Unit10 HVAC Fundamentals for Facility Operators

Question 1

Very low humidity causes
Select one:
a. increased perspiration
b. static electricity build-up 
c. headaches
d. wooden furniture and hardwood floors to swell

Answer 1

b. static electricity build-up

Question 2

Activated carbon will absorb odours and objectionable gases by up to \_\_\_\_\_ of its own weight before requiring replacement.  
Select one:
a. 10% 
b. 20%  
c. 30% 
d. 50%

Answer 2

b. 20%

Question 3

The aspect of air conditioning that is responsible for replenishing stale indoor air with outside air is
Select one:
a. Heating
b. Cooling
c. Ventilation 
d. Humidification

Answer 3

c. Ventilation

Question 4

The key criterion when designing an HVAC system is:

Select one:

a. temperature control
b. humidity control
c. human health
d. air velocity

Answer 4

c. human health

Question 5

The propeller axial flow fan:
Select one:
a. Produces low capacity, low pressure air movement
b. Finds application in unit heaters, air-cooled condensers, and as an exhaust fan for ventilation purposes
c. Is widely used in commercial air conditioning ducting
d. Requires the least power at minimum air delivery

Answer 5

b. Finds application in unit heaters, air-cooled condensers, and as an exhaust fan for ventilation purposes

Question 6

Steam grid humidifiers used in HVAC systems work by injecting steam into
Select one:
a. the make-up air stream
b. the rooms to be humidified
c. the spray water of an air washer
d. the supply air stream

Answer 6

d. the supply air stream

Question 7

With regard to vacuum breakers, which of the following statements is FALSE?
Select one:
a. Vacuum breakers prevent freeze-ups caused by negative pressure in steam heating coils.
b. Vacuum breakers must be situated before the control valve, and as near as possible to the inlet connection of the coil.
c. Check valves used as vacuum breakers may be connected to the condensate return header.
d. Vacuum breakers are essential for satisfactory functioning of steam traps

Answer 7

b. Vacuum breakers must be situated before the control valve, and as near as possible to the inlet connection of the coil.

Question 8

With respect to steam trap installations, which of the following statements is FALSE?
Select one:
a. Choose a steam trap based on the pressure difference across the trap, and a minimum capacity corresponding to three times the coil condensate rate.
b. Locate the steam trap so that its outlet is at least 30 cm above the coil condensate outlet.
c. Trap each steam coil separately.
d. Drip the steam supply main through a steam trap into the return condensate main, and not through the steam coil.

Answer 8

b. Locate the steam trap so that its outlet is at least 30 cm above the coil condensate outlet.

Question 9

One of the advantages of a common exhaust duct system used for ventilation in a large building is:
Select one:
a. There is no fan to maintain
b. The building can be maintained at a slight negative pressure at all times.
c. There is only one fan to maintain
d. The building can be kept odour-free

Answer 9

c. There is only one fan to maintain

Question 10

The residential humidifier which is commonly used in the supply plenum of smaller warm air furnaces and consists of a shallow tray partially filled with water is called a: 
Select one:
a. Bypass humidifier
b. Wetted element humidifier
c. Pan type humidifier 
d. Power type humidifier

Answer 10

c. Pan type humidifier

Question 11

Which of the following is NOT a common complaint related to HVAC system operation?

Select one:

a. too much or too little air movement
b. the air is too humid or too dry
c. rooms are too hot or too cold
d. the smell of too much perfume or cologne

Answer 11

d. the smell of too much perfume or cologne

Question 12

The purpose of a vacuum breaker used with steam heating coils is to:
Select one:
a. Prevent freezing caused by a vacuum or negative pressure in the steam coil.
b. Prevent negative air pressure in the conditioned space.
c. Ensure proper operation of the steam control valve.
d. Prevent flashing of the condensate within the steam coil.

Answer 12

a. Prevent freezing caused by a vacuum or negative pressure in the steam coil.

Question 13

__________ dampers have the blades linked so the adjacent blades rotate in opposite directions.

Select one:

a. Parallel blade
b. Opposed blade
c. Bypass
d. Fire

Answer 13

b. Opposed blade

Question 14

Which of the following units is LEAST likely to be used when measuring HVAC duct static pressure?

Select one:

a. inches of water
b. kPa
c. cm of water
d. inches of mercury

Answer 14

d. inches of mercury

Question 15

If air at 13°C can hold a maximum of 0.0032 kg of moisture per kilogram of air, what is the relative humidity if the air contains 0.0015 kg of moisture per 1 kg of air? 
Select one:
a. 2.13% 
b. 0.4% 
c. 47%  
d. 32%

Answer 15

c. 47%

Question 16

To prevent freezing of a steam coil, when steam pressure at the coil inlet is too low:
Select one:
a. A second preheat coil must be installed at the outside air inlet.
b. A two-position steam control valve must be installed at the coil inlet.
c. The supply air fan is stopped and the outside air dampers are shut.
d. Inverted bucket steam traps must be used.

Answer 16

c. The supply air fan is stopped and the outside air dampers are shut.

Question 17

Calculations of return air duct leakage include:
Select one:
a. 3% seepage if the return air duct is located outside the conditioned space.
b. 3% seepage if the return air duct is located both inside and outside the conditioned space.
c. 10% leakage if the return air duct is located inside the conditioned space.
d. 3% leakage if the return air duct is located inside or outside the conditioned space.

Answer 17

a. 3% seepage if the return air duct is located outside the conditioned space.

Question 18

Air conditioning ducts are classified as:
Select one:
a. Low pressure, medium pressure, and high pressure
b. Fire resistant and flame-suppressing
c. Light, medium, and heavy gauge
d. Heating and cooling

Answer 18

a. Low pressure, medium pressure, and high pressure

Question 19

Air ducts of large dimensions must be diagonally creased
Select one:
a. To provide stiffness
b. To allow expansion and contraction
c. To increase air velocity
d. To decrease air friction in the duct work

Answer 19

a. To provide stiffness

Question 20

Viscous impingement filters are highly efficient in the removal of:
Select one:
a. Fine dust, fumes, and smoke 
b. Bacteria and spores 
c. Cooking odours 
d. Dust and pollen

Answer 20

d. Dust and pollen

Question 21

Which of the following is an advantage of medium and high pressure HVAC duct systems?
Select one:
a. Lower operating cost
b. No need for costly noise suppression devices
c. Less costly fabrication and installation
d. Less physical space requirements

Answer 21

d. Less physical space requirements

Question 22

Air duct velocity pressure is measured by connecting a:
Select one:
a. Manometer to the side of an air duct
b. Bourdon tube to the air duct
c. Pressure gauge to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow
d. Manometer to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow

Answer 22

c. Pressure gauge to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow

Question 23

The difference between the wet- and dry-bulb readings is called the:
Select one:
a. Wet-bulb depression 
b. Relative humidity
c. Dew point
d. Dry bulb depression

Answer 23

a. Wet-bulb depression

Question 24

Wet-bulb temperature is:
Select one:
a. The temperature indicated by a thermometer whose bulb covered by a water-wetted wick, and exposed to a rapidly moving stream of air
b. The dew point temperature
c. Always less than the dry-bulb temperature
d. The product of the dry-bulb temperature times the relative humidity.

Answer 24

a. The temperature indicated by a thermometer whose bulb covered by a water-wetted wick, and exposed to a rapidly moving stream of air

Question 25

Air washers, used in HVAC systems, cannot: 
Select one:
a. Cool the air 
b. Remove tobacco smoke  
c. Dehumidify the air 
d. Heat the air

Answer 25

b. Remove tobacco smoke

Question 26

Backward inclined centrifugal fans:
Select one:
a. Require more horsepower than the forward curved fans to deliver a specified volume of air
b. Are quieter than forward curved fans
c. Are less efficient than forward curved fans
d. Are noisier than forward curved fans

Answer 26

b. Are quieter than forward curved fans

Question 27

Humidifying units that force warm air through a wet pad, and return the air to the room, are called: 
Select one:
a. Pan type humidifiers with plates 
b. Atomizing humidifiers 
c. Bypass type humidifiers 
d. Wetted element humidifiers

Answer 27

d. Wetted element humidifiers

Question 28

Bacteria can range from_____________ in size.

Select one:

a. 0.2 to 5 microns
b. 5 to 150 microns
c. 0.2 to 0.3 microns
d. 150 to 1000 microns

Answer 28

a. 0.2 to 5 microns

Question 29

Ultraviolet light is used to remove \_\_\_\_\_ from the air. 
Select one:
a. Dust and pollen 
b. Fine dust and smoke 
c. Bacteria  
d. Mists and fogs 
Feedback
The correct answer is: Bacteria

Answer 29

c. Bacteria

Question 30

The inverted bucket steam trap, as applied to steam heating coils,
Select one:
a. Is used when the coil steam pressure is higher than 172 kPa or 25 psig
b. Is used when considerable air venting is required.
c. Does not require a strainer.
d. Is recommended when condensate flows by gravity into a return main at atmospheric pressure.

Answer 30

a. Is used when the coil steam pressure is higher than 172 kPa or 25 psig

Question 31

An air filter capable of removing particles as small as 0.3 micron in diameter with 99% efficiency is a

Select one:

a. a viscous impingement filter.
b. an odour absorber.
c. a HEPA filter.
d. a charged-media air cleaner.

Answer 31

c. a HEPA(High-Efficiency Particulate Air) filter.

Question 32

An HVAC system is a ___________ system.

Select one:

a. Heating, Ventilating, Air movement, and Cooling system
b. Humidification, Ventilation, Air filtration, and Conveying system
c. Heating, Ventilation, and Air Conditioning system
d. Humidifying, Ventilating, Air Conditioning and Cooling system

Answer 32

c. Heating, Ventilation, and Air Conditioning system

Question 33

Buildings require heat sources to:
Select one:
a. Offset the heat gain from the atmosphere
b. Replace the ventilation air
c. Replace the exhaust air
d. Offset the building's heat losses

Answer 33

d. Offset the building’s heat losses

Question 34

Short radius elbows should be provided with 
Select one:
a. Stiffeners 
b. Turning vanes  
c. Mitre elbows
d. Noise attenuators

Answer 34

b. Turning vanes

Question 35

Which of the following statements about duct leakage losses is true?
Select one:
a. The effects of air leakage in supply air ducts are the same as those in return ducts.
b. For insulated supply air ducts located within the conditioned spaces, determination of air leakage is evaluated based on judgment, depending on whether leaked air enters the conditioned space, or is lost.
c. Losses from bare supply air ducts within the conditioned space have a substantial impact on loss calculations.
d. Air leakage varies from 40% to 45%.

Answer 35

b. For insulated supply air ducts located within the conditioned spaces, determination of air leakage is evaluated based on judgment, depending on whether leaked air enters the conditioned space, or is lost.

Question 36

Steam coils with a short tube length of 1.1 m or less, in comparison to steam coils with long tube lengths,
Select one:
a. are more likely to freeze, even if the steam trap is properly chosen
b. require two preheat coils to prevent freeze-up.
c. must use two-position steam valves to prevent freeze-up.
d. are less likely to freeze if the steam trap is properly chosen and the coil is properly piped.

Answer 36

d. are less likely to freeze if the steam trap is properly chosen and the coil is properly piped.

Question 37

Electronic air cleaners are divided into ____________ classes.
Select one:
a. Commercial and residential
b. High voltage and low voltage
c. Electrostatic precipitators and charged media electronic
d. AC and DC

Answer 37

c. Electrostatic precipitators and charged media

Question 38

Which of the following statements describes Total Pressure?

Select one:

a. Static Pressure - Velocity Pressure
b. Velocity Pressure + Static Pressure
c. Velocity Pressure - Static Pressure
d. Atmospheric Pressure + Static Pressure

Answer 38

b. Velocity Pressure + Static Pressure

Question 39

Leakage from supply air ducts, when the ductwork is installed completely outside the conditioned space,
Select one:
a. Adds load to the calculated sensible heat requirements of the conditioned space
b. Adds load to the calculated latent heat load
c. Must be subtracted from the return air duct leakage
d. Must be added to the return air duct leakage

Answer 39

a. Adds load to the calculated sensible heat requirements of the conditioned space

Question 40

Steam coils with long tube lengths:
Select one:
a. Are likely to freeze when the incoming air is extremely cold (say -35°C)
b. Have the greatest freezing problems at temperatures approaching –2°C.
c. Cause overheating and poor set point tracking during cold weather
d. Are unlikely to freeze at any temperature.

Answer 40

b. Have the greatest freezing problems at temperatures approaching –2°C.

Question 41

The dew point is the:
Select one:
a. Temperature at which water vapour will start to be absorbed into the air
b. Temperature below which water vapour will start to condense out of the air
c. Pressure below which water vapour will start to condense out of the air
d. Temperature at which water will start to evaporate

Answer 41

b. Temperature below which water vapour will start to condense out of the air

Question 42

___________ dampers are controlled in such a way that they are either fully open or fully closed.

Select one:

a. Two-position
b. Return air
c. Backdraft
d. Relief

Answer 42

a. Two-position

Question 43

Air washers can achieve dehumidification when
Select one:
a. the water temperature is greater than the dry bulb temperature.
b. the spray water is cooled to below the dew point.
c. the return air is more humid than the outside air.
d. the specific humidity of the air is greater than the relative humidity.

Answer 43

b. the spray water is cooled to below the dew point.

Question 44

It is good design practice to select a steam coil size so that:
Select one:
a. 100% of the coil capacity is needed when the air temperature entering the coil is –1°C
b. At least 40% of the coil capacity is needed when the air temperature entering the coil is –1°C
c. At least 80% of the coil capacity is needed when the air temperature at the coil inlet is –1°C
d. At least 10% of the coil capacity is needed when the air temperature at the coil inlet is –5°C

Answer 44

b. At least 40% of the coil capacity is needed when the air temperature entering the coil is –1°C

Question 45

Which of the following is NOT a type of centrifugal fan?
Select one:
a. Forward curved fan wheel
b. The propeller fan
c. The radial blade fan
d. The backward inclined airfoil blade fan

Answer 45

b. The propeller fan

Question 46

The static pressure measured in an air duct is measured by connecting a:
Select one:
a. Manometer to the side of an air duct
b. Bourdon tube to the air duct
c. Pressure gauge to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow
d. Manometer to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow

Answer 46

a. Manometer to the side of an air duct

Question 47

`Total pressure exerted by the air is the sum of:
Select one:
a. Static suction lift and static discharge head
b. Head pressure and suction pressure
c. Static pressure and velocity pressure
d. Suction pressure and velocity pressure

Answer 47

c. Static pressure and velocity pressure

Question 48

The two general groups of fans are: 
Select one:
a. Positive displacement and dynamic 
b. High volume and low volume 
c. Positive displacement and axial flow 
d. Centrifugal and axial flow

Answer 48

d. Centrifugal and axial flow

Question 49

Freezing problems in steam coils with long tube lengths, when heating large amounts of low temperature outside air, can be minimized using
Select one:
a. Preheat coils controlled by an outdoor temperature controller.
b. Modulating control valves to control the steam heating coil output.
c. A controller that fully closes the outside air dampers when the outside air temperature drops to below freezing.
d. An over-sized steam flow control valve.

Answer 49

a. Preheat coils controlled by an outdoor temperature controller.

Question 50

Fibreglass ducts are used:
Select one:
a. In high pressure systems 
b. To handle air with high moisture levels, oily vapours, and grease 
c. Where high strength is required 
d. In some low pressure systems

Answer 50

d. In some low pressure systems

Question 51

Electrostatic filters are highly efficient in the removal of: 
Select one:
a. Odours 
b. Fine dust, smoke, and fumes  
c. Bacteria and spores
d. Lint

Answer 51

b. Fine dust, smoke, and fumes

Question 52

A buried ventilation duct in an older building draws air from a chemistry lab fume hood. The duct would likely be constructed of
Select one:
a. Galvanized steel sheet metal
b. Aluminum sheet metal
c. Cement asbestos 
d. Fiberglass

Answer 52

c. Cement asbestos

Question 53

Materials used in sheet metal ducts are:
Select one:
a. Galvanized steel and copper
b. Galvanized steel and aluminum
c. Galvanized or black steel, aluminum, copper, and stainless steel
d. Galvanized aluminum

Answer 53

c. Galvanized or black steel, aluminum, copper, and stainless steel

Question 54

Air that is fully saturated has a relative humidity of:
Select one:
a. 90%
b. 96.8%
c. 100%
d. 100 grams of moisture per 100 kg of dry air

Answer 54

c. 100%

Question 55

An advantage of a fully mechanical ventilation system is:
Select one:
a. It is self powered.
b. The system supplies a controlled amount of filtered and heated air.
c. The entire system only requires one fan.
d. The air is stratified, to help with filtration.

Answer 55

b. The system supplies a controlled amount of filtered and heated air.

Question 56

Dry-bulb temperature is:
Select one:
a. The same as the wet-bulb temperature, if the relative humidity is less than 100%
b. Not as important as wet-bulb temperature
c. The temperature of the air measured with an ordinary thermometer
d. The dew point temperature

Answer 56

c. The temperature of the air measured with an ordinary thermometer

Question 57

Which of the following steam traps are recommended for use with steam coils operating at low or medium steam pressure? 
Select one:
a. Inverted bucket trap 
b. Thermostatic trap  
c. Float and thermostatic trap  
d. Impulse trap

Answer 57

c. Float and thermostatic trap

Question 58

Which one of the following air cleaning devices can be used for the removal of gases and vapour? 
Select one:
a. Air washers 
b. Electronic air cleaners 
c. Charcoal absorbers  
d. Air sterilizers

Answer 58

c. Charcoal absorbers

Question 59

Axial flow fans:
Select one:
a. Have maximum horsepower requirements at maximum air delivery
b. Have minimum horsepower requirements at maximum air delivery
c. Are the best choice to move large volumes of air at high static pressures
d. Are the least economical choice when large volumes of air must be moved at low pressures.

Answer 59

b. Have minimum horsepower requirements at maximum air delivery

Question 60

In a a system with mechanical air intake and natural exhaust ventilation, the building static pressure is maintained
Select one:
a. Slightly below atmospheric pressure 
b. At atmospheric pressure 
c. Slightly above atmospheric pressure  
d. Well above atmospheric pressure

Answer 60

c. Slightly above atmospheric pressure

Question 61

The outside air is a a temperature of -25°C, and is saturated. This air is drawn into the building and heated to 21°C. What is the relative humidity of the air after passing through the heating coil? (Air at -25°C holds a maximum of 0.0005 kg of moisture/kg of water, and air at 21°C holds a maximum of 0.015 kg of moisture/kg of water). 
Select one:
a. 3.3%  
b. 0.015% 
c. 30% 
d. 10.6%

Answer 61

a. 3.3%

Question 62

Air duct velocity pressure is measured by connecting a:
Select one:
a. Manometer to the side of an air duct
b. Bourdon tube to the air duct
c. Pressure gauge to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow
d. Manometer to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow

Answer 62

d. Manometer to the side of a duct, with a sensing tube extending inside of the duct directed toward the airflow

Question 63

Modulating control valves:
Select one:
a. Should be over-sized to prevent steam coil freeze-up.
b. Can successfully control steam coils, as long as the air entering the coil is at or above 1.5°C .
c. Are used for steam coils where the condensate must be lifted to an overhead condensate return line.
d. Are mainly used for steam coils when the entering air temperature is below 1.5°C.
e. Are never used to control steam coils, regardless of inlet air temperature.

Answer 63

b. Can successfully control steam coils, as long as the air entering the coil is at or above 1.5°C .

Question 64

Humidification in residences equipped with ducted warm air heating systems:
Select one:
a. Is not necessary because the humidity does not change with heating
b. Is accomplished by placing a single humidifier in the furnace plenum or in the warm air duct
c. Is accomplished by installing a secondary hot water heating system
d. Requires separate humidifiers for each heated area

Answer 64

b. Is accomplished by placing a single humidifier in the furnace plenum or in the warm air duct

Question 65

Specific humidity is the:
Select one:
a. Ratio of the actual amount of water vapour present in the air, to the amount of water vapour the air can contain when it is saturated
b. Percentage of moisture in the air
c. Actual moisture content of air expressed as kg of moisture per kg of dry air
d. Ratio of dry air to moisture

Answer 65

c. Actual moisture content of air expressed as kg of moisture per kg of dry air

Question 66

The purpose of humidification is to:
Select one:
a. Add moisture to the air during the cooling season
b. Add moisture to the air during the heating season
c. Remove moisture from the air during the heating season
d. Remove moisture from the air during the cooling season

Answer 66

b. Add moisture to the air during the heating season

Question 67

An air filter capable of removing particles as small as 0.3 micron in diameter with 99% efficiency is a

Select one:

a. a viscous impingement filter.
b. a charged-media air cleaner.
c. an odour absorber.
d. a HEPA filter.

Answer 67

d. a HEPA filter.

Question 68

__________ dampers have the blades linked so the adjacent blades rotate in opposite directions.

Select one:

a. Opposed blade
b. Fire
c. Parallel blade
d. Bypass

Answer 68

a. Opposed blade

Question 69

A buried ventilation duct in an older building draws air from a chemistry lab fume hood. The duct would likely be constructed of
Select one:
a. Galvanized steel sheet metal
b. Aluminum sheet metal
c. Cement asbestos 
d. Fiberglass

Answer 69

c. Cement asbestos

Question 70

To prevent freezing of a steam coil, when steam pressure at the coil inlet is too low:
Select one:
a. A second preheat coil must be installed at the outside air inlet.
b. A two-position steam control valve must be installed at the coil inlet.
c. The supply air fan is stopped and the outside air dampers are shut.
d. Inverted bucket steam traps must be used.

Answer 70

c. The supply air fan is stopped and the outside air dampers are shut.

Question 71

Modulating control valves:
Select one:
a. Are never used to control steam coils, regardless of inlet air temperature.
b. Are used for steam coils where the condensate must be lifted to an overhead condensate return line.
c. Should be over-sized to prevent steam coil freeze-up.
d. Can successfully control steam coils, as long as the air entering the coil is at or above 1.5°C .
e. Are mainly used for steam coils when the entering air temperature is below 1.5°C.

Answer 71

d. Can successfully control steam coils, as long as the air entering the coil is at or above 1.5°C .

Question 72

Which of the following is an advantage of medium and high pressure HVAC duct systems?
Select one:
a. Lower operating cost
b. No need for costly noise suppression devices
c. Less costly fabrication and installation
d. Less physical space requirements

Answer 72

d. Less physical space requirements