Outdoor reset of hot water temperature for heating gives:

hottest water during the coldest weather

what is the meaning of "closed transition starting?"

the motor is not disconnected from the line during transition

Which of the following is NOT acceptable when interacting with the customer?

Complaining about your controntracter

Why are the frames of electrical devices grounded?

to maintain the frame at zero potential to ground

why is a surge suppressor used on a contact coil?

to prevent damage to the control circuit

Which of he following actions is NOT correct when working with an oxy-acetylene torch set?

Use grease or oil on the hose and regulator threaded connections

why is a surge suppresor used in a contactor coil?

to prevent control power voltage drop during starting

It is found that the voltage on the TSTAT terminals R-Y1 is 0 volts with 24 volts on R-C. this indicates...

The TSTAT is calling for cooling

After opening the disconnect, a service technician must first

Inspect & test all equip, assume energized until verified dead

the 3 pressures that operate the TXV are bulb, spring, and evaporator pressure

bulb opens, spring closes, evap closes valve

What is the definition of “de-minimus”?

small amount relative to the total charge

When recovering "bad" R-12, how should it be stored?

in a recovery cylinder for contaminated refrigerant

Which of the following is true of a dirty and unkempt service van?

It shows your professional character is messy and sloppy

which is acceptable when replacing defective circuit boards?

ground yourself before removing the new board from its packaging

As compared to across-the-line starters, reduced voltage starters reduce _______?

current inrush to the motor during starting

contacting a manufacturer regarding parts for a RTU, what is the most important information you can give them?

model number and serial number of the unit

which is the best way to "drive" refrigerant from a cylinder into a unit being charged?

heat the cylinder by wrapping it in a specially built electric heater

studbud

HVAC Star exam part 1

100 termsStudBud Administration57 plays

Imported from external platform

Flashcards100 cardsFPractice quizPHost liveL

Questions 100

Answers

1
Most appliance gas valves require the inlet natural gas pressure NOT to exceed which of the following?
7 psi
7" W.C.
3.5” W.C.
3.5 psi
2
How would terminals "D" be labeled?
T1, T2,T3
L1, L2, L3
Load 1, Load 2, Load 3
C1, C2, C3
3
Outdoor reset of hot water temperature for heating gives:
night setback
hottest water during the coldest weather
hottest water only in the morning
hottest water during milder weather
4
For what purpose is a cold trap installed in series with a vacuum pump?
it traps moisture
it speeds up the evacuation
you don’t have to shut the pump down to change the oil
it traps excess oil
5
why should low water cut off controls on a steam boiler be blown down routinely?
prevents sediment acumulation
keeps the pipes clean
keeps the contacts clean
required by code
6
what is the meaning of "closed transition starting?"
the contactors stay closed during transition
the motor is not disconnected from the line during transition
the contactors coil stays energized during transition
the motor is disconnected from the line during transition
7
Which of the following is the most common instrument to verify the flow of a pump?
current transformer on the pump
flow switch
sail switch
pump interlock
8
when troubleshooting a control board you find there is no control power. which of the following do you first check?
control fuse
main fuse
main power
control power
9
which of the following is not a digital input
modulating chilled water valve
fan proof
fan proof
VFD start
10
Which of the following is NOT acceptable when interacting with the customer?
Keeping the conversation on topic and not rambling on
Being clean and presentable
Telling the customer the condition of their equipment
Complaining about your controntracter
11
Why are the frames of electrical devices grounded?
to maintain the frame at zero potential to ground
to improve electrical operating efficiency
to blow a fuse in the event of an overload
to insure safe power restoration after an outage
12
why is a surge suppressor used on a contact coil?
to smooth circuit wave forms
to prevent damage when contacts close
for a faster and smoother start
to prevent damage to the control circuit
13
on a 480v 3ph starter, approx what voltage should you have at the motor?
+/- 10% of motor rated voltage
+/- 7% of motor rated voltage
+/- 15% of motor rated voltage
+/- 5% of motor rated voltage
14
A ton of refrigeration is equal to all EXCEPT which of the following
288,000 btu/24 hours
12,000 btu/minute
12,000 btu/hour
200 btu/minute
15
Which of the following governmant agencies regulates the certication of regrigerant cylinders?
DEA
FAA
DOT
OSHA
16
What results when you reduce water flow to a water cooled condenser?
discharge temps go down
head pressure lowers
head pressure rises
capacity is increased
17
Which of he following actions is NOT correct when working with an oxy-acetylene torch set?
Never open the acetylene cylinder valve more than 1-1/4 turns
Store oxygen cylinders away from combustibles.
Never exceed 15 psi on the acetylene regulator
Use grease or oil on the hose and regulator threaded connections
18
why is a surge suppresor used in a contactor coil?
to help protect the motor
to act as a filter for control voltage to the coil
to prevent control power voltage drop during starting
to act as a filter for the line voltage to the motor
19
What does CPR stand for?
Carrier Programmable Rectier
Copeland Pneumatic Relay
Cardio Pulmonary Resuscitation
Certied Personnel Response
20
what is an acceptable replacement without changing oils for HCFC-22?
R-123yf
R-407c
R-410a
R-134a
21
a constant _____ is maintained by the TXV
superheat
pressure drop
subcooling
amp draw
22
which is not an acceptable way for capacity control on a cooling tower?
dampers on fan
VFD on fan motor
adjust sump temp setpoint
variable pitch fan blades
23
It is found that the voltage on the TSTAT terminals R-Y1 is 0 volts with 24 volts on R-C. this indicates...
there is a problem with the control transformer
The TSTAT is calling for cooling
the thermostat is malfunctioning
the thermostat is not calling for cooling
24
in order for oil to be burned, it must be atomized at what nozzle pressure?
50 PSI
10 PSI
100 PSI
500 PSI
25
which of these devices is needed for proper operation of a system with VAV control?
high limit
CO2 sensor
building exhaust fan
duct static pressure sensor
26
which of the following is not an acceptable method of capacity control for a centrifugal compressor
inlet vanes
hot gas bypass
unloaders
VFD
27
After opening the disconnect, a service technician must first
Ask someone nearby what is the condition of the equipment
Work only on equipment that is marked or tagged "dead"
Work only on equipment that the supervisor says is dead
Inspect & test all equip, assume energized until verified dead
28
which of the following devices changes energy from one from to another
transformer
transducer
thermistor
none of these
29
Which Federal agency is responsible for personal safety?
NFPA
DOT
DOL
OSHA
30
the 3 pressures that operate the TXV are bulb, spring, and evaporator pressure
bulb closes, spring closes, evaporator opens the valve
bulb opens, spring closes, evap closes valve
bulb closes, spring opens, evaporator opens the valve
bulb opens, spring closes, evaporator opens the valve
31
Which type of ignition system uses a pilot flame?
direct spark
oil burner
standing pilot
hot surface
32
when calibrating a velocity controller with a magnihelic, which ports are connected on the magnehelic to the flow ring
high port only
calibrate high then low separately
low port only
high and low ports
33
When calculating superheat for a HFC refrigerant with a large temp glide, what method should be followed
use the bubble point temperature
use the saturation temperature
use the bubble or dew point temperature
use the dew point temperature
34
When handling refrigerants, what protection is required for your eyes?
safety glasses
face shield
face shield and safety glasses
chemical splash goggles
35
after Jan 2019, what is the acceptable annual leak rate percentage of a comfort cooling system?
35
30
10
20
36
what is the proper way to check the rotation of a screw compressor
phase checker
amp draw
bump it over and check rotation
visual
37
What is the definition of “de-minimus”?
small amount relative to the total charge
one half of the total charge
one quarter of the total charge
enough liquid to purge the hoses
38
When recovering "bad" R-12, how should it be stored?
in a recovery cylinder for contaminated refrigerant
in your normal use recovery cylinder
doesnt matter as it will be reclaimed
vent to atmosphere
39
the operation of the flame rectification combustion control system is based on which of the following?
flame is sensed by exhaust temperature
flame conducts electricity
flame is sensed by the photo eye
flame is sensed by a thermocouple
40
Which of the following is true of a dirty and unkempt service van?
It shows your contractor should pay you to clean and wax your van
It means you are a mechanical genius
It shows your professional character is messy and sloppy
It doesn’t matter at all what your van looks like
41
which is acceptable when replacing defective circuit boards?
pull wires off the old board after installing new one, then wire new one
use a board from another unit to make sure it is defective
ground yourself before removing the new board from its packaging
replace all the board to save time
42
As compared to across-the-line starters, reduced voltage starters reduce _______?
control power voltage
current inrush to the motor during starting
line voltage
running current
43
contactors contain which to sets of contacts?
stationary and removable
spring loaded and stationary
copper and silver
steel and copper
44
contacting a manufacturer regarding parts for a RTU, what is the most important information you can give them?
unit tonnage
circuit ampacity of the unit
voltage of the unit
model number and serial number of the unit
45
what is the max safe amperage draw of the secondary winding of a 40va transformer with 230v primary and 24v secondary
5.75 amps
0.6 amps
1.66 amps
0.173 amps
46
which is the best way to "drive" refrigerant from a cylinder into a unit being charged?
Heat the cylinder with a heat lamp.
Heat the cylinder with a torch.
Heat the cylinder by immersing it in a tub of warm water.
heat the cylinder by wrapping it in a specially built electric heater
47
Electric heaters are ussually composed of which of the following?
resistive heating elements
electronic heating elements
capacitive heating elements
inductive heating elements
48
A recovery tank with a DOT service rating of ______psig is required for R-410a.
350
400
300
200
49
Which of the following oils is the most hygroscopic?
mineral
PAG
alkylbenzine
POE
50
How many Btu/h will be provided by one watt of electrical power?
3.141
3.412
31.41
34.12
51
When the motor of a two wire spring return actuator is operating, the spring is ________
a safety
winding up as is opens
winding up as it closes
assisting the opening of the actuator
52
Which one of these devices does NOT sense temperature
thermostat
thermistor
transducer
klixon
53
the boiling point of refrigerant in the condenser is the same as which of these?
discharge superheat
condenser superheat
condenser subcooling
condenser saturation temp
54
Incorrect rotation of a scroll compressor will cause which of these events?
the compressor will not compress.
the compressor will stop on motor overload.
the compressor will make excessive noise
all of these
55
the oil pressure safety control operates on which two pressures in the refrigeration system
discharge pressure minus suction pressure
oil discharge pressure minus suction pressure
oil pump discharge pressure plus suction pressure
discharge pressure plus suction pressure
56
what is the fastest way to recover refrigerant?
pump
push/pull method
vapor
liquid
57
what is the purpose of pulling a system into a proper vacuum?
dehydrates the system and removes non condensables
it removes the water from the system
it allows you to suck in the refrigerant
it removes excess oil from the system
58
which is the acceptable voltage drop across an energized contactor
< 2 volts
< 1 volt
< 0.5 volt
< 5 volts
59
how does one reverse the rotation of a 3 phase motor
change the phasing from ABC to ACB
reverse the rotor
call the electrician
get a new motor
60
what is the only acceptable refrigerant to be used as a trace gas when checking for leaks?
R-134a
R-12
R-22
R-410a
61
When replacing the element on an electric heater, the technician should verify the _______.
length and wattage of the heater
manufactures name
length of the heater
heater amp draw
62
what is the device used in electrical circuits to prevent damage from current overloads
transister
fuse
bimetal switch
diode
63
What is an acceptable vent material for condensing boilers?
sheet metal
carbon steel pipe
B vent
PVC pipe
64
when charging a R-410a system, refrigerant should be charged as a
liquid
Gas
65
How many BTU’s are absorbed when 1LB of water at 212F is changed to 1LB of steam at 212F?
144
1000
500
970
66
What is the last thing you should do before leaving the jobsite?
Getting your paperwork signed by the customer
Give your keys back to the customer
Clean and wax the equipment
Walk through and make sure eveything is running.
67
the symbol below would be used to indicate a ______ switch?
pressure actuated
spring loaded
temp actuated
flow
68
you could use which of these devices to protect a large condenser against excessive pressures?
burst disc
one time relief valve
thermal overload
spring loaded relief valve
69
if mechanical refrigeration and a cooling coil are used for dehumidification, this may be required for proper operation.
condensate
oil
dessicant
reheat
70
an unprepaired refrigerant leak will cause which of the following conditions?
capacity loss and increased compressor motor amp draw
capacity loss and elevated suction pressure
capacity loss and elevated head pressure
capacity loss and compressor motor overheating
71
A dual-element fuse has:
thermal cutout only
can carry locked-rotor amps of a motor but protects against short circuits
thermal cutout and a normal fuse link
two normal one-time fuse links
72
what is the purpose of the jump frequency range (skip frequency range) on a VFD
skips output frequency to reduce harmonics
Skips output frequency to prevent overheating
Skips output frequency to prevent over amping
Skips output frequency to prevent voltage spikes
73
Which of the following is not used to size gas regulators
volume
inlet pressure
pipe size
type of ignition system
74
Outdoor reset of hot water temp for heating provides for which of these options?
quick changover between heating and cooling
hottest water on the coldest days
better control but lower energy savings
hottest water on the warmest days
75
in an air cooled system with capacity control, compressor unloading will cause _________
suction pressure to rise, discharge pressure to drop
suction pressure to drop, discharge pressure to drop
suction pressure to drop, discharge pressure to rise
suction pressure to rise, discharge pressure to rise
76
to reduce turbulence on the suction side of a pump, a straight pipe equal to _____ diameters of the pipe can be used
5
10
15
2.5
77
Which of the following is NOT a required part of the work order?
Listing all parts and materials used
Getting the customers signature
Having a detailed description of work performed listed
Adding your contractors mark up for parts
78
what is the meaning of the symbol shown here?
normally closed, open on rise in pressure
normally closed, open on drop in pressure
normaly closed, open on temperature increase
normally closed, open on drop in temperature
79
a 3 phase motor to be used with a part winding starter must have
one set of windings on a delta con
two sets of delta wound windings wired in series
2 sets of star wound windings wired in parallel
one set of windings on a star configuration
80
which of the following tools is used to measure the relative humidity of the air
sling psychrometer
magnehelic
pitot tube
DMM
81
How would terminals "A" be labeled?
L1, L2, L3
Load 1, Load 2, Load 3
C1, C2, C3
T1, T2,T3
82
how should safety controls be wired?
in series
combination series and parallel
directly to the thermostat
in parallel
83
Which of these should be worn to protect the eyes when handling refrigerants?
#4 brazing lens
contact lense
eye protection is NOT required
chemical/splash goggles
84
How can you make an amp meter measure low current levels?
use a megger
use an inline meter
wrap the wire being tested multiple times around the amp clamp
set your meter to a lower scale
85
suction gas temperature minus saturated suction temp is equal to which of the following?
evaporator pressure drop
system superheat
condenser subcooling
evaporator superheat
86
which one of these control modes does not provide modulating control?
Proportional
Derivative
Binary
Integral
87
which of these is true of 3 phase AC?
the phases are out by 90 degrees
the phases are out by 60 degrees
the phases are out by 120 degress
the phases are out by 60 degrees
88
the compression ratio in a system can be determined by:
subtract suction PSIA from discharge PSIA and divide by 12,000 btu/hr
multiplying discharge gage pressure by suction gage pressure
dividing discharge pressure absolute by suction pressure absolute
dividing suction pressure absolute by discharge pressure absolute
89
which of the folliwing is a disadvantage of a variable refrigerant flow (VRF) system?
zone control
energy savings
heat recovery
future expansion
90
A cylinder tank with a service rating of DOT ____psig is required for R410a.
200
300
400
100
91
A hermetic compressor internal overload senses which of the following?
amp draw
compression ratio
stator winding temp
oil temperature
92
When conducting certication of lockout procedures, which of the following observations must be first.
PPE available
disconnect locked out by all people working on the unit
safe weather conditions
verication of the power actually being disconnected
93
Cleaning refrigerants to ARI 700 standards is called:
recovery
reclaiming
recycling
reusing
94
the "megger" is an instrument which, when used in conjunction with motor testing can tell _______
if the motor is about to fail
the integrity of the windings and conductors insulation
how many ohms of resistance the motor has
if the contactor contacts have too much resistance
95
what happens if dirty filters in an air conditioning system reduce the airflow across the evaporator?
suction pressure drops, capacity rises
suction pressure rises, capacity rises
suction pressure rises, capacity drops
suction pressur drops, capacity drops
96
Which organization or department enforces the regulations of The Clean Air Act?
Department of Commerce
DOT
EEDC
EPA
97
a pnuematic Tstat must be selected for a NC chilled water valve. which of the following would be the correct Tstat?
dual input reverse acting
night setback reverse acting
direct acting
reverse acting
98
the symbol shown here would be used to indicate which type of switch?
normaly open close on drop in pressure
normaly open close on rise in temperature
normaly open close on drop in temperature
normaly open close on rise in pressure
99
what type of guage reads pressure both above and below atmospheric pressure?
compound
micron
bellows
bourdon tube
100
How should the skin that comes in contact with liquid refrigerant be treated?
chemical burns
electrical burns
heat burns
frostbite

HVAC Star exam part 1 Flashcards | StudBud