NATE Exam: Air Conditioning and Heat
Pumps
Which of the following factors affects a customer's level of
comfort?
a. Air
movement
b.
Humidity
c.
Temperature
d. All of the above correct answers d (All of the above: air movement,
humidity,
temperatur
e)
A cooling load calculation estimates the sensible heat gain of a structure. The
maximum
sensible capacity of a cooling-only system should be within % of this
calculated
value
.
a.
±10%
b.
+10%
c.
+15%
d. +30% correct answers c
(+15%)
The maximum sensible cooling capacity of a heat pump should be within
calculated sensible heat gain of a structure with a large % of
the
heating load.
a.
±10%
b.
+15%
c. -
d. +25% correct answers d
25%
(+25%)
The combined output of a heat pump and its auxiliary heat should not
exceed theheat loss of a home by more than
calculated
%.
a.
b.
10%
15%
c.
20%
d. 25% correct answers b
(15%)
What amount of auxiliary electric heat is needed when the output of a heat
pump on
design a equals 18,800 Btuh and the heat loss of a home is
day
29,700 Btuh?
a. 2.1
b. 3.2
kWh
kWh
c. 5.0
kWh
,d. 10.9
kWh
Note: 3,413 Btu/kW correct answers b (3.2
kWh)
The three processes that transfer heat energy are conduction, convection,
and
.a.
concentration
b.
radiation
c.
refraction
d. static pressure correct answers b
(radiation)
Heat transfer that occurs when substances of different temperatures are in
contact
each withis called
other
.
a.
concentration
b.
conduction
c.
convection
d. radiation correct answers b
(conduction)
What effect does raising the pressure in a sealed system have on
refrigerant?
a. It becomes more difficult to subcool the liquid
refrigerant
b. It becomes more difficult to superheat the
refrigerant
c. vapor boiling point
The refrigerant's
decreases
d. The refrigerant's boiling point increases correct answers d (The
refrigerant's boiling
point
increases)
What is the primary danger to people near an accidental refrigerant
release or spill?
a. Blurred vision caused by the refrigerant vapor coming in contact
with
b. Changes
the eyes in weather patterns caused by global
warming
c. Damage to the food chain caused by decreased ozone levels in the
stratosphere
d. Suffocation caused by the heavier refrigerant displacing oxygen in the
air correct
answers d (Suffocation caused by the heavier refrigerant displacing oxygen
in the air)
The maximum temperature at which refrigerant may be stored is °F
when the is no more than % full of liquid by
container
volume.
a. 120°F,
60%
b. 125°F,
60%
c. 125°F,
80%
d. 135°F, 80% correct answers c (125°F,
80%)
Boiling of the refrigerant occurs in which system
component?
a.
Compressor
, b.
Condenser
c.
Evaporator
d. Metering device correct answers c
(Evaporator)
Why is superheat necessary in a system that utilizes hermetic
compressors?
a. It ensures that dry vapor reaches the compressor so that mechanical
damage does
not
occur
b. It increases system
capacity
c. It prevents liquid refrigerant from gassing the
metering
d. device
Superheat is necessary only when open compressors are being used
correct
answers a (It ensures that dry vapor reaches the compressor so that
mechanical
damage does not
occur)
When the heat load on an evaporator increases, what is the effect on
the system?
a. Suction pressure decreases and discharge pressure
increases
b. Suction pressure increases and discharge pressure
decreases
c. Suction pressure and discharge pressure both
decrease
d. Suction pressure and discharge pressure both increase correct answers
d (Suctionand discharge pressure both
pressure
increase)
What type of energy is transferred when work is done in the
condenser?
a. Latent heat
energy
b. Sensible heat
energy
c. Both latent and sensible heat
energy
d. Neither latent nor sensible heat energy correct answers c (Both latent
and sensible
heat
energy)
What is the primary function performed by a thermal
expansion valve?
a. It maintains the correct superheat in the hot vapor leaving the
compressor
b. It maintains the correct superheat in the suction vapor leaving the
evaporator
c. It maintains the proper subcooling level in the liquid
refrigerant
d. It prevents flash vapor bubbles from developing in refrigerant entering the
correct answers b (It maintains the correct superheat in the suction vapor
evaporator
leaving the
evaporato
r)
Which component pumps refrigerant through the system and raises
the vapor
temperatur
e?
a.
Accumulator
b.
Compressor
c.
Condenser
d. Evaporator correct answers b
(Compressor)
Pumps
Which of the following factors affects a customer's level of
comfort?
a. Air
movement
b.
Humidity
c.
Temperature
d. All of the above correct answers d (All of the above: air movement,
humidity,
temperatur
e)
A cooling load calculation estimates the sensible heat gain of a structure. The
maximum
sensible capacity of a cooling-only system should be within % of this
calculated
value
.
a.
±10%
b.
+10%
c.
+15%
d. +30% correct answers c
(+15%)
The maximum sensible cooling capacity of a heat pump should be within
calculated sensible heat gain of a structure with a large % of
the
heating load.
a.
±10%
b.
+15%
c. -
d. +25% correct answers d
25%
(+25%)
The combined output of a heat pump and its auxiliary heat should not
exceed theheat loss of a home by more than
calculated
%.
a.
b.
10%
15%
c.
20%
d. 25% correct answers b
(15%)
What amount of auxiliary electric heat is needed when the output of a heat
pump on
design a equals 18,800 Btuh and the heat loss of a home is
day
29,700 Btuh?
a. 2.1
b. 3.2
kWh
kWh
c. 5.0
kWh
,d. 10.9
kWh
Note: 3,413 Btu/kW correct answers b (3.2
kWh)
The three processes that transfer heat energy are conduction, convection,
and
.a.
concentration
b.
radiation
c.
refraction
d. static pressure correct answers b
(radiation)
Heat transfer that occurs when substances of different temperatures are in
contact
each withis called
other
.
a.
concentration
b.
conduction
c.
convection
d. radiation correct answers b
(conduction)
What effect does raising the pressure in a sealed system have on
refrigerant?
a. It becomes more difficult to subcool the liquid
refrigerant
b. It becomes more difficult to superheat the
refrigerant
c. vapor boiling point
The refrigerant's
decreases
d. The refrigerant's boiling point increases correct answers d (The
refrigerant's boiling
point
increases)
What is the primary danger to people near an accidental refrigerant
release or spill?
a. Blurred vision caused by the refrigerant vapor coming in contact
with
b. Changes
the eyes in weather patterns caused by global
warming
c. Damage to the food chain caused by decreased ozone levels in the
stratosphere
d. Suffocation caused by the heavier refrigerant displacing oxygen in the
air correct
answers d (Suffocation caused by the heavier refrigerant displacing oxygen
in the air)
The maximum temperature at which refrigerant may be stored is °F
when the is no more than % full of liquid by
container
volume.
a. 120°F,
60%
b. 125°F,
60%
c. 125°F,
80%
d. 135°F, 80% correct answers c (125°F,
80%)
Boiling of the refrigerant occurs in which system
component?
a.
Compressor
, b.
Condenser
c.
Evaporator
d. Metering device correct answers c
(Evaporator)
Why is superheat necessary in a system that utilizes hermetic
compressors?
a. It ensures that dry vapor reaches the compressor so that mechanical
damage does
not
occur
b. It increases system
capacity
c. It prevents liquid refrigerant from gassing the
metering
d. device
Superheat is necessary only when open compressors are being used
correct
answers a (It ensures that dry vapor reaches the compressor so that
mechanical
damage does not
occur)
When the heat load on an evaporator increases, what is the effect on
the system?
a. Suction pressure decreases and discharge pressure
increases
b. Suction pressure increases and discharge pressure
decreases
c. Suction pressure and discharge pressure both
decrease
d. Suction pressure and discharge pressure both increase correct answers
d (Suctionand discharge pressure both
pressure
increase)
What type of energy is transferred when work is done in the
condenser?
a. Latent heat
energy
b. Sensible heat
energy
c. Both latent and sensible heat
energy
d. Neither latent nor sensible heat energy correct answers c (Both latent
and sensible
heat
energy)
What is the primary function performed by a thermal
expansion valve?
a. It maintains the correct superheat in the hot vapor leaving the
compressor
b. It maintains the correct superheat in the suction vapor leaving the
evaporator
c. It maintains the proper subcooling level in the liquid
refrigerant
d. It prevents flash vapor bubbles from developing in refrigerant entering the
correct answers b (It maintains the correct superheat in the suction vapor
evaporator
leaving the
evaporato
r)
Which component pumps refrigerant through the system and raises
the vapor
temperatur
e?
a.
Accumulator
b.
Compressor
c.
Condenser
d. Evaporator correct answers b
(Compressor)
