CR-39 HVAC EXAM MARCH 2025 WITH CORRECT QUESTIONS AND ANSWERS

CR-39 HVAC EXAM MARCH 2025 WITH
CORRECT QUESTIONS AND
ANSWERS
Refrigerant4electronic4controls4and4sensors4would4be4found4where4in4the4design4
of4the4system?
A)4electronic4control4schedule
B)4ladder4diagram
C)4system4plan
D)4piping4schedule4diagram4-4answer-B)4ladder4diagram

WHat4is4the4maximum4temperature4for4any4flame4or4surface4in4a4mechanical4Ro
om?
A)46004degrees
B)44254degress
C)48004degress
D)42504degress4-4answer-C)48004degress

Never4test4a4refrigeration4system4with4nitrogen4in4excess4of4what4pressure4if4the
4manufacturers4label4doesnt4specify4limits?
A)41504psi
B)41904psi
C)41704psi
D)41804psi4-4answer-C)41704psi

What4type4of4copper4tubing4would4be4used4if4you4had4to4make4a4flange4connect
ion4with4141/84copper4pipe?
A)4k4soft4drawn
B)4k4hard4drawn
C)4L4hard4drawn
D)4L4soft4drawk4-4answer-D)4L4soft4drawn

What4factor4determines4heat4transfer4through414sq.4ft4of4insulation,41"4thick4to4pr
oduce4a414degree4F4heat4gain
A)4k4factor
B)4u4value
C)4perm4value
D)4r4value4-4answer-A)4K4factor

In4a4flooded4evaporator4system4where4is4the4surge4drum4located
A)4above4the4evaporator
B)4beside4the4evaporator
C)4below4the4evaporator
D)4where4easiest4to4install4-4answer-A)4above4the4evaporator

,To4check4efficiency4of4a4refrigeration4system4what4is4the4first4measurement4one4
should4take
A)4evaporator4inlet4pressure
B)4compressor4inlet4pressure
C)4condenser4outlet4pressure
D)4compressor4outlet4pressure4-4answer-D)4compressor4outlet4pressure

Where4is4the4sulfide4cell4located4in4a4low4pressure4broiler4system
A)4the4fresh4air4supply
B)4the4ductwork
C)4the4burner
D)4the4pilot4assembly4-4answer-C)4the4burner

WHat4is4the4maximum4distance4between4the4flame4and4a4(cadmium)4sulfide4flam
e4sensor4for4the4sensor4to4be4placed?
A)418"
B)24"
C)412"
D)46"4-4answer-A)418"

IF4two4refrigeration4systems4are4installed4on4a4buildings4roof4what4of4the4followin
g4is4correct
A)4they4must4be4spaced4a4minimum4of464ft4apart
B)4they4must4be4anchored4to4the4roofing4system
C)4they4must4have4permanent4identification4for4the4service4area
D)4they4must4have4a4common4electrical4branch4circuit4-4answer-
C)4they4must4have4permanent4identification4for4the4service4area

AT4what4soil4depth4is4the4temperature4of4the4soil4equal4to4the4average4annual4a
ir4temperature4
A)420'
B)431'
C)429'
D)418'4-4answer-A)420'

If4using4extracted4refrigerant4system4is4low4pressure4liquid4refrigerant4found
A)41324degrees4F
B)41144degrees4F
C)41284degrees4F
D)41204degrees4F4-4answer-D)41204degrees

Cooling4towers4reduce4water4temperature4through4what4physical4process?
A)4condensation
B)4sublimation
C)4evaporation

,D)4hydration4-4answer-C)4evaporation

Starting4relays4are4used4hermetic4compressor4systems4to4drop4what4from4the4cir
cuit?
A)4condenser
B)4running4motor4windings
C)4capacitor
D)4starter4motor4windings4-4answer-D)4starter4motor4windings

How4often4should4a4blow4down4test4of4the4low4water4fuel4valve4cutoff4be4perfor
med4on4a4low4pressure4boiler?
A)4monthly
B)4daily
C)4yearly
D)4weekly4-4answer-D)4weekly

One4of4the4benefits4of4the4spring4loaded4pressure4relief4valve4is4that4it4is?
A)4inexpensive
B)4reseals4itself
C)4takes4higher4pressures
D)4easy4to4replace4-4answer-B)4reseals4itself

The4pH4of4the4boiler4water4should4be?
A)41.54to42
B)43.54to46
C)494to410
D)4144to4184-4answer-C)49-10

In4a4larger4refrigeration4installation,4two4compressor4designs4prove4greater4refriger
ation4capacity4and4an4example4of4such4a4system4would4be?
A)4switching4compressor4assemblies
B)4none4of4the4above
C)4shunting4compressor4assemblies
D)4parallel4assembly4motor4assemblies4-4answer-
D)4parallel4assembly4motor4assemblies

What4size4air4duct4is4required4to4move4air4at430004cfm4at46304fpm4if4using4a4r
ound4duct
A)430"
B)418"
C)425"
D)420"4-4answer-A)430"

The4exhaust4ventilation4system4of4a4machinery4room4with4a4refrigeration4system4
must4have4its4own4emergency4shut4off4switch4where?
A)4by4the4exit4inside4the4room

, B)4by4the4exit4outside4the4room
C)4inside4the4room4within424feet4of4the4a/c4emergency4shut4off
D)4outside4the4room4within424feet4of4the4a/c4emergency4shut4off4-4answer-
D)4outside4the4room4within424feet4of4the4a/c4emergency4shut4off

What4is4the4tonnage4rating4for4high4pressure4packaged4water4cooled4centrifugal4
a/c4compressors?
A)4254to420004tons
B)4104to410004tons
C)4854to450004tons
D)4104to45004tons4-4answer-C)4854to450004tons

In4a4chiller4system4low4pressure4liquid4refrigeration4is4located4in4the?
A)4condenser
B)4evaporator
C)4compressor
D)4economizer4-4answer-A)4condenser

In4a4two4way4valve,4complete4turning4of4the4valve4counterclockwise4produces4wh
at4effect?
A)4stops4refrigerant4flow
B)4allows4removal4of4device
C)4shuts4off4access4port
D)4redirects4refrigerant4flow4completely4-4answer-C)4shuts4off4access4port

a4bourbon4tube4responds4to?
A)4humidity
B)4pressure
C)4relative4humidity
D)4temperature4-4answer-B)4pressure

Why4do4some4filter4dryers4have4access4ports?
A)4code4requirement
B)4allow4easy4serviceability4of4the4A/C4unit
C)4measure4pressure4drop4across4filter
D)4ease4of4construction4-4answer-C)4measure4pressure4drop4across4filter

Defrost4sensors4are4placed4where4in4a4hermetic4compressor4refrigerant4system?
A)4on4the4liquid4line
B)4on4the4suction4line
C)4where4the4ice4last4forms
D)4where4the4ice4first4forms4-4answer-A)4on4the4liquid4line

The4refrigerant4condensing4system4with4group4I4refrigerant4shall4be4enclosed4in4a
4machinery4room4if4the4horsepower4rating4on4the4condenser4exceeds4
A)4100