B1-9 Air Conditioning; Air Conditioning Systems Flashcards
0
Q
Enthalpy of an air mixture measures the: A) moisture content of the air mixture B) latent heat content of the moist air C) sensible heat content of the dry air D) sensible heat content of the air mixture E) total heat content of the air mixture
A
E) total heat content of the air mixture
1
Q
On the psychrometric chart, lines that originate on the left side, along the saturation line, and slope downward to the right are used to indicate:
A) wet bulb temperature and specific volume
B) Enthalpy and specific volume
C) Enthalpy and wet bulb temperature
D) wet bulb temperature and specific humidity
E) Enthalpy and specific humidity
A
A) wet bulb temperature and specific volume
2
Q
The volume of standard air is: A) 0.633 cu m/kg of dry air B) 0.833 cu m/kg of dry air C) 0.733 cu m/kg of dry air D) 0.933 cu m/kg of dry air E) 0.533 cu m/kg of dry air
A
B) 0.833 cu m/kg of dry air
3
Q
Given a dry bulb temperature reading 28*C and a wet bulb temperature reading of 22*C, the relative humidity is: A) 54% B) 56% C) 62% D) 58% E) 60%
A
E) 60%
4
Q
Sensible heating or cooling, if plotted on the psychrometric chart, is a:
A) curved line sloping up from the left to right
B) straight line sloped up from left to right
C) straight horizontal line
D) straight vertical line
E) straight line sloped up from the right to the left
A
C) straight horizontal line
5
Q
When air is cooled without changing the moisture content, heat added or removed is called: A) evaporation heat B) fusion heat C) latent heat D) sensible heat E) condensation heat
A
D) sensible heat
6
Q
From the group of people listed, the highest effective temperature would be required for a: A) woman over 40 years old B) woman under 40 years old C) man under 40 years old D) woman or man over 40 years old E) man over 49 years old
A
A) woman over 40 years old
7
Q
The single piece of equipment that can be used to cool and humidify the air: A) an evaporator B) an air washer C) a cooling coil D) a DX coil E) a dehumidifier
A
B) an air washer
8
Q
Which of the following is not a centrifugal fan? A) forward curved fan B) backward inclined fan C) radial blade fan D) propeller fan
A
D) propeller fan
9
Q
A fan that is not used for HVAC applications is the: A) backward inclined blade with air foil B) forward curved blade fan C) backward inclined blade fan D) radial blade (straight blade) fan
A
D) radial blade (straight blade) fan
10
Q
A nonoverloading fan (backward inclined fan) characteristic means that the power curve on the performance design:
A) rises from shut off to a maximum and then falls off when approaching free delivery
B) is maximum at shut off and then falls off when approaching free delivery
C) maintains almost a horizontal line
D) continuously rises or falls depending on the air temperature
E) continuously rises from shut off to free delivery
A
A) rises from shut off to a maximum and then falls off when approaching free delivery
11
Q
In an air conditioning duct, the velocity pressure is the pressure over and above: A) dynamic pressure B) suction pressure C) atmospheric pressure D) static pressure E) total pressure
A
D) static pressure
12
Q
The “occupied zone” of an air conditioned space is defined as the space which is:
A) within 2m from the floor and 1m from the walls
B) within 2m from the floor and 2m from the walls
C) filled with conditioned air
D) occupied by occupants
E) above 2m from the floor and 1m from the walls
A
A) within 2m from the floor and 1m from the walls
13
Q
A supply air duct has a total length of 100m, with 70m in the conditioned space. What is the percentage of air leakage that must be counted in the calculation of heat loss for this system? A) 7% B) 30% C) 3% D) 2.1% E) 10%
A
C) 3%
14
Q
The factor used to determine the spacing of fasteners and edge treatment of air conditioning duct liners is the: A) velocity classification of the duct B) fire rating of the duct C) type of adhesive to be used D) liner materials to be used E) type of fastener to be used
A
A) velocity classification of the duct
15
Q
Which of the following statements about leakage from air conditioning ducts is true?
A) air leakage varies from 40-45%
B) leakage inspection can only be done after the duct is covered in insulation
C) losses due to air leakage from furred supply air ducts within the conditioned space can only be evaluated on the basis of judgement
D) losses from bare supply air ducts within the conditioned space have a substantial impact on loss calculations
E) the effects of air leakage in supply air ducts are the same as those in return ducts
A
C) losses due to air leakage from furred supply air ducts within the conditioned space can only be evaluated on the basis of judgement
16
Q
The air vent(s) for air conditioning coils must be installed at:
A) all the above locations
B) the highest point of any vertical loop
C) the highest point of the supply line and return line
D) the highest point of the water coils
E) the highest point of the radiators
A
A) all the above locations
17
Q
In air conditioning coils, the extended surfaces provided by fins is called: A) primary surface B) bare surface C) secondary surface D) contact surface E) tertiary surface
A
C) secondary surface
18
Q
Coils with a flat finned surface and inline tubes:
A) have higher heat transfer rates than tubes with more closely spaced fins
B) are normally used for low temperature cold storage rooms
C) are normally used for high temperature (hot deck) applications
D) have a greater pressure drop that other types
E) cause greater air turbulence than other types of coils
A
B) are normally used for low temperature cold storage rooms
19
Q
To prevent carryover of moisture into supply ducts, most cooling applications require the face velocity be kept between: A) 2-3 m/s B) 2-4 m/s C) 3-6 m/s D) 3-4 m/s E) 2-5 m/s
A
A) 2-3 m/s
20
Q
The use of ethylene glycol solution in a heating coil will result in:
A) reduced frictional losses in the coil and piping
B) better rate of heat transfer
C) an overall higher system efficiency
D) better protection against freezing
E) the requirement of a smaller pump with less horsepower
A
D) better protection against freezing
21
Q
When using water coils to heat air at sub freezing temperatures, it is important that:
A) the hot water flow control valve is able to regulate flow rate
B) the hot water flow rate does not exceed 0.9 m/s
C) a constant flow of water is fed to the coil at all times
D) a counter flow air and water arrangement must be maintained
E) the outside air damper is closed at all times
A
C) a constant flow of water is fed to the coil at all times
22
Q
A flow switch installed on the hot water heating coil of an air conditioning system is to:
A) interlock with the pump to prevent air locking
B) indicate the pump’s pumping efficiency
C) regulate the flow rate
D) interlock with the fans and outside air dampers for freeze protection
E) measure the amount of hot water flow
A
D) interlock with the fans and outside air dampers for freeze protection
23
Q
When a preheat coil is employed in an air conditioning system, to prevent overheating the space temperature, the mixing air temperature is limited to: A) 18*C B) 20*C C) 14.5*C D) 12.5*C E) 16*C
A
A) 18*C
24
```
Outside air is -25*C and is saturated (air at -25*C holds a maximum of 0.0005 kg of water vapour / kg of dry air). This air is drawn into a building and is heated to 22*C (air at 22*C holds a maximum of 0.015 kg of water vapour / kg of dry air). What is the relative humidity of the air inside the building?
A) 3.3%
B) 4.5%
C) 10.6%
D) 0.5%
E) 33%
```
A) 3.3%
25
A steam grid humidifier is typically regulated by:
A) a humidistat that controls the supply fan
B) a humidistat that controls an on off solenoid valve on the steam line
C) a humidistat that modulates a steam control valve
D) a timer that opens and closes a steam control valve
E) a timer that controls a solenoid valve on e steam boiler supply water line
C) a humidistat that modulates a steam control valve
26
```
A residential humidifier commonly installed in the supply plenum of smaller warm air furnaces and consisting of a shallow tray partially filled with water is a:
A) pan type of humidifier with plates
B) power type wetted element humidifiers
C) air washer
D) regenerative type of humidifier
E) bypass type of humidifier
```
A) pan type of humidifier with plates
27
```
The unitary air conditioning system installed at the exterior wall of each room of a building with an adjustable duct connection to outdoors for provision of minimum outdoor air intake is called a:
A) fan coil unit
B) heat pump
C) packaged unit
D) full recirculation unit
E) unit ventilator
```
E) unit ventilator
28
```
A high velocity terminal reheat system differs from a low velocity system in the:
1) supply air temperature
2) supply air velocity
3) size of supply air duct
4) lack of a terminal reheat box
5) increased fan size
A) 1,3 and 5 only
B) 2,3 and 5 only
C) 1,2 and 4 only
D) 2,3 and 4 only
E) 1 and 2 only
```
B) 2,3 and 5 only
29
```
In the single zone constant air volume system, space conditions are maintained by adjusting supply air temperature in response to a thermostat located in the:
A) room or return air duct
B) supply air duct
C) fresh air duct
D) outdoor space
E) mixed air duct
```
A) room or return air duct
30
```
The air handling system that has its cooling coils and heating coils arranged in an offset (parallel) pattern is the:
A) single zone system
B) variable air volume system
C) multiple system
D) unit ventilator
E) single zone system with reheat
```
C) multi zone system
31
```
An air handling system located in a single mechanical room that distributes conditioned air throughout the building by means of ducts is the:
A) central system
B) single system
C) unitary system
D) combined system
E) loop system
```
A) central system
32
On an air conditioning system employing variable air volume with perimeter heating, the room thermostat controls the:
A) inlet vanes of the supply fan
B) outdoor, return, and exhaust dampers on the AHU
C) heating coils and cooling coils on the AHU
D) variable air volume boxes and radiators in the room
E) temperature of coolant in the AHU
D) variable air volume boxes and radiators in the room
33
```
In induction air conditioning systems, the "changeover temperature" is determined by the:
A) relative humidity
B) return air temperature
C) mixed air temperature
D) room temperature
E) outdoor temperature
```
E) outdoor temperature
34
In a constant air volume system with perimeter heating, the set supply air temperature may result in over cooling in rooms if:
A) heating loads are less than maximum
B) dehumidification is excessive
C) humidification is excessive
D) exterior zone heating capacity is too high
E) cooling loads are less than maximum
E) cooling loads are less than maximum
35
```
Heat pump components in a hydronic heat pump system include:
1) DX coil
2) fan
3) filter
4) condenser
5) refrigeration unit with reversing coil
A) 1,2 and 3 only
B) 1,2,4 and 5 only
C) 1,3,4, and 5 only
D) 1,4 and 5 only
E) 1,2,3,4 and 5
```
E) 1,2,3,4 and 5
36
An air to air heat pump is generally used for:
A) oversized commercial buildings
B) larger commercial buildings
C) almost any size of building
D) medium sized commercial buildings
E) residences and small commercial buildings
E) residences and small commercial buildings
37
Coefficient of performance is defined by a unit's:
A) heating output divided by energy input
B) energy output divided by energy input
C) heating output divided by energy input
D) energy input divided by energy output
E) energy input multiplied by heating output
C) heating output divided by energy input
38
To prevent frost buildup on the coils of a runaround system:
A) an on off control is installed on the glycol circulation pump
B) the air is dehumidified prior to entering the coils
C) a 3 way mixing valve is installed in the glycol circulation circuit
D) the latent heat content of exhaust air is increased
E) the glycol temperature is maintained below -3*C
C) a 3 wY mixing valve is installed in the glycol circulation line
39
```
When compared to a combined heating and cooling unit, a heat pump suffers a major disadvantage because of:
A) its initial cost
B) high maintenance costs
C) its complexity
D) its serviceable life
E) its reliability
```
A) its initial cost
40
The advantages of a runaround system include:
1) a wide recovery range of 45-55%
2) no cross contamination is likely
3) full recovery rate can be achieved during colder seasons
4) exhaust and ventilation streams can be remote
5) many exhaust ducts can be grouped on the same system
A) 1,2 and 3 only
B) 2 and 5 only
C) 3,4 and 5 only
D) 2,4 and 5 only
E) 1,2 and 5 only
D) 2,4 and 5 only
41
```
Water spray type humidifiers can be used for humidification purposes, but the control valve to the sprayer must be of the:
A) proportional control type
B) alternating type
C) reverse acting type
D) two position type
E) regulation type
```
D) two position type
42
```
Dehumidification of space air can be achieved by allowing the moist air to pass through:
A) an air washer
B) hot water coils
C) reheat coils
D) hot water sprays
E) a low pressure mixing plenum
```
A) an air washer
43
Ventilation system heating coil regulation is achieved by modulating the:
1) boiler firing rate
2) three way mixing valve on the steam coils
3) control valve to the coil and face and bypass dampers
4) actuators on the steam or water supply and the coil bypass damper
5) heating coil face and bypass dampers
A) 1,2 and 3 only
B) 3,4 and 5 only
C) 2,3 and 5 only
D) 2,3 and 4 only
E) 1,3 and 4 only
B) 3,4 and 5 only
44
The sole purpose of a controller in an HVAC system is to:
A) regulate the system feedback
B) regulate the output of the thermostat
C) bring the controlled variable to its set point
D) vary the opening of a valve
E) regulate the transmission of the feedback signal
C) bring the controlled variable to its set point
45
```
To prevent coils from freezing, the outdoor thermostat starts to open the control valve on the preheat coils when the outdoor temperature drops to:
A) 3.5*C
B) -2*C
C) 0.5*C
D) 5*C
E) 0*C
```
C) 0.5*C
46
When estimating the internal heat gains due to the presence of people, an important factor to consider is:
A) the average age of the people in the building
B) the average weight of the people in the building
C) the ethnic background of the people in the building
D) the activities of the people in the building
E) the gender of the people in the building
D) the activities of the people in the building
47
```
The forcing of air into a building by means of a fan is called:
A) purging
B) exhaustion
C) ventilation load
D) ventilation
E) infiltration
```
D) ventilation
48
The radiation heat gain of a particular building is largely dependent upon:
A) the type of HVAC equipment in the building
B) the number of people occupying the building
C) the usage of the building
D) the orientation and shading of the building
E) the outdoor humidity
D) the orientation and shading of the building
49
```
The reciprocal of thermal conductance is called:
A) factor of thermal transmission
B) thermal transmittance
C) inverse heat exchange factor
D) inverse thermal coefficient
E) thermal resistance
```
E) thermal resistance
50
Relative humidity is defined as:
A) the mass of water vapour in the air at a specific dry bulb temperature
B) the mass of water vapour in the air at a specific wet bulb temperature
C) the ratio of the mass of liquid water in the air to the mass of air
D) the ratio of the mass of dry air to the mass of wet air
E) the ratio of the actual mass of water vapour in a given amount of air compared to the maximum mass the air can hold at that temperature
E) the ratio of the actual mass of water vapour in a given amount of air compared to the maximum mass the air can hold at that temperature
51
```
The difference between the dry bulb temperature and the we bulb temperature is termed:
A) the wet bulb depression
B) the humidity depression
C) the correction factor
D) the dry bulb depression
E) the wet/dry factor
```
A) the wet bulb depression
52
```
Relative humidity is determined using a:
A) dry bulb hydrometer
B) manometer
C) hydrometer
D) physiometer
E) psychrometer
```
E) psychrometer
53
The psychrometric chart:
1) graphically illustrates various properties of air vapour mixtures
2) can be used to check the performance of an air conditioning system
3) is available for different fluids and refrigerants
4) simplifies calculations involving air
A) 1,2,3 and 4
B) 1,2 and 3 only
C) 2,3 and 4 only
D) 1,2 and 4 only
D) 1,2 and 4 only
54
In an air conditioning system, ventilation:
1) provides fresh air to flush out some of the stale air
2) reduces the load on the air conditioning system
3) minimizes air infiltration into the building
4) maintains the building at a positive pressure
A) 1,2 and 3 only
B) 1,3 and 4 only
C) 1,2,3 and 4
D) 2,3 and 4 only
B) 1,3 and 4 only
55
```
When air is cooled without changing the moisture content, the heat added or removed is called:
A) evaporation heat
B) condensation heat
C) sensible heat
D) latent heat
E) fusion heat
```
C) sensible heat
56
```
The comfort of human beings is affected by the atmospheric conditions surrounding them. Which of the following is not an atmospheric condition?
A) temperature
B) air movement
C) air cleanliness
D) saturation temperature
E) elation humidity
```
D) saturation temperature
57
In psychrometry, addition of latent heat only to air will cause:
A) an increase in the dry bulb temperature
B) an increase in the specific humidity
C) a decrease in the specific volume
D) a decrease in the dew point temperature
E) a decrease in the dry bulb temperature
B) an increase in the specific humidity
58
```
When the air distribution system resistance can be determined accurately, a small fan with:
A) gear drive is often selected
B) V-belt drive is often selected
C) direct drive is often selected
D) hydraulic drive is often selected
E) chain drive is often selected
```
C) direct drive is often selected
59
```
Among the types of centrifugal fans, the most energy efficient one is the:
A) propeller fan
B) backward inclined fan with air foil
C) radial blade fan
D) forward curved blade fan
E) backward inclined blade fan
```
B) backward inclined fan with air foil
60
Select the statement about a propeller fan that is false.
A) it is economical for producing large air movements at low pressures
B) it has the ability to move large volumes of air
C) it is widely used in air cooled condensers
D) power requirement is lowest at maximum air delivery
E) it can produce high static pressure
E) it can produce high static pressure
61
```
When a fan outlet is fully open:
A) free air volume delivery exists
B) power requirements are at a minimum
C) fan static efficiency is at a maximum
D) fan static pressure is at a maximum
E) air volume delivery is at a minimum
```
A) free air volume delivery exists
62
```
In air conditioning duct systems, opposed blade dampers are used when:
A) air mixing is required
B) air exhausting is required
C) air diverting is required
D) air volume regulating is required
E) air pressure in the duct is too high
```
D) air volume regulating is required
63
```
The factor used to determine the spacing of fasteners and edge treatment of air conditioning duct liners is the:
A) fire rating of the duct
B) liner materials to be used
C) type of fastener to be used
D) velocity classification of the duct
E) type of adhesive to be used
```
D) velocity classification of the duct
64
```
Manual air conditioning duct dampers are used primarily for:
A) starting and stopping the flow of air
B) balancing the air flow
C) diverting the air flow
D) bypassing the air flow
E) modulating the air flow
```
B) balancing the air flow
65
Semi-rigid fibrous glass blankets are attached to the inside of air conditioning distribution ducts primarily to:
A) stop air leakage in the seams of the duct work
B) act as a fire retardant
C) restrict the spread of smoke in the event of a fire
D) provide thermal insulation
E) attenuate airborne noises
E) attenuate airborne noises
66
Coils with a flat finned surface and inline tubes:
A) have a greater pressure drop than other types
B) have higher heat transfer rates than tubes with more closely spaced fins
C) cause greater air turbulence than other types of coils
D) are normally used for high temperature (hot deck) applications
E) are normally used for low temperature cold storage rooms
E) are normally used for low temperature cold storage rooms
67
The air vent(s) for air conditioning coils must be installed at:
A) the highest point of the supply line and return line
B) the highest point of the water coils
C) the highest point of the radiators
D) the highest point of any vertical loop
E) all of the above locations
E) all of the above locations
68
One of the methods used to provide uniform steam distribution to the individual tubes of a steam coil is:
A) use a steam distributing inner tube
B) employ an orifice at the outlet of each tube
C) use perforated tubes
D) use educator nozzles
E) use larger diameter tubes
A) use a steam distributing inner tube
69
In air conditioning systems, coils with rippled fins and a staggered tube pattern:
A) have a lower pressure drop than other types
B) have a much lower first cost compared to other types
C) usually have the fins bonded to the tubes using glue
D) create more turbulence and improve heat transfer efficiency
E) are normally used for low temperature cold storage rooms
D) create more turbulence and improve heat transfer efficiency
70
```
When a preheat coil is employed in an air conditioning system, to prevent overheating the space temperature, the mixing air temperature is limited to:
A) 12.5*C
B) 14.5*C
C) 16*C
D) 18*C
E) 20*C
```
D) 18*C
71
A flow switch installed on the hot water heating coil of an air conditioning system is to:
A) regulate the flow rate
B) interlock with the fans and outside air dampers for freeze protection
C) indicate the pump's pumping efficiency
D) measure the amount of hot water flow
E) interlock with the pump to prevent air locking
B) interlock with the fans and outside air dampers for freeze protection
72
```
The greatest fears in hot water coil installations handling sub freezing air are:
1) excessive pipe expansion and contraction
2) outside air temperature too low
3) failure of the circulating pump
4) water viscosity too high
5) failure of the heat source
A) 1,2 and 3 only
B) 1,2 and 4 only
C) 1,3 and 5 only
D) 3 and 5 only
E) 2 and 3 only
```
D) 3 and 5 only
73
The steam coils are not likely to freeze, providing:
A) the coils are always under vacuum
B) the tube length is 2.1 m or less
C) there is a steam trap installed
D) the is 100% outside makeup air
E) positive drainage of condensate is ensured
E) positive drainage of condensate is ensured
74
```
Outside air is -25*C and is saturated (air at -25*C holds a maximum of 0.0005 kg of water vapour/kg of dry air). This air is drawn into a building and is heated to 22*C ( air at 22*C holds a maximum of 0.015 kg of water vapour/kg of dry air). What is the relative humidity of the air inside the building?
A) 0.5%
B) 3.3%
C) 4.5%
D) 10.6%
E) 33%
```
B) 3.3%
75
```
Humidify in units that draw warmer air from the furnace return air plenum, pass it through a wetted pad and return it to the supply air plenum are called:
A) pan type humidifiers with plates
B) bypass type humidifiers
C) regenerative type humidifiers
D) atomizing type humidifiers
E) power type wetted element humidifiers
```
B) bypass type humidifiers
76
To protect the electric element in a pan type of humidifier, the system should be equipped with:
A) a ground fault interrupter
B) a high water temperature electric power cutoff
C) a high water level electric power cutoff
D) a circuit breaker
E) a low water level electric power cutoff
E) a low water level electric power cutoff
77
```
The application of an air conditioning system depends on:
1) the geographical location
2) the type of occupancy
3) the local building code
4) the building layout
5) the national building code
A) 2,3 and 4 only
B) 1,2 and 5 only
C) 1,3 and 5 only
D) 1,2 and 4 only
E) 1,2 and 3 only
```
D) 1,2 and 4 only
78
Advantages to using a central air conditioning system in a larger building include:
1) ease of installation
2) effective control of noise and vibration
3) lower space requirements for equipment
4) minimal cost for ductwork
5) lower equipment initial capital cost per unit output
A) 3 and 5 only
B) 1,2 and 5 only
C) 1,2 and 4 only
D) 2 and 5 only
E) 1,3 and 4 only
D) 2 and 5 only
79
```
An air handling system located in a single mechanical room that distributes conditioned air throughout the building by means of ducts is the:
A) unitary system
B) combined system
C) single system
D) central system
E) loop system
```
D) central system
80
```
To offset the heat gains through a building's exterior shell and from internal heat sources, an air conditioning system must employ:
A) air recirculation
B) a humidifier
C) air filtration
D) a dehumidifier
E) a cooling source
```
E) a cooling source
81
```
The unitary air conditioning system installed at the exterior wall of each room of a building with an adjustable duct connection to outdoors for provision of minimum outdoor air intake is called a:
A) full recirculation unit
B) heat pump
C) unit ventilator
D) fan coil unit
E) packaged unit
```
C) unit ventilator
82
```
In the hydronic heat pump system, water temperature in the hydronic circuit is maintained within the range of:
A) 9-12.5*C
B) 9-20*C
C) 15-20*C
D) 15-32*C
E) 20-42*C
```
D) 15-32*C
83
On an air conditioning system employing variable air volume with perimeter heating, the room thermostat controls the:
A) variable air volume boxes and radiators in the room
B) inlet vanes of the supply fan
C) outdoor, return, and exhaust dampers on the AHU
D) temperature of coolant in the AHU
E) heating coils and cooling coils on the AHU
A) variable air volume boxes and radiators in the room
84
In a constant air volume system with perimeter heating, the set supply air temperature may result in over cooling in rooms if:
A) heating loads are less than maximum
B) exterior zone heating capacity is too high
C) humidification is excessive
D) dehumidification is excessive
E) cooling loads are less than maximum
E) cooling loads are less than maximum
85
```
The fan coil unit that achieves best control of room temperature on a year round basis utilizes a:
A) single pipe connection
B) two pipe connection
C) three pipe connection
D) four pipe connection
E) none of the above
```
D) four pipe connection
86
```
A heat pump is basically a modified:
A) water pump used to pump hot water from a stored heat sink
B) absorption refrigeration system
C) compression refrigeration system
D) hot water pumping system
E) heat pipe
```
C) compression refrigeration system
87
To convert a refrigeration system into a heat pump:
1) a larger condenser cooling fan must be added
2) a reversing valve must be added
3) a second expansion valve must be added
4) two check valves must be mounted in parallel to the expansion valve
5) the refrigerant must be changed to a different type
A) 2,3 and 5 only
B) 1,2,3 and 5 only
C) 1,2 and 4 only
D) 2,3 and 4 only
D) 2,3 and 4 only
88
```
The term "coefficient of performance" (C.O.P.) is used for rating:
A) heat pipes
B) heat pumps
C) induction units
D) heating coil capacity
E) refrigeration compressors
```
B) heat pumps
89
Advantages of the thermal wheel recovery system include:
1) both sensible heat and latent heat recovery are possible
2) no possibility of cross contamination
3) recovery over a wide range of temperature
4) no additional ducting is required
5) no piping pump, or circulating fluid is required
A) 2,3 and 4 only
B) 1,2 and 3 only
C) 1,4 and 5 only
D) 2,3 and 5 only
E) 1,3 and 5 only
E) 1,3 and 5 only
90
```
The heat recovery system that has the advantage of being treated to resist corrosion is the:
A) heat pipe
B) heat pump
C) induction system
D) thermal wheel
E) runaround system
```
A) heat pipe
91
The system that has little threat of preheat coil freeze up is the:
A) preheat system with face and bypass dampers
B) induction preheat system
C) steam heating system
D) multiple preheat coil system
E) minimum outdoor air system
A) preheat system with face and bypass dampers
92
```
When an air conditioning control system becomes complex, the preferred control signal transmission medium is:
A) electric
B) electronic
C) mechanic
D) pneumatic
E) it makes no difference
```
D) pneumatic
93
```
To manually reposition an air conditioning system's outside air damper, the device that must be installed is:
A) a feedback relay
B) an air mixer
C) a three phase damper interchange
D) an offset return air duct
E) a gradual switch
```
E) a gradual switch
94
```
Outside air control determines the:
A) air circulation velocity
B) zone flow rate
C) proportion of outside air to returned air
D) air humidity
E) air temperature
```
C) proportion of outside air to returned air
95
```
Ventilation is the continuous adjustment of the quantity of outdoor air brought into an air circulation system and is referred to as:
A) make up air control
B) outside air control
C) independent air control
D) minimum air control
E) mix air control
```
B) outside air control
96
```
In calculating air filtration, the more accurate method is:
A) the air change method
B) the conduction method
C) the recirculation air method
D) the crack method
E) the minimum air method
```
D) the crack method
97
```
The thermal transmission, by conduction only, through a unit area of homogeneous material is defined as:
A) factor of thermal transmission
B) thermal coefficient
C) thermal transmittance
D) thermal conductivity
E) heat exchange factor
```
D) thermal conductivity
98
In determining the heat conducted through a surface, the U-factor is the:
A) overall coefficient of heat transmission
B) inverse heat exchange factor
C) thermal conductivity
D) overall coefficient of thermal resistance
E) thermal conductance
A) overall coefficient of heat transmission
99
The radiation heat gain of a particular building is largely dependant upon:
A) the type of HVAC equipment in the building
B) the usage of the building
C) the number of people occupying the building
D) the outdoor humidity
E) the orientation and shading of the building
E) the orientation and shading of the building
