75)
75)
A variable–air–volume zone system can:
A)
Match the airflow and system capacity to the load.
B)
Overblow a zone if only one zone is calling.
C)
Require more bypass air than a traditional zone system.
D)
Allow the homeowner to dial in the desired airflow.
Answer:
A
Explanation:
76)
76)
Barometric dampers are operated by:
A)
A pair of large magnetic solenoids.
B)
A damper motor, pulley, and belt.
C)
A small gear motor.
D)
The air pressure difference across the damper.
Answer:
D
Explanation:
77)
77)
A TAB technician determines that the total airflow entering the return grilles is much lower than
the amount of air the blower is moving. This indicates that:
A)
There are leaks in the supply–side ductwork.
B)
There is too much restriction in the return–side ductwork.
C)
There is too much restriction in the supply–side ductwork.
D)
There are leaks in the return–side ductwork.
Answer:
D
Explanation:
78)
78)
A pitot tube is used to measure:
A)
Barometric pressure in mechanical rooms.
B)
Water pressure in recirculating water systems.
C)
Water velocity in recirculating water systems.
D)
Velocity pressure in ducts.
Answer:
D
Explanation:
21
79)
79)
Organizations that support the TAB industry by developing standards and offering certification
include:
A)
NFPA, NEC, and NEBB.
B)
NEC, UL, and CSA.
C)
ETL, ASME, and NFPA.
D)
AABC, TABB, and NEBB.
Answer:
D
Explanation:
80)
80)
The velocity pressure of air moving through ductwork is measured:
A)
By taking the pressure with the open end of the tube facing the airstream.
B)
By subtracting static pressure from total pressure.
C)
By holding the open end of the tube perpendicular to the air stream.
D)
By subtracting total pressure from static pressure.
Answer:
B
Explanation:
81)
81)
What are TAB contractors commissioned to do on HVACR systems?
A)
Calibrate test instruments.
B)
Complete installation of the entire system.
C)
Perform quality control checks on a system.
D)
Train technicians on how to operate systems.
Answer:
C
Explanation:
82)
82)
The purpose of TAB is to document that:
A)
The system is performing as designed.
B)
The duct system does not leak.
C)
Initial startup adjustments are made.
D)
Each area has the minimum required ventilation.
Answer:
A
Explanation:
22
83)
83)
The formula for measuring airflow using temperature rise is:
A)
CFM = Temperature Rise ÷ (1.08 × Btuh).
B)
CFM = Btuh ÷ (1.08 × Temperature Rise).
C)
CFM = (Btuh × 1.08) ÷ Temperature Rise.
D)
CFM = Btuh × 1.08 × Temperature Rise.
Answer:
B
Explanation:
84)
84)
The amount of moisture in the air can be measured with:
A)
A hot wire anemometer.
B)
An electronic barometer.
C)
A chronometric tachometer.
D)
An electronic hygrometer.
Answer:
D
Explanation:
85)
85)
When performing a test and balance procedure on a zoned system, correct airflow should first be
established:
A)
For the branch with the highest CFM requirement in each zone.
B)
For the branch with the lowest CFM requirement in each zone.
C)
For each branch before balancing the zones.
D)
For each zone before balancing the individual branches.
Answer:
D
Explanation:
86)
86)
The dampers on registers are normally not used for balancing the system airflow because:
A)
Most registers do not have integral dampers.
B)
They will produce excessive noise in the space.
C)
They do not seal off tightly enough to be used for balancing dampers.
D)
They are more difficult to adjust than dampers in the duct system.
Answer:
B
Explanation:
23
87)
87)
A sling psychrometer can be used to determine the relative humidity by comparing:
A)
The still reading and the moving reading.
B)
The psychrometer reading to a barometer reading.
C)
The psychrometer reading to the manufacturer’s charging chart.
D)
The dry–bulb and wet–bulb readings.
Answer:
D
Explanation:
88)
88)
What is the free area of a register or grille?
A)
The portion of the register that is not being used.
B)
The area found by multiplying the register height and width.
C)
The area of the register excluding the outside edge.
D)
The amount of the grille face area that is open.
Answer:
D
Explanation:
89)
89)
An anemometer is used to measure:
A)
Feet of air for air velocity calculations.
B)
Feet of water for water flow calculations.
C)
Volume of air for air volume calculations.
D)
Rotational speed.
Answer:
A
Explanation:
90)
90)
In general, when a blower motor moves more air, its amp draw will:
A)
Increase.
B)
Stay the same.
C)
Decrease.
D)
Will not be affected because there is no correlation between airflow and current draw.
Answer:
A
Explanation:
24
91)
91)
A tachometer is used to measure:
A)
Energy use.
B)
Wind speed.
C)
Rotational speed.
D)
Air velocity.
Answer:
C
Explanation:
92)
92)
TAB stands for:
A)
Temperature adjusting and balancing.
B)
Testing and balancing.
C)
Testing adjusting and billing.
D)
Trimming and balancing.
Answer:
B
Explanation:
93)
93)
Which statement most accurately describes TAB?
A)
TAB is a type of test instrument.
B)
TAB is an optional part of the installation process.
C)
TAB is used to conduct measurements and adjustments that are specific to testing and
balancing, which are not normally performed in regular HVACR work.
D)
TAB is a training organization within the HVACR industry.
Answer:
C
Explanation:
94)
94)
Stroboscopes and tachometers are used to measure:
A)
Humidity.
B)
Rotational speed.
C)
Temperature.
D)
Air velocity.
Answer:
B
Explanation:
25
95)
95)
What is galvanic corrosion?
A)
Corrosion due to attack by metal–eating organisms
B)
Corrosion due to chemical incompatibility between the coil and the refrigerant
C)
Corrosion at the contact point of two types of metal in the presence of an electrolyte
D)
Corrosion due to oxidation and chemical attack
Answer:
C
Explanation:
96)
96)
Restaurants, nightclubs, and casino applications all require:
A)
High rates of ventilation to exhaust odors and fumes.
B)
Large quantities of additional humidification due to the high occupancy rates.
C)
Extra heating due to the high occupancy rates.
D)
Quieter systems than other types of commercial structures.
Answer:
A
Explanation:
97)
97)
Chilled water systems use a primary refrigerant to remove heat from a secondary refrigerant in a
chiller unit. What is the secondary refrigerant in such systems?
A)
R–22
B)
Water
C)
R–134A
D)
Ammonia
Answer:
B
Explanation:
98)
98)
One advantage that steam systems have over hot water systems is that steam systems do not
require:
A)
TXV valves.
B)
Bypass valves.
C)
Compressor unloaders.
D)
Circulating pumps.
Answer:
D
Explanation:
26
99)
99)
What is a secondary refrigerant?
A)
A secondary refrigerant is used to replace an older CFC or HCFC.
B)
A secondary refrigerant adds extra cooling capacity to the primary refrigerant.
C)
A secondary refrigerant absorbs heat through temperature change only.
D)
A secondary refrigerant is used in the second stage of a staging system.
Answer:
C
Explanation:
100)
100)
What is the purpose of the low ambient control on a commercial air conditioner?
A)
To prevent the system from operating at low ambient temperatures
B)
To cycle the air conditioning system based on ambient temperature
C)
To energize heat strips to control the ambient temperature
D)
To permit the unit to cool even at low ambient temperatures
Answer:
D
Explanation:
101)
101)
Compared to hot water heating coils, steam heating coils are:
A)
Physically smaller.
B)
More complicated in construction.
C)
Physically larger.
D)
Mostly plastic materials rather than metal.
Answer:
A
Explanation:
102)
102)
The ductwork connections for a rooftop packaged unit are typically:
A)
On the top of the unit.
B)
On the bottom of the unit.
C)
On the side of the unit.
D)
Not used because they do not connect to ductwork.
Answer:
B
Explanation:
27
103)
103)
Large rooftop package AC units often use ________ to help draw in fresh air to meet code
requirements and to cool if temperature and humidity permit.
A)
airflow
B)
low pressure
C)
enthalpy
D)
an economizer
Answer:
D
Explanation:
104)
104)
Which areas of a large office building have the most constant cooling load?
A)
The south–facing exterior parts of the building
B)
The interior parts of the building
C)
The north–facing exterior parts of the building
D)
The east– and west–facing exterior parts of the building
Answer:
B
Explanation:
105)
105)
Residential air conditioning refers to air conditioning applied to:
A)
Retail stores.
B)
Industrial plants.
C)
Office buildings.
D)
Private household residences.
Answer:
D
Explanation:
106)
106)
What is a chiller?
A)
A refrigeration system designed to cool refrigerant
B)
A refrigeration system designed to cool liquid
C)
A refrigeration system used to cool walk–in freezers
D)
A refrigeration system designed to cool beer mugs
Answer:
B
Explanation:
28
107)
107)
PTAC units are:
A)
Partial temporary air–conditioning units.
B)
Packaged terminal air–conditioning units.
C)
Partial trajectory air–conditioning units.
D)
Packaged temporary air–conditioning units.
Answer:
B
Explanation:
108)
108)
In most commercial air handlers:
A)
The blower draws the air across the coil.
B)
The air passes through the unit twice: once for the blower and another time for the coil.
C)
The blower and coil are located in separate component parts of the system.
D)
The blower forces the air across the coil.
Answer:
A
Explanation:
109)
109)
A significant contribution to the cooling load for the interior portion of a commercial office
building is:
A)
The heat gain through the partition walls.
B)
The heat gain through the floors on a multistory building.
C)
The solar heat gain.
D)
The heat generated by lighting.
Answer:
D
Explanation:
110)
110)
What type of compressors are most commonly used in rooftop packaged units?
A)
Hermetic reciprocating or hermetic scroll compressors
B)
Semihermetic scroll or semihermetic rotary compressors
C)
Open–type centrifugal and open–type screw compressors
D)
Hermetic rotary and hermetic centrifugal compressors
Answer:
A
Explanation:
29
111)
111)
What happens if the steam trap at the outlet of a heating coil is stuck in the closed position?
A)
Steam flow through the coil will be excessive and air temperatures will be too high.
B)
Steam flow through the coil will stop and the air temperature will be too low.
C)
The steam coil will flood with condensate water.
D)
The boiler will stop producing steam.
Answer:
B
Explanation:
112)
112)
Technicians should know that fan speed is directly related to the amount of air a fan can move;
therefore, doubling the fan speed will ________ the amount of air flow.
A)
triple
B)
double
C)
increase by 10 percent
D)
increase by 25 percent
Answer:
B
Explanation:
113)
113)
Three types of fan blades used with centrifugal fans include:
A)
Straight, forward–curved, and right angle.
B)
Straight, right angle, and airfoil.
C)
Forward–curved, backward–curved, and backward–curved airfoil.
D)
Concentric, isentropic, and exothermal.
Answer:
C
Explanation:
114)
114)
Hot water heating coils should be piped:
A)
For parallel flow so that the warmest water meets the coldest air.
B)
For counter flow so that the warmest water meets the warmest air.
C)
With iron pipe for durability and strength.
D)
With PVC pipe to take advantage of PVC’s natural insulating ability.
Answer:
B
Explanation:
30
115)
115)
Immediately after making adjustments to an air handler, it is important to check:
A)
The outdoor ambient temperature.
B)
The return air temperature.
C)
The compressor shell temperature.
D)
The blower motor amp draw under load.
Answer:
D
Explanation:
116)
116)
Which of the following filters would be appropriate for a large industrial air handler?
A)
A 16″ × 20″ × 1″ panel filter
B)
An electronic air cleaner
C)
A washable hogs–hair filter
D)
A large fiberglass roll filter
Answer:
D
Explanation:
117)
117)
What is the difference between a viscous impingement filter and a standard filter?
A)
Viscous filters are tested for viscosity.
B)
Viscous filters are specifically for filtering oil.
C)
Viscous filters use an electrical charging system.
D)
Viscous filters are treated with a sticky substance to trap and hold dirt.
Answer:
D
Explanation:
118)
118)
The two main types of fan drives are:
A)
Serpentine belt and chain drive.
B)
Planetary gear drive and worm gear drive.
C)
Direct drive and belt drive.
D)
Magnetic drive and hydrodrive.
Answer:
C
Explanation:
31
119)
119)
In order to double fan RPM, the motor horsepower:
A)
Must increase by a factor of 8 (2 × 2 × 2).
B)
Will not be affected by the fan RPM.
C)
Must also double.
D)
Must increase by a factor of 4 (2 × 2).
Answer:
A
Explanation:
120)
120)
If the air inlet to a centrifugal fan is restricted:
A)
The fan motor current draw will increase.
B)
The fan motor current draw will decrease.
C)
The fan RPM will decrease.
D)
The fan operation will be unaffected.
Answer:
B
Explanation:
121)
121)
The advantage of the backward–curved centrifugal fan over the forward–curved centrifugal fan is
that:
A)
Backward–curved fans operate at lower RPM.
B)
Backward–curved centrifugal fans are well suited for small airflow quantities.
C)
Backward–curved fans are normally quieter in operation.
D)
Backward–curved fans are non–overloading.
Answer:
D
Explanation:
122)
122)
Axial fans are commonly used on applications where:
A)
Small volumes of air are required at a relatively high static pressure.
B)
Large volumes of air are required at a relatively high static pressure.
C)
Reverse loading of the blower bearings is desired.
D)
Large volumes of air are required at a relatively low static pressure.
Answer:
D
Explanation:
32
123)
123)
After making a belt or pulley adjustment to a belt drive fan, it is crucial to check:
A)
The resistance of the motor windings.
B)
The resistance of the motor winding insulation with a megohm meter.
C)
The fan motor operating current reading.
D)
The level of the blower housing.
Answer:
C
Explanation:
124)
124)
This type of fan is commonly used on condenser motors because it moves high volumes of air in
low static conditions.
A)
Forward–curved centrifugal
B)
Tube axial
C)
Backward–curved centrifugal
D)
Propeller
Answer:
D
Explanation:
125)
125)
What fan performance characteristics are shown on a typical fan curve?
A)
Horsepower, RPM, and reluctance
B)
Sound levels, bearing temperatures, and reluctance
C)
RPM, tip speed, and horsepower
D)
Pressure drop, efficiency, and horsepower
Answer:
D
Explanation:
126)
126)
When low–voltage thermostat wire is run through the roof to the conditioned space, the
thermostat should then be located as close to the ________ as possible.
A)
mechanical room
B)
return air
C)
electrical service panel
D)
fresh air intake
Answer:
B
Explanation:
33
127)
127)
When installing a rooftop package unit, proper airflow through the condenser fan is critical. The
minimum free clearance air space above the condenser fan should be:
A)
60 in.
B)
12 in.
C)
48 in.
D)
72 in.
Answer:
A
Explanation:
128)
128)
Water and air leakage between the rooftop unit and the rooftop curb are prevented by:
A)
UL–rated duct tape applied over the outside of the curb.
B)
UL–rated duct tape applied to both the inside and outside of the curb.
C)
UL–rated duct tape applied from the inside of the curb.
D)
Gasket material between the curb and the unit.
Answer:
D
Explanation:
129)
129)
How can an installer accurately determine the weight for a particular rooftop unit?
A)
Balance the unit on top of an electronic charging scale.
B)
Look in the manufacturer’s installation instructions.
C)
Calculate the unit volume and divide that volume by the density of copper.
D)
An accurate estimate can be obtained by multiplying the unit volume times 2 lb.
Answer:
B
Explanation:
130)
130)
A crucial requirement whenever a rooftop installation is considered is:
A)
That rooftop units can only be installed on flat roofs.
B)
That a power drop can be made directly from the utility pole to the unit.
C)
To ensure that the unit cannot be seen from the front of the building.
D)
To ensure that the roof structure can support the weight of the equipment.
Answer:
D
Explanation:
34
131)
131)
When installing units requiring three–phase power, the voltages between any two power leads
must be:
A)
Within 15 percent of each other.
B)
Within 10 percent of each other.
C)
Within 3 percent of each other.
D)
Exactly the same.
Answer:
C
Explanation:
132)
132)
To ensure that the rafters or joists do not interfere with installation of the plenums on a
curb–mounted rooftop unit:
A)
The plenums are fabricated in place with the roof joists or rafters passing through them.
B)
The roof joists or rafters are cut out where the curb is installed.
C)
The roof curb must be installed diagonal to the roof joists or rafters.
D)
The roof curb must be square with the roof joists or rafters.
Answer:
D
Explanation:
133)
133)
What does the technician normally do when installing a gas vent on a rooftop packaged unit?
A)
A vent hood is needed only if the unit is installed inside.
B)
An approved double–wall vent is piped away from the unit to the side of the roof.
C)
The manufacturer–supplied hood is screwed onto the unit.
D)
An approved single–wall vent is piped at least 3 ft above the top of the unit.
Answer:
C
Explanation:
134)
134)
Why must the roof curb be installed square to the roof relative to the roof joists?
A)
To allow for proper condensate drainage
B)
To prevent water leakage
C)
To allow plenums to be located properly between the joists
D)
Code requirements
Answer:
C
Explanation:
35
135)
135)
To avoid cutting extra holes in the roof, power is normally provided to curb–mounted rooftop
units:
A)
Through the same conduit as the low–voltage control wiring.
B)
Directly from the power company’s utility pole.
C)
From underneath through the curb.
D)
Wirelessly using Wireless Power Connectors (WPC).
Answer:
C
Explanation:
136)
136)
The condensate drain on a rooftop unit:
A)
Must include a trap unless the unit has an integral trap.
B)
Does not require any type of drain line.
C)
Is normally run through the curb to an inside drain connection.
D)
Does not require a trap because of the short distance.
Answer:
A
Explanation:
137)
137)
Installation clearances for rooftop units are required:
A)
To isolate the equipment from materials that might be damaged by refrigerant leaks.
B)
To ensure that the weight of the unit does not rest directly on any roof trusses, beams, joists,
or rafters.
C)
To ensure the correct airflow through the condenser coil.
D)
To maintain a safe distance between the wiring and combustible materials.
Answer:
C
Explanation:
36
138)
138)
Rooftop units should not be installed in close proximity to exhaust vents or industrial processes
that create fumes because:
A)
The exhaust can be pulled into the unit’s outdoor air intake.
B)
The roof supports are weaker near the vents.
C)
The heat from the rooftop unit might cause down drafts.
D)
The exhaust might stain the side of the unit.
Answer:
A
Explanation:
139)
139)
What is the purpose of the hot and cold decks on a multizone system?
A)
The deck in use is called the hot deck.
B)
The hot deck is energized and the cold deck is not.
C)
They provide simultaneous hot and cold air.
D)
They provide places to stand that are warm and cool.
Answer:
C
Explanation:
140)
140)
The perimeter system is often used alongside a core system in:
A)
Interior spaces.
B)
Older buildings.
C)
Larger buildings.
D)
Single–story buildings.
Answer:
C
Explanation:
141)
141)
The perimeter of a large multistory high–rise building consists of:
A)
The areas around the outside of the building.
B)
The most important areas.
C)
The interior areas.
D)
The main floors.
Answer:
A
Explanation:
37
142)
142)
How does an energy–recovery wheel improve system efficiency?
A)
By transferring heat between the ventilation air and the exhaust air
B)
By moving some of the system refrigerant with a turbulator
C)
By keeping the evaporator clean
D)
By reducing the condenser head pressure
Answer:
A
Explanation:
143)
143)
A multizone system allows a wide range of temperatures in different zones supplied by a single
unit by:
A)
Piping air from cool zones to warm zones.
B)
Using multiple small compressors.
C)
Providing a blend of always–available heated and cooled air to any zone.
D)
Reheating cooled air using strip heaters.
Answer:
C
Explanation:
144)
144)
In perimeter applications using the variable–air–volume system, the primary air handler
provides:
A)
Variable volume and constant temperature.
B)
Constant volume and cooling only.
C)
Variable volume and heating only.
D)
Constant volume and constant temperature.
Answer:
A
Explanation:
145)
145)
In a single–zone constant–volume system, which floors only have provisions for cooling?
A)
Ground floors
B)
Every floor
C)
Belowground floors
D)
Intermediate floors
Answer:
D
Explanation:
38
146)
146)
In a single–zone constant–air–volume system, the amount of air moving through the air handler:
A)
Is proportional to the control signal.
B)
Is varied to meet the building load.
C)
Changes when the system switches from heating to cooling.
D)
Stays the same all the time.
Answer:
D
Explanation:
147)
147)
A unique feature of multizone and double–duct systems is that they:
A)
Can deliver conditioned air to different zones.
B)
Will fit in tight spaces.
C)
Can heat and cool at the same time using a single air handler.
D)
Operate more efficiently than most other systems.
Answer:
C
Explanation:
148)
148)
The amount of outside air introduced can be controlled using:
A)
An O2 sensor.
B)
An N2 sensor.
C)
A CO2 sensor.
D)
A CO sensor.
Answer:
C
Explanation:
149)
149)
A single–zone constant–air–volume system is best suited for conditioning:
A)
An area with a big variation in load.
B)
The perimeter of a building.
C)
A building that needs close control of several different areas.
D)
A building’s core area.
Answer:
D
Explanation:
39
150)
150)
Outside air is drawn into the building through:
A)
An outside air damper.
B)
Naturally occurring cracks in the building.
C)
A calibrated grille in the return air duct.
D)
A hole in the air handler cabinet.
Answer:
A
Explanation:
151)
151)
What do air–quality sensors measure?
A)
Ozone and NOx levels
B)
CO2, enthalpy, and humidity
C)
O2 and NOx levels
D)
Temperature, velocity, and pressure
Answer:
B
Explanation:
152)
152)
What temperature sensors are used with a commercial air handler?
A)
Mixed air, supply air, and preheat sensors
B)
Preheat and postheat sensors
C)
Preheat, low–temperature, and high–temperature sensors
D)
Mixed air and separated air sensors
Answer:
A
Explanation:
153)
153)
In a direct digital control system the primary controller is the:
A)
Wheatstone bridge.
B)
Voltage amplifier.
C)
Bleed–type thermostat.
D)
HVACR computer.
Answer:
D
Explanation:
40