HVAC Exam 4 With All Correct & 100% Verified
Answers| Actual Complete Exam| Already Graded A+
What do technicians call the temperature at which water vapor begins to condense out of the air?
✔Correct Answer-B.ew point
What is the industry standard rate of through-the-evaporator airflow in CFM per ton for most air-
conditioning equipment ✔Correct Answer-B) 400 CFM per ton
______________is the measurement of the total heat content of the air expressed in BTU's per
pound of air. ✔Correct Answer-B) Enthalpy
If a technician wanted to accurately measure static pressure in a duct system, how would she place
the sensing probe of the magnehelic gauge? ✔Correct Answer-A) Place it perpendicular to airflow
___________________represents the amount of water vapor in the air compared to the amount of
water vapor the air can hold ✔Correct Answer-B) Relative humidity
What three environmental conditions have the most effect on comfort? ✔Correct Answer-B)
Temperature, humidity, and air movement
How does the human body expel heat if all the surrounding environment is above the body
temperature? ✔Correct Answer-A) Evaporation
Why does the air's relative humidity affect comfort? SKIP ✔Correct Answer-A) The relative
humidity affects how rapidly perspiration can evaporate
B) Human comfort is not affected by the relative humidity
C) Water molecules in the air act as thermal insulators
D) Water molecules in the air act as thermal conductors
How is the air volume affected by temperature? ✔Correct Answer-D) Air volume increases as the
air temperature increases
What type of measurement is a grain? ✔Correct Answer-A) A grain is a small measurement of
weight
What air property is measured in grains? ✔Correct Answer-C) Specific humidity
In general, which is denser humid air or dry air? ✔Correct Answer-C) Dry air
What is a wet bulb temperature reading? ✔Correct Answer-B) A temperature measured with a
water soaked wick around the thermometer bulb
Relative humidity is measured using ✔Correct Answer-A) Wet bulb and dry bulb temperature
readings
The temperature where water vapor can begin condensing out of the air is the ✔Correct Answer-
D) dew point
, What is specific humidity ✔Correct Answer-C) the weight of water in each pound of dry air,
measured in grains
A graphical representation of air properties is ✔Correct Answer-D) a psychrometric chart
SKIP What would the mixed air temperature be for a system with 30% outdoor air if the outdoor
temperature is 20°F and the return air temperature is 70°F? SKIP THIS ONE ✔Correct Answer-A) 0 3
x 20°F =6°F 0 7 x 70°F = 49°F 6°F + 49°F = 55°F mixed air
A Process that moves horizontally from left to right across a psychometric chart is ✔Correct
Answer-D) a sensible process
A Process that moves vertically up a psychometric chart is ✔Correct Answer-A) a latent process
The enthalpy lines are nearly parallel to the lines for ✔Correct Answer-A) wet bulb temperature
In the heating season, the comfort level can be improved at lower temperatures ✔Correct Answer-
B) By adding humidity to the air
In the cooling season, the comfort level can be improved at higher temperatures ✔Correct
Answer-D) By removing humidity and increasing air velocity
Physically active people feel more comfortable at ✔Correct Answer-A) Lower temperatures
The performance of an air conditioning system can be determined by measuring the airflow and
✔Correct Answer-C) The wet bulb temperature difference across the evaporator coil
While very effective at removing small contaminants, HEPA filters are not used in residential
applications because of what reason? ✔Correct Answer-They cause a high pressure drop in the
duct
_____________________use DC voltage to attract dust and contaminants to an electrically charged
media or plate. ✔Correct Answer-Electronic air cleaners
Utilizing a filter at decreased airflow levels will ______________the efficiency and ______________
the pressure drop in the duct ✔Correct Answer-Increase, decrease
_________________light can be used inside a duct system to kill mold, fungus, bacteria, and other
living contaminants. ✔Correct Answer-Ultraviolet
When homeowners neglect to change filters, airflow is reduced to the point where the cooling coil
can freeze.This can cause what critical component to fail prematurely ✔Correct Answer-
Compressor
A one inch thick fiberglass air filter is considered: ✔Correct Answer-Low efficiency
HEPA filters capture extremely small particles and are often used in hospitals. HEPA stands for:
✔Correct Answer-High-Efficiency Particulate Air filter
When choosing air filters, particulate filtration efficiency has to be balanced with pressure drop. High
pressure drop across a filter can cause: ✔Correct Answer-A) Reduced equipment efficiency.
Answers| Actual Complete Exam| Already Graded A+
What do technicians call the temperature at which water vapor begins to condense out of the air?
✔Correct Answer-B.ew point
What is the industry standard rate of through-the-evaporator airflow in CFM per ton for most air-
conditioning equipment ✔Correct Answer-B) 400 CFM per ton
______________is the measurement of the total heat content of the air expressed in BTU's per
pound of air. ✔Correct Answer-B) Enthalpy
If a technician wanted to accurately measure static pressure in a duct system, how would she place
the sensing probe of the magnehelic gauge? ✔Correct Answer-A) Place it perpendicular to airflow
___________________represents the amount of water vapor in the air compared to the amount of
water vapor the air can hold ✔Correct Answer-B) Relative humidity
What three environmental conditions have the most effect on comfort? ✔Correct Answer-B)
Temperature, humidity, and air movement
How does the human body expel heat if all the surrounding environment is above the body
temperature? ✔Correct Answer-A) Evaporation
Why does the air's relative humidity affect comfort? SKIP ✔Correct Answer-A) The relative
humidity affects how rapidly perspiration can evaporate
B) Human comfort is not affected by the relative humidity
C) Water molecules in the air act as thermal insulators
D) Water molecules in the air act as thermal conductors
How is the air volume affected by temperature? ✔Correct Answer-D) Air volume increases as the
air temperature increases
What type of measurement is a grain? ✔Correct Answer-A) A grain is a small measurement of
weight
What air property is measured in grains? ✔Correct Answer-C) Specific humidity
In general, which is denser humid air or dry air? ✔Correct Answer-C) Dry air
What is a wet bulb temperature reading? ✔Correct Answer-B) A temperature measured with a
water soaked wick around the thermometer bulb
Relative humidity is measured using ✔Correct Answer-A) Wet bulb and dry bulb temperature
readings
The temperature where water vapor can begin condensing out of the air is the ✔Correct Answer-
D) dew point
, What is specific humidity ✔Correct Answer-C) the weight of water in each pound of dry air,
measured in grains
A graphical representation of air properties is ✔Correct Answer-D) a psychrometric chart
SKIP What would the mixed air temperature be for a system with 30% outdoor air if the outdoor
temperature is 20°F and the return air temperature is 70°F? SKIP THIS ONE ✔Correct Answer-A) 0 3
x 20°F =6°F 0 7 x 70°F = 49°F 6°F + 49°F = 55°F mixed air
A Process that moves horizontally from left to right across a psychometric chart is ✔Correct
Answer-D) a sensible process
A Process that moves vertically up a psychometric chart is ✔Correct Answer-A) a latent process
The enthalpy lines are nearly parallel to the lines for ✔Correct Answer-A) wet bulb temperature
In the heating season, the comfort level can be improved at lower temperatures ✔Correct Answer-
B) By adding humidity to the air
In the cooling season, the comfort level can be improved at higher temperatures ✔Correct
Answer-D) By removing humidity and increasing air velocity
Physically active people feel more comfortable at ✔Correct Answer-A) Lower temperatures
The performance of an air conditioning system can be determined by measuring the airflow and
✔Correct Answer-C) The wet bulb temperature difference across the evaporator coil
While very effective at removing small contaminants, HEPA filters are not used in residential
applications because of what reason? ✔Correct Answer-They cause a high pressure drop in the
duct
_____________________use DC voltage to attract dust and contaminants to an electrically charged
media or plate. ✔Correct Answer-Electronic air cleaners
Utilizing a filter at decreased airflow levels will ______________the efficiency and ______________
the pressure drop in the duct ✔Correct Answer-Increase, decrease
_________________light can be used inside a duct system to kill mold, fungus, bacteria, and other
living contaminants. ✔Correct Answer-Ultraviolet
When homeowners neglect to change filters, airflow is reduced to the point where the cooling coil
can freeze.This can cause what critical component to fail prematurely ✔Correct Answer-
Compressor
A one inch thick fiberglass air filter is considered: ✔Correct Answer-Low efficiency
HEPA filters capture extremely small particles and are often used in hospitals. HEPA stands for:
✔Correct Answer-High-Efficiency Particulate Air filter
When choosing air filters, particulate filtration efficiency has to be balanced with pressure drop. High
pressure drop across a filter can cause: ✔Correct Answer-A) Reduced equipment efficiency.
