233)
233)
Two types of takeoff fittings available for sheet metal duct include:
A)
Adhesive–backed flanges, trunk ducts with knock–outs.
B)
Dovetail, weld–on stubs.
C)
Weld–on stubs, preformed stubs.
D)
Dove tail, adhesive–backed flanges.
Answer:
D
Explanation:
234)
234)
As a technician‘s rule of thumb, fan speed should not be adjusted more than ________ percent
above or below manufacturer’s specifications.
A)
25
B)
50
C)
10
D)
Do not adjust the fan speed.
Answer:
C
Explanation:
235)
235)
Manufacturer’s troubleshooting charts typically ask:
A)
That the reader have at least a master’s degree in mechanical engineering.
B)
The technician to replace parts in an established hierarchy.
C)
Yes/no questions to determine the cause.
D)
Open–ended questions with no specific answer.
Answer:
C
Explanation:
61
236)
236)
The manufacturer’s data on a split AC system indicates that the normal temperature drop should
be 15°F at the current operating conditions. If the evaporator entering air temperature is 80°F and
the leaving air temperature is 55°F, the technician knows that the system:
A)
Most likely is overcharged because it is cooling better than it is supposed to.
B)
Most likely has low air flow because of the higher–than–normal temperature drop.
C)
Most likely has higher than normal airflow because of the higher–than–normal temperature
drop.
D)
Is working great, even better than manufacturer’s specifications.
Answer:
B
Explanation:
237)
237)
How is the subcooling of an air–conditioning system affected by a low refrigerant charge?
A)
The subcooling will fluctuate erratically.
B)
The subcooling will be above normal.
C)
The subcooling will be below normal.
D)
The subcooling will not be affected by a low refrigerant charge.
Answer:
C
Explanation:
238)
238)
Three general areas of problems in air–conditioning systems include electrical problems,
mechanical problems, and:
A)
Airflow problems.
B)
Wiring problems.
C)
Undercharge problems.
D)
Communication problems.
Answer:
A
Explanation:
239)
239)
When a split AC system using a capillary tube is overcharged:
A)
The superheat will increase.
B)
The superheat will decrease.
C)
The compressor shell will get hot.
D)
The compressor shell will get cold.
Answer:
B
Explanation:
62
240)
240)
How is the subcooling of an air–conditioning system affected by a restriction in the liquid line?
A)
The subcooling will fluctuate erratically.
B)
The subcooling will not be affected by a low refrigerant charge.
C)
The subcooling will be below normal.
D)
The subcooling will be above normal.
Answer:
D
Explanation:
241)
241)
Carbon monoxide is formed:
A)
Anytime gas is burned.
B)
When the combustion air is at a high relative humidity.
C)
When the gas is not burning completely.
D)
When the flames are burning at a temperature exceeding the manufacturer’s recommended
maximum combustion temperature.
Answer:
C
Explanation:
242)
242)
Beginning in May 2013, the minimum AFUE rating for a new furnace in the southern part of the
United States is:
A)
90 percent.
B)
78 percent.
C)
80 percent.
D)
60 percent.
Answer:
C
Explanation:
243)
243)
What does a certification done by the Canadian Standards Association (CSA) signify?
A)
The furnace meets only Canadian standards.
B)
The equipment meets ANSI, UL, CSA America, or NSF standards.
C)
The equipment meets CSA and CSA America standards.
D)
The appliance fails to meet U.S. standards.
Answer:
B
Explanation:
63
244)
244)
Propane is:
A)
Lighter than air.
B)
Either lighter or heavier than air depending on the characteristics of the local gas.
C)
About the same density as air.
D)
Heavier than air.
Answer:
D
Explanation:
245)
245)
The approximate heating value of propane is:
A)
2,500 BTU per cubic foot.
B)
3,200 BTU per cubic foot.
C)
1,000 BTU per cubic foot.
D)
1,780 BTU per cubic foot.
Answer:
A
Explanation:
246)
246)
How does certification affect heating equipment in the United States?
A)
All gas appliances are exempt from certification but must be tested by an accredited testing
agency.
B)
Only electric heating equipment is required to have testing or certification by an accredited
testing agency.
C)
All heating equipment undergoes voluntary testing and certification by accredited testing
agencies.
D)
All heating equipment must be tested, certified, or listed by an accredited testing agency.
Answer:
D
Explanation:
247)
247)
The temperature where water vapor can begin condensing out of the air is the:
A)
Critical temperature.
B)
Dew point.
C)
Critical pressure.
D)
Specific humidity.
Answer:
B
Explanation:
64
248)
248)
What would the mixed air temperature be for a system with 20% outdoor air if the outdoor
temperature is 90°F and the return air temperature is 80°F?
A)
0.2 × 90°F =18°F; 0.8 × 80°F = 64°F; 18°F + 64°F = 82°F mixed air temperature
B)
(90°F + 80°F)/2 = 85°F mixed air temperature
C)
0.8 × 90°F =18°F; 18°F + 80°F = 98°F mixed air temperature
D)
(90°F + 80°F) × 0.4 = 68°F
Answer:
A
Explanation:
249)
249)
In the heating season, the comfort level can be improved at lower temperatures:
A)
By removing humidity and increasing air velocity.
B)
By removing humidity from the air.
C)
By increasing air velocity.
D)
By adding humidity to the air.
Answer:
D
Explanation:
250)
250)
What two pressures are created by air moving through the duct system?
A)
Supply pressure and return pressure
B)
Barometric pressure and atmospheric pressure
C)
Velocity pressure and static pressure
D)
Air pressure and friction pressure
Answer:
C
Explanation:
251)
251)
A balanced ventilation system:
A)
Can be installed with only a single central support in the middle.
B)
Can also provide heating and cooling.
C)
Uses a highly balanced blower wheel.
D)
Supplies and exhausts the same amount of air into the building.
Answer:
D
Explanation:
65
252)
252)
The formula for calculating the CFM needed to produce an air change is:
A)
CFM = (floor area × ceiling height)/8.
B)
CFM = (floor area × ceiling height)/60.
C)
CFM = floor area × ceiling height.
D)
CFM = (floor area × ceiling height)/12.
Answer:
B
Explanation:
253)
253)
How can negative room pressure create a hazardous situation in a house with combustion
appliances?
A)
The appliances may burn excessively hot.
B)
Combustion products can spill into the house.
C)
All the heat can be sucked out of the room through the vent.
D)
The gas pressure may be affected.
Answer:
B
Explanation:
254)
254)
A heat pipe increases the dehumidification effect of an air–conditioning coil:
A)
By piping water out of the air through a heated conduit.
B)
By cooling the entering air and reheating the leaving air.
C)
By heating the entering air and cooling the leaving air.
D)
By piping water out of the air through a cooled conduit.
Answer:
B
Explanation:
255)
255)
Variable refrigerant flow systems operate more efficiently with ________ installed outdoor unit
capacity by shifting the heating and cooling to where it is needed.
A)
full
B)
smaller
C)
larger
Answer:
B
Explanation:
66
256)
256)
Manufacturers recommend pressurizing VRF piping to ________ with nitrogen and performing a
24 hour standing leak test.
A)
500 600 psig
B)
300 400 psig
C)
200 300 psig
D)
400 500 psig
Answer:
A
Explanation:
257)
257)
Which of the following is NOT a type of indoor unit used on mini–split systems?
A)
Wall mount
B)
Crawl space
C)
Floor mount
D)
Ceiling suspended
Answer:
B
Explanation:
258)
258)
In what lengths are line sets normally available for residential split systems?
A)
5 to 25 ft
B)
50 to 150 ft
C)
15 to 50 ft
D)
25 to 100 ft
Answer:
C
Explanation:
259)
259)
Which of these installation steps listed is normally performed first?
A)
Commissioning
B)
Evacuating the system
C)
Charging the system
D)
Leak testing the system
Answer:
D
Explanation:
67
260)
260)
How is the refrigerant charge normally checked on air–conditioning systems that use a fixed
orifice expansion device?
A)
Adjust the charge to achieve a 40°F saturated evaporator temperature.
B)
Subcooling
C)
Feel to see if the suction line is cold and the liquid line warm.
D)
Superheat
Answer:
D
Explanation:
261)
261)
A 36,000 Btuh capacity air conditioner is installed in a house with a design heat gain of 26,500
Btuh. The extra capacity:
A)
Is acceptable because it is less than 1 ton larger than the design load.
B)
Will keep the system from dehumidifying the structure on warm days.
C)
Will save in operating cost because it will operate for shorter periods of time.
D)
Provides surplus capacity to ensure customer comfort.
Answer:
B
Explanation:
262)
262)
The majority of air leaks in sheet metal duct systems occur:
A)
Along the lengthwise seam in the duct.
B)
Around takeoffs on supply and return plenums.
C)
In the seams of adjustable elbows.
D)
At joints between ducts.
Answer:
B
Explanation:
68
263)
263)
The three methods most often used to quantify duct leakage rates are:
A)
Duct pressurization, duct draw down, and cross–sectional analysis.
B)
Leakage area, duct draw down, and cross–sectional analysis.
C)
Percentage of design flow, airflow per 100 sq ft of conditioned space, and leakage area.
D)
Cross–sectional analysis, duct pressurization, and leakage area.
Answer:
C
Explanation:
264)
264)
Hangers for fiberboard duct should be placed no further than every:
A)
6 ft.
B)
12 ft.
C)
5 ft.
D)
Fiberboard duct does not require hangers because it is self–supporting.
Answer:
A
Explanation:
265)
265)
Organizations that set safety standards for manufactured ductwork include:
A)
EPA and OSHA.
B)
ACCA and RSES.
C)
AHRI and HVAC Excellence.
D)
Underwriters Laboratories and the National Fire Protection Association.
Answer:
D
Explanation:
266)
266)
If an electrical load in a split–system air conditioner is not working, the technician must determine
if the problem is:
A)
Repairable or not repairable.
B)
In the line voltage or the low voltage.
C)
In the load itself or in the switches that control the load.
D)
Chronic or acute.
Answer:
C
Explanation:
69
267)
267)
The suction pressure on a split AC system that is running with an excessive evaporator heat load:
A)
Will be lower than normal.
B)
Is not affected by the load.
C)
Will be higher than normal.
D)
Will most likely pull into a vacuum.
Answer:
C
Explanation:
268)
268)
When working on a type of system that you have never seen before, you should:
A)
Methodically replace the parts until you locate the issue.
B)
Locate the manufacturer’s troubleshooting guide.
C)
Replace any electronic boards first.
D)
Assume that it works like other equipment you are familiar with.
Answer:
B
Explanation:
269)
269)
If an air–conditioning system is operating with an 80°F return air temperature and a 50°F supply
air temperature:
A)
The large temperature drop indicates excessive airflow.
B)
You should be happy the air is so cold.
C)
The system is operating correctly.
D)
The large temperature drop indicates the airflow is less than required.
Answer:
D
Explanation:
270)
270)
Soot forming in the heat exchanger can be caused by:
A)
The presence of coal tar in the gas.
B)
Too much air in the gasair mixture.
C)
Too much gas in the gasair mixture.
D)
Excessively high combustion temperatures.
Answer:
C
Explanation:
70
271)
271)
Why is carbon monoxide production undesirable in furnace operation?
A)
Carbon monoxide causes furnace inefficiency.
B)
Carbon monoxide is an inert substance.
C)
Carbon monoxide may block ventilation.
D)
Carbon monoxide is toxic.
Answer:
D
Explanation:
272)
272)
What is the difference between primary air and secondary air?
A)
Secondary air is only used if the primary air source is depleted.
B)
Primary air is used for the main burner and secondary air is used for the auxiliary burners.
C)
Primary air is used with natural gas and secondary air is used for LP gas.
D)
Primary air is mixed with the gas before ignition and secondary air is drawn in after
ignition.
Answer:
D
Explanation:
273)
273)
What component of an outdoor condenser unit is susceptible to damage from torch heat while
brazing?
A)
TXV valve
B)
Fan motor capacitor
C)
Low–pressure switch
D)
Valve Schrader stem
Answer:
D
Explanation:
71
274)
274)
Which of the following overcurrent protection devices would be appropriate for an
air–conditioning condensing unit whose rating plate says MAX FUSE or HACR CIRCUIT
BREAKER 35 AMPS?
A)
A 35 A HCAR circuit breaker
B)
A 35 A circuit breaker
C)
A 30 A time delay fuse
D)
No fuse or circuit breaker is necessary; but if one is used, it cannot exceed 35 A.
Answer:
A
Explanation:
275)
275)
What airflow adjustment should be made to increase the latent cooling capacity of an
air–conditioning system?
A)
Increase the airflow.
B)
Decrease the airflow.
C)
The latent cooling capacity is not affected by adjusting the system airflow.
D)
Set the airflow to the maximum available.
Answer:
B
Explanation:
276)
276)
A duct blaster is used:
A)
To install duct runs in approximately half the time of conventional methods.
B)
To install takeoffs onto plenums using high–velocity and percussive force.
C)
To measure the amount of air leakage in a duct system.
D)
To clean duct systems with high–velocity air.
Answer:
C
Explanation:
72
277)
277)
What are the two main types of duct–cleaning equipment being used?
A)
Units that use brushes and vacuum and units that use ultrasonic particle precipitation
B)
Large truck–mounted units and small portable units
C)
Ultraviolet units and ultrasonic particle precipitators
D)
Units that use high–velocity air and units that use sprayed cleaning compounds
Answer:
B
Explanation:
278)
278)
A manufactured air duct that meets all 15 UL 181 tests is classified as:
A)
A flexible air connector.
B)
A flexible air duct.
C)
Either a flexible air duct or a flexible air connector.
D)
Flexible air plenum.
Answer:
B
Explanation:
279)
279)
When ohming components on the system, it is important to:
A)
Turn on the power to the unit.
B)
Turn off the power to the unit.
C)
Work quickly before the power comes back on.
D)
Make sure the component is still wired in the circuit.
Answer:
B
Explanation:
280)
280)
Adding a little extra refrigerant over the amount recommended by the manufacturer:
A)
Reduces system capacity but slightly increases system efficiency.
B)
Increases system capacity slightly but reduces system efficiency.
C)
Reduces both system capacity and efficiency.
D)
Does not affect system capacity or efficiency, but provides a buffer against future refrigerant
loss and nuisance call backs.
Answer:
C
Explanation:
73
281)
281)
Agencies that set equipment standards and test equipment include:
A)
EPA and ASHRAE.
B)
DOE and EPA.
C)
CSA and AHRI.
D)
DOE and NIST.
Answer:
C
Explanation:
282)
282)
Combustion air for gas appliances should be:
A)
1 cu ft of combustion air for every cubic foot of gas.
B)
10 cu ft of combustion air per 1,000 BTU of firing rate.
C)
Recycled by piping the vent gases back into the combustion air intake.
D)
14 to 15 cu ft of combustion air per 1,000 BTU of firing rate.
Answer:
D
Explanation:
283)
283)
Using the CFM per 100 sq ft method, a 1,600 sq ft house leaking 120 CFM has a leakage rate of:
A)
1,600/120 = 13 CFM per 100 sq ft.
B)
120/16 = 7.5 CFM per 100 sq ft.
C)
1,600 – 120 = 1,480 CFM.
D)
1,600 + 120 = 1,720 CFM.
Answer:
B
Explanation:
284)
284)
Underwriters Laboratories standard 181 B covers:
A)
Methods of connecting and sealing metal duct.
B)
Methods of connecting and sealing flexible duct.
C)
Methods of connecting and sealing ductboard.
D)
Methods of connecting and sealing all types of duct.
Answer:
B
Explanation:
74
285)
285)
The majority of problems with residential air–conditioning systems are due to:
A)
Customer problems.
B)
Electrical problems.
C)
Refrigeration problems.
D)
Mechanical problems.
Answer:
B
Explanation:
286)
286)
The first electrical checks of a system that is not operating generally involve:
A)
Ohming out key components.
B)
Replacing all system capacitors.
C)
Adding refrigerant.
D)
Checking the power circuit to the equipment.
Answer:
D
Explanation:
287)
287)
LP gas is considered more hazardous than natural gas because:
A)
LP gas is poisonous.
B)
LP gas is flammable.
C)
LP tends to puddle in low areas but natural gas tends to dissipate.
D)
LP gas is flammable and poisonous.
Answer:
C
Explanation:
288)
288)
What is meant by the coil split?
A)
The part of an A–coil evaporator where the two halves are joined
B)
The dividing point in an evaporator between high–side pressure and low–side pressure
C)
An opening at the seam in the copper tubing
D)
The temperature difference between the coil operating temperature and the air passing over
the coil
Answer:
D
Explanation:
75