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NATE Heat Pump 2023 [Part 1] Flashcards | StudBud
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NATE Heat Pump 2023 [Part 1]
NATE Heat Pump 2023 [Part 1]
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Answers
1
Where are low pressure limit controls installed?
On the shorter sides of rectangular duct
With suction vapor drawn from
The forward curve centrigual fan.
The suction line of a heat pump.
2
where does refrigerant boil
in the reciever
in the condenser
in the evaporator
undersized vapor line
3
where should you check voltage input to a compressor
in the evaporator
load side of the contactor
flooding of the indoor coil
the indoor coil and the compressor
4
During the heating mode, the refrigerant in the indoor coil is under.
A vacuum
Low pressure
High pressure
Atmospheric pressure
5
At what temperature is an outdoor ambient themostat normally set?
15° above the inital balance point
Slightly above the intial balance
The same as the indoor thermostat
At 32°F
6
What is defined as two or more switch contacts connected in a circuit, or set of circuits, to control a load.
Coil td.
240V single phase
Control string
Curb gasket
7
A resitance reading of infinity across the "R" terminal and "S" terminal of a compressor motor indicates a(n) ______.
tripped internal overload
fan switch
open motor winding
shorted
8
the unit has piston metering device and the superheat is 55 degrees whats wrong?
damaged
coil td
overcharged
undercharged
9
Refer to the image.
1.12 amps
1.7 amps
1.3 amps
25 amps
10
When must the installer must be certain to plumb the cabinet so its sides are vertical?
When changing out an evaporator coil.
Two speed compressor. Two stage thermostat.
Increases rigidity and reduces vibration.
When lines are routed inside a wall.
11
During the deforst cycle, the outdoor fan is usualy ____.
Turned off
Run in reverse
Set to high speed
Set to low speed
12
what are disc type temperature limit controls used for
the foward curve centrifugal fan
the indoor coil and compressor
work is being done on wet surfaces
protect auxiliary heat from overheating
13
100,000 BTUH output furnace; Return air temp is 65°F; Supply air temp is 135°F; What is the CFM?
1313 CFM
29,177 BTU/H
1323 CFM
1423 CFM
14
During the defrost cycle, the system switches to the ____ mode.
Emergancy heating
Cooling
Pump down
Heating
15
Do electric air cleaners remove odors?
No
Yes
16
what happens if you increase suction pressure on a recipricating compressor
the refrigerants boiling point increases
the indoor coil and the compressor
replace the diffuser
the capacity would decrease
17
What condition can cause a reducion from design capacity in a heat pump?
Two speed compressor. Two stage thermostat.
Undersized vapor line.
Inefficient voltage or current
Compressor discharge line.
18
What is the minimum circuit amp listed on a units' data plate is used to determine?
225°F
The max fuse or circuit breaker size.
The indoor coil and the compressor.
Heating control circuit amperage draw.
19
What factors affects a customer's level of comfort?
Air movement humidity temperature
System td, drop, and static pressure
Relative humidity is high.
Lower than normal suction pressure
20
which of the following should be used to leak-test refrigerant tubing
pipe dope
flash gas
dry nitrogen
prevent oxidation
21
R410A heat pump operating in the heating mode has a SP 50 psig & HP 285 psig compression ratio
3.2:1
5.7:1
4.6:1
7.7:1
22
Work done on the refrigerant in the condenser is transferred as ____.
Motor windings could become damaged.
Both sensible and latent heat.
All connections iner and oyter layers.
The refrigerants boiling point increases.
23
Heat Pump unit; 1st and 2ns stage appear to be calling, compressor runs but not electric heater, what is the problem?
While it is cool
Flow of air is insufficient
Second stage is open
Dry nitrogen
24
Refer to the image.
Control String
Curb Gasket
Coil TD
Bulb Pressure
25
Voltage across a closed contact in a 24V control circuit could indicate what?
Excessive suppler air velocities
Pitted or dirty contacts
5000V
Control string
26
What is sensible heat ratio?
sensible removed ÷ total heat removed
power off, fuse removed
motor windings could become damaged
both latent and sensible heat
27
What will you get when a capillary tube is overcharged?
low superheat and high sub cooling
both latent and sensible heat
A triangular or knife-edge file
voltage check of the supply line
28
A system should operate at least------before heat measurements taken
15 minutes
20minutes
5minutes
3minutes
29
how are hermetic compressors cooled
with air drawn around compressor shell by the fan
with suction vapor drawn from evaporator
the suction line of a heat pump.
with a combination of air and water
30
inadequate heating can be caused by what?
restriction in the liquid line
compressor discharge line
inefficient voltage or current
dirty or clogged air filter
31
What is the best method of repair when a residential supply diffuser is nosiy because of a loose vane?
The indoor coil and the compressor
240V single phase
Use vibration isolators
Replace the diffuser
32
if a solenoid is vibrating or chattering what is the cause
inefficient voltage or current
the suction line of a heat pump
second stage is open
airflow will be increased
33
what kind of energy does condenser remove from refrigerant
excessive supply air velocities
increase rigidity and reduces vibration
system td,drop and static pressure
sensible heat and latent heat
34
When is crackcase heat most needed?
When the compressor is off.
When lines are routed inside a wall.
Sensible removed ÷ total heat removed
In the evaporator.
35
what happens when you run a hermetic compressor in a vacuum
restriction in liquid line
both latent and sensible heat
undersized vapor line
motor windings become damaged
36
a good fuse will yield a reading of-----on an ohm meter
-10 ohms
-5 ohms
0 ohms
5ohms
37
what is the heating capacity in BTUH?
30,177 btu/h
29,277 btu/h
29,187 btu/h
29,177 btu/h
38
whats the primary purpose using flux when brazing copper to brass
prevent oxidation
enhance bond strength
dry nitrogen
prevent tarnish
39
What is the recommened CFM across the evaporator coil of a heat pump?
600 to 700 CFM
400 to 450 CFM
150 to 225 CFM
200 to 300 CFM
40
What is the recommended face velocity for air leaving a supply register?
699 ft/min
700 ft/min
450 ft/min
695 ft/min
41
When should a technician test a hermetic compressor for a permanently open internal overload protector?
Undersized vapor line.
An open check valve
While its cool.
Control string
42
a restricted filter drier can cause what?
systemtd,drop and static pressure
lower than normal suction pressure
bulb pressure
both latent and sensible heat
43
what is a necessary check to properly set a heat anticipator
to minimize refrigerant pressure drop
restriction in the liquid line
the max fuse or circuit breaker size
heating control circuit amperage draw
44
what is the absolute pressure at sea level if a gauge reads35psig
49.7psia
49.93psia
48.7psia
49.35psia
45
manufactures recommend as the most acceptable method attaching line sets to a ahu
utilizing brazing allow
replace the diffuser
1323 cfm
use vibration isolators
46
When is condensation on vapor lines a concern?
The max fuse or circuit breaker size.
When lines are routed inside a wall.
Excessive supply air velocities.
Increases rigidity and reduces vibration.
47
What is the effect on supply airflow when static pressure on the return is reduced.
airflow will be increaseed
dry nitrogen
airflow will be the same
curb gasket
48
Your inspections find a liquid line that has condensation on it. What is the most likely to cause this?
The indoor coil and the compressor
EPA Section 608 Certification
Volatage check of the supply line
Restricition on the liquid line.
49
a resistance reading of 0Ω across a coil indicates the coil is?
closed
shorted
grounded
open motor winding
50
on a r-22 system ,line diameters and length are specified for vapor drop that dont exceed
11-12psi or 6fareheight
6-7psi or 6 farenheight
1-4psi or 6farenheight
6-7psi or 106farenheight
51
What ae the ttwo generally used methods for changing capacity on demand in a heat pump
Two speed compessor. Two stage thermostat.
Brazing allowed with approved flux
Undersized vapor line
System td, drop, and static pressure
52
In order to determie a heat pumps balance point, you must first calculate:
The EER of the unit during a praticular season
The brand name of the compressor
The buildings heat load
The consumption of kilowatts at 32 degrees
53
voltage supplied to a motor may vary from the rated voltage by--%
while its cool
d(+10%-10%
dry nitrogen
prevent oxidation
54
Liquid line filter/driers that are used on heat pump systems.
Are designed with 4 connectors for connection to a 4 way valve
Must be installed in series with check valves
Must be installed in conjuction with bi-flow check valves
Must be bi-fow design if used without check valves
55
what type of energy is transfered when work is done in the condenser?
motor windings could be damaged
both latent and sensible heat
both sensible and latent heat
increases rigidity and reduces vibration
56
What is the most commonly used type of fan in residential systems?
The forward curve centrifugal fan.
Flooding of the indoor coil.
The refrigerants boiling point increases
An indefinite length of time.
57
What effect does raising the presssure in a sealed system effect the refrigerant?
The refrigerants boiling point increases.
Airflow will be increased.
Sensible heat and latent heat
The capacity would decrease.
58
Refrigerant flow through the compressor.
Is normal in the cooling mode & reveresed in the heat mode
Is the same regardless of the operating mode
Is normal in the heat mode & reversed in the cooling mode
Can be either direction depending on operating mode
59
How many CFM per ton of cooling?
400 CFM per ton
1.67 amps
700 ft/min
800 CFM per ton
60
which of the following brazing materials is for use on a refrigerant piping
225f
solder
dry nitrogen
brazing alloy with flux
61
What is the flow rate per ton of cooling wter source heatpumps operateing in closed loop system
3.0 gpm per ton
2.5gpm per ton
.5 oz per year
1.5 gpm per ton
62
Hard-start kits are often needed on _____.
Sensible heat and latent heat
Prevent oxidation
Reciprocating compressors used with TEVs
Scroll compressor used with Tevs
63
The maximum temperature at which refrigerant may be stored is ______ when the container is no more than _______% full
130F°, 80%
125F°, 80%
20 minutes
125F°, 70%
64
what doe this tell you with testing a run capacitor with analog meter on ohms needle swings to 0 and slowly rises
use vibration isolators
the capacitor charges and discharges
at load side of the contactor
65
What is the effect on supply airflow when static pressure on the return is reduced?
Curb gasket
Aiflow will be increased
Dry nitrogen
Airflow will be essentially the same
66
a 24v transformer with 40va rating can safelyoperate with current of?
1.67 amps
0.83 amps
200amps
2.2 amps
67
What is a duct system that has a single trunk extending in one or two directions with many branch ducts?
Curb gasket
Extended plenum duct system
Radial duct system
Reducing trunk system
68
What tool should be used to shorten a capillary tube?
A triangular or knife-edge file
A pair of pliers with slide-cutter edges
A small tubing cutter
Any tubing cutter approved for use on refrigerant tubing
69
When the airflow through an electric heater is insufficient, the technician will observe _____.
Prevent oxidation
Fusible links glowing red or orange
Fan switch
Heater elements glowing red or orange
70
in order to troubleshoot a load controlled by a control string what should the tech check 1st?
based on the cooling mode
the indoor coil and compressor
proper voltage applied across the load
voltage check of the supply line
71
Where is a high pressure limit controll installed?
Compressor suction service valve.
Compressor discharge line
Condenser water supply line.
Undersized vapor line
72
What does a bright red or orange glow from the resitance element in a duct heater indiciate?
Flow of air is insufficient.
Supply wired are oversized.
Duct heaters are operating properly.
Line volatge is insufficient.
73
what is the purpose of a cross break on the flat sides of metal ductwork?
both latent and sensible heat
increases rigidity and reduces vibration
system TD,drop,and static pressure
prevent oxidation
74
when a heat load on an evaporator increases what is the effect on the system?
suction pressure and discharge pressure both increase
the fan stops to minimize defrost time
the refrigerants boiling point increases
lower than normal suction pressure
75
How many BTUH per ton of cooling
11,995 BTU/H per ton
12,000BTU/H per ton
400cfm per ton
225 F
76
refrigerants used in residential and commercial have shelf life of?
an indefinite length of time
an additional resistor
the foward curve centrifugal fan
an open check valve
77
any individual load on a 24v circuit should draw a current of?
1.67 amps
less than 1amp
.05oz per year
less than 4amps
78
what is the first check made for most electrical troubleshooting
restriction in the liquid line
compressor discharge line
voltage check of the supply line
undersized vapor line
79
When using a double element time-delay fuse with a 20 amp motor, what is the maximum fuze size that should be used?
25 amps
30 amps
20 amps
15 amps
80
Refer to the image.
10 lbs.
20 lbs.
8 lbs.
6 lbs.
81
which pressure in a TXV is the opening pressure
spring pressure
bulb pressure
curb gasket
evaporator pressure
82
in aHP circuit what is used to by-pass refrigerant flow around the metering device
an indefinite length of time
compressor discharge line
an additional resistor
an open check valve
83
Which component pumps refrigerant through the system and raises the vapor temperature?
Condenser
Compressor
Evaporator
Conduction
84
Which component is responsible for energizing auxiliary heat during the defrost cycle.
The defrost relay
The defrost time clock
Heater relay-1
The reversing valve relay
85
In the heat mode, the suction line entering the compressor contains.
Low pressure / high temperature liquid
High pressure / high temperature vapor
Low pressure / low temperature vapor
High pressure / low temperature liquid
86
What two checks typically made first on an electronic control?
Proper voltage applied across the load.
The max fuse or circuit breaker size.
The indoor coil and the compressor
Proper input voltage and proper output voltage.
87
what voltage is measured between any 2 hot legs on 3phase 240v panel
12v
240v
250v
140v
88
when wiring a 20amp fla motor whats the minimum fuse or breaker used
25amp
15amp
30amp
20amp
89
Temperature reading taken 6 in. from the compressor discharge line should never exceed.
175°F
150°F
112°F
225°F
90
when brazing what gas should be purged through the system to prevent oxidation
flash gas
a pipe dope
prevent oxidation
dry nitrogen
91
How should you test the continuity of a fuse?
Power off, fuse removed
Voltage check of the supply line
Incefficient voltage or current
Second stage is open
92
Refer to the image.
Use vibration isolators.
At the load side of the contactor.
The capacitor charges and discharges.
The refrigerants boiling point increases.
93
Accordingh to ohm's law, what will happen if voltage to a heat element is increased by 10%?
The BTUH output will increase by 5%
The current draw will increase by 15%
The current draw will increase by 35%
The current draw will increase by 10%
94
What is the common suction line on a heat pump connected to?
At the load side of the contactor
In the evaporator
Replace the diffuser
The indoor coil and the compressor.
95
how are heat pumps sized?
heating load
based on the cooling load
125°F, 80%
25 amps
96
what is the smallest leak that an electronic leak detector is capable sensing
125f,80%
3.0 gpm per ton
.025 oz per year
.5 oz per year
97
Why is it not always a good idea to immediately connect standard guages to a heat pump problem?
A guage manifold set is very expensive & should be used sparingly
Guages are never accurate
The charge is critical, sometimes to = 1/2 oz. Refrigerant
Most technicians cannot read a guage correctly
98
electronic air cleaners can operate with internal voltage as high as
30000v
5000v
2000v
4900v
99
In a heat pump circuit, what is used to bypass refrigerant flow around the metering device?
An additional resisitor
And indefinite lengh of time.
Compressor discharge line
An open check valve
100
why are there more circuits in aHP outdoor coil than in a/c outdoor coil?
heating control circuit amperage draw
to minimize refrigerant pressure drop
flow of air is insufficient
the refrigerants boiling point increases
