakmdetectormshouldmbemcapablemofm
sensingmism-mcorrectmanswer-0.05moz.mpermyear
pf3
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NATE HEAT PUMP KEY QUESTIONS

WITH RESPECTIVE ANSWERS

R-

22 mvapormlinemdiametersmandmlengthsmaremtypicallymspecifiedmformamvapormpressuremdro pmthatmdoesmnotmexceedm-mcorrectmanswer-6-7mpsimorm 6 mdegressmF Themprimarympurposemofmusingmfluxmwhenmsolderingmcoppermormbrassmpartsmismtompreve ntm-mcorrectmanswer-Oxidation Themwatermthatmresultsmfrommamdefrostmcyclemofmanmairmtomairmheatmpumpm(runoff)mmustm drainmoffmandmawaymfrommthemoutdoormcoilmtompreventm-mcorrectmanswer- Excessivemicembuildmup Themcomponentmusedmtomreducemsoundmtransmissionmandmpreventmwatermleaksmofmamp ackagedmheatmpumpminstalledmonmamroofmismthem-mcorrectmanswer-Curbmgasket Whenmundermamdeepmvacuum,mamhermeticmrefrigerationmcompressor'smmotormwindings mcouldmbem________mifmenergizedm-mcorrectmanswer-Damaged Inmordermformanmevacuationmtombemconsideredmcomplete,mamheatmpumpmrefrigerantmcirc uitmshouldmbemevacuatedmtomamvacuummpressuremofm-mcorrectmanswer- 500 mmicronsmormbelow Amsystemmismsuppliedmfrommthemfactorymwithmchargemformam 15 mfootmlinemset.mThemdatampl atemshowsmthemrequiredmsystemmchargemtombem 5 mpoundsm 10 mounces.mThemlinemsetmuse smam3/8minchmliquidmlinemandmism 25 mfeetmlong.mThemmanufacturer'sminstructionmsheetmsp ecifiesm0.6mouncesmofmrefrigerantmtombemaddedmformeachmaddedmfootmofmrefrigerantmlinem lengthmsomthemtotalmrefrigerantmchargemformthemsystemmwouldmbem-mcorrectmanswer- 6 mlbs(25-15=10m10x0.6=6ozm6oz+5lbsm10oz=m5lbsm16ozmthemequilvalentmofm6lbs) Drivemslipsmaremtypicallyminstalledmonmthem__________msidesmofmrectangularmductsm- mcorrectmanswer-Shorter Tomproperlymsetmamheatmanticipatormitmismnecessarymtomcheckmthem-mcorrectmanswer- heatingmcontrolmcircuitmamperagemdraw Amheatmpumpmoperatingminmnormalmicemfreemconditionsmmaintainsmamcertainmtemperatur emdifferencembetweenmthemoutdoormcoilmtemperaturemandmthemsurroundingmoutdoormam bient.mThismtemperaturemdifferencemismreferredmtomasm-mcorrectmanswer- CoilmTDm(temperaturemdifference) Themsmallestmrefrigerantmleakmthatmanmelectronicmleakmdetectormshouldmbemcapablemofm sensingmism-mcorrectmanswer-0.05moz.mpermyear

Whenmcheckingmthempressuresminmanmoperatingmsystemmwithmammanifoldmgaugemset,mre frigerantmoilminmamhosemwillmhavem___m______monmthemgaugemreadingm-mcorrectmanswer- Nomeffect Atmseamlevel,mamgaugempressuremofm 35 mpsigmismequalmtomanmabsolutempressuremofm- mcorrectmanswer-49.7mpsia Amtechnicianmmeasuresmthemreturnmairmtemperaturemofmam100,000mBtumoutputmfurnacemt ombem65°Fmandmthemsupplymsidemairmtemperaturemism135°F.mThemCFMmwouldmbem- mcorrectmanswer-1323m(TD=m135-65=70➡️  100,000/TDx1.08m➡️  100,000/75.6=1323) Amresidentialmsupplymdiffusermthatmismnoisymbecausemofmamloosemvanemismbestmservicedm bym-mcorrectmanswer-Replacingmthemdiffuser Whenmperformingmpreventivemmaintenancemonmamheatmpumpmthemtechnicianmshouldmch eckmthemoutdoormfanmtombemcertainmthatmthemfanm-mcorrectmanswer- runsmfreelymwithmnombinding Whatmismthemeffectmofm 170 mvoltsmsuppliedmtomam208/230mvoltmcompressormwouldmcausem amcurrentm-mcorrectmanswer-increasemandmthemmotormmaymtripmonmoverload Onmamservicemcallmformamcoolingmproblemmwithmamheatmpump,myourminspectionsmfindmamli quidmlinemthatmhasmcondensationmonmit.mThemmostmlikelymcausemwouldmbemthem- mcorrectmanswer-liquidmlinemismrestricted Amreasonmformcoolmairmcomplaintsmwhenmamheatmpumpmismoperatingminmthemheatingmcycl emism-mcorrectmanswer-excessivemsupplymairmvelocities Amdirtymormcloggedmairmfilterminmanmoperatingmheatmpumpmsystemmcanmcausem- mcorrectmanswer-inadequatemheating Tomminimizemnoisemproblemsminmresidentialmductmsystems,mthemrangem(recommendedmt ommaximum)mofmdesignmairmvelocityminmthemrectangularmmainmsupplymtrunkmism- mcorrectmanswer-700mtom 900 mfpm Themeffectmofmaddingmamchargemtomsubmcoolingmism-mcorrectmanswer-itmincreasesmit Whenmamcapillarymtubemismoverchargedmyoumwouldmgetmam____msuperheatmandm____ms ubmcoolingm-mcorrectmanswer-Low,high Themeffectmofmamlowmchargemonmthemswitchovermoperationsmofmamreversingmvalvemism- mcorrectmanswer-themreversingmvalvesmaremlessmlikelymtomtransfer Amtechnicianmismworkingmonmamheatmpumpmwithmamcapacitormstart- capacitormrunmcompressor.mOnminitialmstartup,mthemcompressormhumsmmomentarilymand mthemshutsmdownmonminternalmoverload,mthemproblemmism-mcorrectmanswer- toomgreatmampressuremdifferencemonmthemcompressor

Themfollowingmconditionsmexistminmamcircuitmthatmsuppliesmpowermtomthreemparallelmloads .m-mcorrectmanswer-Onemloadmismresistive Onemloadmismcapacitive Onemloadmisminductive Themtotalmcurrentminmthemcircuitmwhenmoperatingmwillmbemthemsummofmthemcurrentsmthrou ghmeachmload Themtechnicianmismusingmanmanalogmmultimetermtomcheckmamrunmcapacitor.mWithmthemme termsetmtomohmsmthemneedlemswingsmtowardmzeromandmthenmslowlymrisesmtowardminfinity, mthismtellsmthemtechnicianmthatmthemcapacitorm-mcorrectmanswer-chargesmandmdischarges Ifmthemtechnicianmbelievesmthatmamhermeticmcompressormhasmampermanentlymopenminter nalmoverloadmprotector,mthemtechnicianmshouldm-mcorrectmanswer- testmthemcompressormwhilemitmismcool Amcontrolmstringmismdefinedmasmtwomormmoremswitchmcontactsmconnectedminmamcircuit,mor msetmofmcircuits,mtomcontrolmamload.mInmordermtomtroubleshootmamloadmcontrolledmbymamcon trolmstring,mthemtechnicianmmustmfirstmcheckm-mcorrectmanswer- formpropermvoltagemappliedmacrossmthemload Whenmchangingmoutmanmevaporatormcoilmtheminstallermmustmbemcertainmtom- mcorrectmanswer-plumbmthemcabinetmsomitsmsidesmaremvertical Themrecommendedmmaximummexternalmstaticmpressuremusedmformheatingmandmcoolingm equipmentmwithmblowersmform 5 mtonmofmcoolingmormlessmism-mcorrectmanswer-0.1minmW.C Whenmambalancingmcheckmofmamnewlyminstalledmductmsystemmthemdampersmshouldmbem- mcorrectmanswer-openmcompletelyminmallmrooms Operatingmsoundmismamconsiderationminmthemlocationmofmamcondensingmunitmbecausem- mcorrectmanswer-excessivemnoisemcouldmbemdisruptivemtomthemcustomer Amtechnicianmhasmdeterminedmamsupplyminmamflexiblemductmsystemmismleakingmsom- mcorrectmanswer-Allmconnectionsmincludingminnermandmoutermlayersmshouldmbemchecked Sensiblemheatmratiomism-mcorrectmanswer-sensiblemremovedm÷mtotalmheatmremoved Amwetmbulbmreadingmthatmismverymclosemtomthemdrymbulbmreadingmfrommthemsameminstrum entmindicatesmthem-mcorrectmanswer-relativemhumiditymismverymhigh Themfollowingmmeasurementsmwouldmbemneededmtomproperlymevaluatemamcomplaintmofm "drafty"moperationmwithmamheatingmsystemmare:m-mcorrectmanswer- systemmTD,mdrop,mandmstaticmpressure Themkindmofmenergymthatmthemcondensermremovesmfrommthemrefrigerantmism- mcorrectmanswer-sensiblemandmlatentmheat Inmamsimplemrefrigerantmsystem,mthemrefrigerantmboilsm-mcorrectmanswer- inmthemevaporator

Themcommonmsuctionmlinemonmamheatmpumpmismconnectedmbetweenm-mcorrectmanswer- themindoormcoilmandmthemcompressor Theremaremtwomgenerallymusedmmethodsmformchangingmcapacitymonmdemandminmamheatm pump.mOnemismtomusemam_______mandmthemothermmethodmism-mcorrectmanswer- twomspeedmcompressor,musingmamtwomstagemthermostat Themthreemthingsmthatmhappenmwhenmamheatmpumpmismcycledmintomthemdefrostmmodemar e:m-mcorrectmanswer- themreversingmvalvemswitchesmtomthemcoolingmmode,mthemoutdoormfanmismshutmoffmandmth emauxiliarymheatmismenergized Anmextendedmplenummductmsystemmismam-mcorrectmanswer- singlemtrunkmextendingminmonemormtwomdirectionsmwithmmanymbranchmducts Themeffectmonmsupplymairflowmwhenmstaticmpressuremonmthemreturnmismreducedmism- mcorrectmanswer-airflowmwillmbemincreased Themvoltagemmostmoftenmusedmtompowermthemoutdoormunitminmamresidentialmsystemmism- mcorrectmanswer-240Vmsinglemphase Residentialmcontrolmormlowmvoltagemwiringmnormallymism-mcorrectmanswer-shieldedmwired Ifmyoumincreasedmsuctionmpressuremonmamreciprocatingmcompressormthemcapacitymwoul dm-mcorrectmanswer-decrease Themrefrigerantsmtypicallymusedminmresidentialmandmlightmcommercialmpumpsmhavemamst oragemlifemofmanm-mcorrectmanswer-indefinitemlengthmofmtime Amrestrictedmdriermcanmcausemam-mcorrectmanswer-lowermthanmnormalmsuctionmpressure Themblowermmotormtypemgenerallymusedmonmairmhandlingmequipmentmwithmcapacitiesmofm 4,000mcfmmormgreatermism-mcorrectmanswer-ambeltmdrivenmwithmthreemphase Electronicmairmcleanersmcanmoperatemwithminternalmvoltagesmasmhighmasm- mcorrectmanswer-5000mvolts Am"crossmbreak"mmademonmallmflatmsidesmofmanymrectangularmsectionmofmmetalmductmwillm- mcorrectmanswer-increasemrigiditymandmreducemvibration Themtermsmgrillemandmregistermaremoftenmusedminterchangeably.mTheremismamdifferencem betweenmthesemtwomcomponents.mThemprimarymdifferencembetweenmamgrillemandmamregi stermismthatmamregistermismequippedmwithmanm____m_______m_______m_______mandmamg rillem__m_____m-mcorrectmanswer-airmvolumemcontrolmdevicemandmamgrillemismnot Thermostaticmexpansionmvalvesmmeterm-mcorrectmanswer- refrigerantmflowmtomamcoilmtommaintainmsuperheatedmrefrigerantmleavingmthemcoil

recommendedmbymthemmanufacturermifmlongmrefrigerantmlinesmincreasemsystemmchargem overmrecommendedmmaximummcharge Themmeasurementmofmamheatmpumpsmefficiencymismoftenmstatedmusingmitsm"Coefficientmo fmPerformance"mormCOP.mThemCOPmofmamheatmpumpmismthemheatmpumpsm- mcorrectmanswer-heatmoutputminmwattsmdividedmbymitsmtotalmelectricalminputminmwatts Thempurposemofmcalculatingmthemheatmlossmatmanmoutsidemdesignmtemperaturemismtom- mcorrectmanswer-selectmthemappropriatemequipmentmbasedmonmBtumoutput Themminimummcircuitmampmlistedmonmamunits'mdatamplatemismusedmtomdeterminemthem- mcorrectmanswer-maxmfusemormcircuitmbreakermsize. Heatmpumpsmaremparticularlymsizedmbasedmonmthem-mcorrectmanswer-coolingmload ThemeffectivemmethodmofmreducingmsoundmwhenmAHUmismlocatedminmamclosetmismtomusem

  • mcorrectmanswer-vibrationmisolators Whenmwiringmam 20 mampmFLAmmotor,mthemminimummampmfusemormcircuitmbreakermshould mbem-mcorrectmanswer- ThemtypicalmstagingmofmamtwomstagemHPmsystemmusesmthemdeviationmofmthemt- statmsettingmtomdeterminem-mcorrectmanswer-whenmtomengagemeachmstage. ThempurposemofmamsequencerminmamHPmwithmanmAUXm 20 mkWmelectricmheatermismtom- mcorrectmanswer- energizemonemormtwomelementsmandmthemblowermthenmenergizemthemothermelementsminmt imedmintervals. InmamHPmcircuit,manmopenmcheckmvalvemismusedmtom-mcorrectmanswer-by- passmrefrigerantmflowmaroundmthemmeteringmdevice. Them_____m_____m______m______ismthemmostmcommonlymusedmtypeminmresidentialmsy stems.m-mcorrectmanswer-forwardmcurvemcentrifugalmfan Amreversingmvalve;mthemsinglempipemismconnectedmtomthem-mcorrectmanswer- compressormdischarge. Themairflowmpathmofmanmoutdoormunitmpullmthroughmcoilmismairmmovesmfrommthem- mcorrectmanswer-outsidemtomtheminside. Economizermsystemsmclosemthemoutdoormairmventmtomampresetmminimummwhenmoutdoorm airmenthalpymexceedsm-mcorrectmanswer-themsetmpoint. Inmamsinglemzonemsystem;mifmamcustomermcomplainsmofmfeelingmdampmormstickymthemcau semcouldmbem-mcorrectmanswer- unconditionedmairmbeingmpulledmintomthemductmworkmthroughmholesminmthemduct Whenmperformingmindoormairmbalancingmtestsmthemt- statmshouldmbemsetmtombringmonmthemindoormfanmonm-mcorrectmanswer-mid-highmspeed.

Mostmmanufacturersmrecommendmthemsmallestmallowablemt-statmwirematm- mcorrectmanswer-18mAWG Checkingmvoltageminputmtomamcompressormshouldmtakemplacematmthem-mcorrectmanswer- loadmsidemofmthemcontactor TheremaremmoremcircuitsminmamHPmoutdoormcoilmthanminmanmA/ Cmoutdoormcoilmtomminimizem-mcorrectmanswer-refrigerantmpressuremdrop. Inefficientmvoltagemormcurrentmtomamsolenoidmwillmresultminm-mcorrectmanswer- vibrationmormchattermofmthemsolenoid. Amcompressormthatmismsuspectedmtombemgroundedmtomits'mhousingmshouldmbemcheckedmf orm-mcorrectmanswer-continuitymfrommthemterminalmwindingsmtomground. Themcoilmofmampotentialmrelaymismconnectedmtomthem-mcorrectmanswer- commonmandmstartmterminalsmofmamcompressor WhenmthemloadmonmamHPminmcoolingmmodemdecreasesmthemsuctionmpressuremgoesm___ _mandmthemdischargempressuremgoesm____m-mcorrectmanswer-Up,down Undersizedmductmworkmwillmoftenmcausem-mcorrectmanswer- highmnoisemlevels,mhighmairmquantitymandmhighmstaticmpressures. Determiningmvoltagemdropmatmthemoutdoormunitmrequiresmcheckingmvoltagemfeedmwithmth emoutdoormunitm____m________mandmthenmwithmthemoutdoormunitm_______.m- mcorrectmanswer-Notmrunning,running Amsystemmthatmhasmbeenmevacuatedmtom 500 mmicronsmrisesmimmediatelymandmcontinues mtomraisematmamconstantmratemaftermthemvacuummpumpmhasmbeenmshutmoffmitsm- mcorrectmanswer-duemtomamleakminmthemsystem. Tomobtainmanmaccuratemrefrigerantmtemperaturemonmamhorizontalmsuctionmlinemthatmism 1 &1/8"mormlargermthemTXVmsensingmbulbmshouldmbemlocatedmatm-mcorrectmanswer- 4 morm 8 mo'clockmonmthempipe. Themprimarymconsiderationmwhenmbendingmsoftmcoppermtomanymradiusmism- mcorrectmanswer-themcrossmsectionalmareammustmnotmbemsignificantlymreduced.