HVAC EXCELLENCE QUESTIONS AND
ANSWERS WITH CORRECT UPDATE
Heat fwhich fcauses fa fchange fin ftemperature fof fa fsubstance fis fcalled sensible fheat,
Heat fadded fto fa fsubstance fwithout fa frise fin ftemperature; f(example: fliquid frefrigerant fto fgas) fthis
fprocess fla fcalled? latent fheat
Heat fadded fto fthe frefrigerant fin fvapor fstate fafter fthe fevaporation fprocess fis fcalled, superheat
A fscroll fcompressor fmoves frefrigerant fby fmeans fof; involute fspirals
The fmovement fof fheat fby fway fof ffluid for fis fcalled; fair convection
The fmovement fof fheat fthrough fa fsolid fobject fis fcalled; radiation
The fstandard funit ffor fmeasuring fthe fquantity fof fheat fin fa fsubstance fis British fThermal fUnit
A frefrigerant fgives fup fheat fwhen fit; it fcondenses
Why fmust frefrigerant fin fthe fsuction fline fbe fslightly fwarmer fthan fthe fsaturation ftemperature? prevent
fliquid fslugging fof fthe fcompressor.
It fis fdesirable ffor frefrigerant fin fthe fsuction fline fto fbe fslightly fsuperheated fin forder fto; insure fliquid
frefrigerant fdoes fnot fenter fthe fcompressor.,
The fstate fof fthe frefrigerant fin fthe fsuction fline fshould fbe low fpressure/ flow ftemperature fvapor
The fstate fof fthe frefrigerant fentering fthe fcondenser fis High fPressure/ fHighly fSuperheated fVapor
The fEvaporator Transfers fheat ffrom fthe frefrigerated fspace fto fthe frefrigerant
The fEvaporator Transfers fheat ffrom fthe frefrigerated fspace fto fthe frefrigerant
Which fof fthe ffollowing fis fnot fa fThermodynamic fProperty fof frefrigerant Flammability
The fsequential forder fof fsteps fin fthe fvapor-compression fprocess fare: Compression, fCondensation,
fExpansion, fVaporization
If fa f30 flb fcontainer fof f$-410A frefrigerant fhas fbeen fstored fover fnight fat f70 fdegrees fF, fthe fpressure fin fthe
fcylinder fshould fbe fapproximately 201 fDegrees fFaranheit
Fan fAirflow fpressures fare fusually fmeasured fin Inches fof fwater fcolumn
Zero fPsia f(pounds fper fsquare finch fabsolute) fis a fpressure fwhich fcannot fbe ffurther freduced
Zero fPsig f(pounds fper fsquare finch fgauge) The fsame fas fatmospheric fpressure
, The fTemperature fat fwhich fmoisture fwill fstart fto fcondense ffrom fthe fair fis fcalled Dew fPoint fTemperature
A fCompound fpressure fgauge fmeasures Pressure fand fVacuum
A fMechanical fshaft fseal fis fnecesssary fon fa Open fdrive fcompressor
Liquid fslugging fis Liquid frefrigerant fin fthe fcompressor fclearance fspace
The fClearance fspace fin fa freciprocating fcompressor has fan feffect fon fcompressor fcapacity
Which fof fthe ffollowing ftypes fof fair fconditioning fcompressors fis fmore fefficient Centrifugal
Which fof fthe ffollowing frepresnet fthe fright forder ffor fthe ffunctionsof fa fcondenser De-Superheats,
fCondenses, fand fSub-cools
Refrigerant fR-134a fvapor fenters fthe fcondenser fat f124psig, f100 fdegrees ffaranheit, fIt fleaves fas fa fliquid
ffrom fthe fcondenser, fsub-cooled f20 fdegrees ffaranheit, fand fthe fpressure fwill fbe fapproximately 124
fpsig
There fare f3 fbasic ftypes fof fcondensers, fair fcooled, fwater fcooled, fand evaporative fcooled
10 flbs fof frefrigerant fpassing fthrough fa fwater fcooled fcondenser fwill flose f20 fBTU fof fheat/ fpound. fIf f10#'s
fof fwater fpasses fthrough fthe fcondenser fwith fan fentering ftemp fof f80 fdegrees, fthe ftemp fof fthe fwater
fleaving fthe fcondenser fis 100 fdegrees ffaranheit
The fheat fremoved ffrom fthe frefrigerant fby fthe fcondenser fis both fsensible fand flatent fheat
An fenergy frecovery fventilator fis an fair fto fair fheat fexhanger fto frecover fheat
Which fof fhte ffollowing fcan fnot fbe fused fas fa flow fambient ftemperature fcontrol? Crankcase fregulating
fvalves
When ftesting fthe fefficiency fof fan fair fcooled fcondenser, fthe frefrigerant fcondensing ftemperature fshould
fbe fno fmore fthan f_____ fhigher fthan fthe fentering fair ftemp. 30 fdegrees
The fFirst ffunction fa fcondenser fmust fperform fis fto f___ fthe frefrigerant fbefore fcondesing fcan foccur.
De-Superheat
A fthermostatic fexpansion fvalve fis fdesigned fto fmaintain Constant fevaporator fsuperheat
The fthermostatic fexpansion fvalve fhas fthree foperating fpressures Evaporator, fSpring fand fSensing fbulb
fPressure
When fMounting fa fthermostatic fexpansion fvalve fsensor fbulb, fwhich fof fthe ffolling fis fNOT ftrue? It fmust
fbe finstalled flower fthan fthe fvalve fbody
In fan fair fconditioning fsystem fthat fuses fa fthermostatic fexpansion fvalve, fthe ftemperature fof fthe
fevaporator foutlet fwill fusually fbe: Warmer fthan fthe fevaporator finlet
An fautomatic fexpansion fvalve fis fbest fsuited: When fthe fsystem fload fremains ffairly fconstant
Which fof fthe ffollowing fis fnot ftrue fof fa fcapillary ftube fmetering fdevice? They fmaintain fa fconstant
fevaporator ftemperature
ANSWERS WITH CORRECT UPDATE
Heat fwhich fcauses fa fchange fin ftemperature fof fa fsubstance fis fcalled sensible fheat,
Heat fadded fto fa fsubstance fwithout fa frise fin ftemperature; f(example: fliquid frefrigerant fto fgas) fthis
fprocess fla fcalled? latent fheat
Heat fadded fto fthe frefrigerant fin fvapor fstate fafter fthe fevaporation fprocess fis fcalled, superheat
A fscroll fcompressor fmoves frefrigerant fby fmeans fof; involute fspirals
The fmovement fof fheat fby fway fof ffluid for fis fcalled; fair convection
The fmovement fof fheat fthrough fa fsolid fobject fis fcalled; radiation
The fstandard funit ffor fmeasuring fthe fquantity fof fheat fin fa fsubstance fis British fThermal fUnit
A frefrigerant fgives fup fheat fwhen fit; it fcondenses
Why fmust frefrigerant fin fthe fsuction fline fbe fslightly fwarmer fthan fthe fsaturation ftemperature? prevent
fliquid fslugging fof fthe fcompressor.
It fis fdesirable ffor frefrigerant fin fthe fsuction fline fto fbe fslightly fsuperheated fin forder fto; insure fliquid
frefrigerant fdoes fnot fenter fthe fcompressor.,
The fstate fof fthe frefrigerant fin fthe fsuction fline fshould fbe low fpressure/ flow ftemperature fvapor
The fstate fof fthe frefrigerant fentering fthe fcondenser fis High fPressure/ fHighly fSuperheated fVapor
The fEvaporator Transfers fheat ffrom fthe frefrigerated fspace fto fthe frefrigerant
The fEvaporator Transfers fheat ffrom fthe frefrigerated fspace fto fthe frefrigerant
Which fof fthe ffollowing fis fnot fa fThermodynamic fProperty fof frefrigerant Flammability
The fsequential forder fof fsteps fin fthe fvapor-compression fprocess fare: Compression, fCondensation,
fExpansion, fVaporization
If fa f30 flb fcontainer fof f$-410A frefrigerant fhas fbeen fstored fover fnight fat f70 fdegrees fF, fthe fpressure fin fthe
fcylinder fshould fbe fapproximately 201 fDegrees fFaranheit
Fan fAirflow fpressures fare fusually fmeasured fin Inches fof fwater fcolumn
Zero fPsia f(pounds fper fsquare finch fabsolute) fis a fpressure fwhich fcannot fbe ffurther freduced
Zero fPsig f(pounds fper fsquare finch fgauge) The fsame fas fatmospheric fpressure
, The fTemperature fat fwhich fmoisture fwill fstart fto fcondense ffrom fthe fair fis fcalled Dew fPoint fTemperature
A fCompound fpressure fgauge fmeasures Pressure fand fVacuum
A fMechanical fshaft fseal fis fnecesssary fon fa Open fdrive fcompressor
Liquid fslugging fis Liquid frefrigerant fin fthe fcompressor fclearance fspace
The fClearance fspace fin fa freciprocating fcompressor has fan feffect fon fcompressor fcapacity
Which fof fthe ffollowing ftypes fof fair fconditioning fcompressors fis fmore fefficient Centrifugal
Which fof fthe ffollowing frepresnet fthe fright forder ffor fthe ffunctionsof fa fcondenser De-Superheats,
fCondenses, fand fSub-cools
Refrigerant fR-134a fvapor fenters fthe fcondenser fat f124psig, f100 fdegrees ffaranheit, fIt fleaves fas fa fliquid
ffrom fthe fcondenser, fsub-cooled f20 fdegrees ffaranheit, fand fthe fpressure fwill fbe fapproximately 124
fpsig
There fare f3 fbasic ftypes fof fcondensers, fair fcooled, fwater fcooled, fand evaporative fcooled
10 flbs fof frefrigerant fpassing fthrough fa fwater fcooled fcondenser fwill flose f20 fBTU fof fheat/ fpound. fIf f10#'s
fof fwater fpasses fthrough fthe fcondenser fwith fan fentering ftemp fof f80 fdegrees, fthe ftemp fof fthe fwater
fleaving fthe fcondenser fis 100 fdegrees ffaranheit
The fheat fremoved ffrom fthe frefrigerant fby fthe fcondenser fis both fsensible fand flatent fheat
An fenergy frecovery fventilator fis an fair fto fair fheat fexhanger fto frecover fheat
Which fof fhte ffollowing fcan fnot fbe fused fas fa flow fambient ftemperature fcontrol? Crankcase fregulating
fvalves
When ftesting fthe fefficiency fof fan fair fcooled fcondenser, fthe frefrigerant fcondensing ftemperature fshould
fbe fno fmore fthan f_____ fhigher fthan fthe fentering fair ftemp. 30 fdegrees
The fFirst ffunction fa fcondenser fmust fperform fis fto f___ fthe frefrigerant fbefore fcondesing fcan foccur.
De-Superheat
A fthermostatic fexpansion fvalve fis fdesigned fto fmaintain Constant fevaporator fsuperheat
The fthermostatic fexpansion fvalve fhas fthree foperating fpressures Evaporator, fSpring fand fSensing fbulb
fPressure
When fMounting fa fthermostatic fexpansion fvalve fsensor fbulb, fwhich fof fthe ffolling fis fNOT ftrue? It fmust
fbe finstalled flower fthan fthe fvalve fbody
In fan fair fconditioning fsystem fthat fuses fa fthermostatic fexpansion fvalve, fthe ftemperature fof fthe
fevaporator foutlet fwill fusually fbe: Warmer fthan fthe fevaporator finlet
An fautomatic fexpansion fvalve fis fbest fsuited: When fthe fsystem fload fremains ffairly fconstant
Which fof fthe ffollowing fis fnot ftrue fof fa fcapillary ftube fmetering fdevice? They fmaintain fa fconstant
fevaporator ftemperature
