Mechanical Engineering Unit 61 To 70 Why Would Temperature Differential Defrost System Not Complete The Defrost Cycle There

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page-pf1
154)
154)
Why would a temperature-differential defrost system NOT complete the defrost cycle?
A)
There is a refrigerant undercharge.
B)
The fan blows warm air across the coil.
C)
There is too much heat available during defrost.
D)
The system defrosts too frequently.
Answer:
A
Explanation:
155)
155)
Why would the timer on a time-temperature defrost system reset?
A)
The system did not trigger the switch on the board.
B)
The timing circuit starts a new countdown.
C)
The defrost temperature is not cold enough.
D)
The defrost temperature is not warm enough.
Answer:
C
Explanation:
156)
156)
How do you check system performance during the heating cycle?
A)
Recharge the system with the correct amount of refrigerant.
B)
Consult system pressure charts for indoor and outdoor temperatures.
C)
Recharge the system using a heating performance check chart.
D)
Attach a low-pressure gauge to the vapor line.
Answer:
B
Explanation:
157)
157)
Why do heat pumps require a high amount of servicing?
A)
The components are prone to corrosion.
B)
They operate at intense speeds.
C)
They clog frequently.
D)
They operate throughout the year.
Answer:
D
Explanation:
41
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158)
158)
Which of the following is a step in checking a system's defrost cycle?
A)
Set the defrost thermostat to a higher temperature.
B)
Short the test pins together.
C)
Turn off the pressure switch.
D)
Clear the area around the outdoor coil.
Answer:
B
Explanation:
159)
159)
Why would the compressor run longer when system demand is not high?
A)
The system was precharged with too much refrigerant.
B)
The system is clogged with debris.
C)
The system registers a below normal operating pressure.
D)
The system does not have the correct amount of refrigerant.
Answer:
D
Explanation:
160)
160)
Why must you cover the coils when testing the heat pump in warm weather?
A)
To increase the amount of heat delivered to the system
B)
To reduce the amount of heat lost from the system
C)
To prevent the heat pump from overloading the compressor
D)
To trigger the temperature valve to release excess pressure
Answer:
C
Explanation:
161)
161)
How can you reduce the chances of check valves getting stuck?
A)
Lubricate the check valves.
B)
Use a flapper-style check valve.
C)
Install backup check valves.
D)
Use a ball-style check valve.
Answer:
D
Explanation:
42
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162)
162)
How do you position a reversing valve when replacing it?
A)
Place the reversing valve with the main piston in a horizontal position.
B)
Place the reversing valve with the main piston in a vertical position.
C)
Place the reversing valve higher than the pilot valve.
D)
Place the reversing valve level with the pilot valve.
Answer:
A
Explanation:
163)
163)
How can you determine the amount of airflow in a heat pump?
A)
Compare rate of airflow against external static pressure.
B)
Measure air temperature, amperage, and voltage, and calculate the airflow.
C)
Align the thermometer with the heat strips and note the temperature.
D)
Operate the blower and read the external temperature.
Answer:
B
Explanation:
164)
164)
Which of the following techniques releases a stuck check valve?
A)
Moving a magnet along the middle or end of the valve
B)
Adding refrigerant to shift the position of the valve
C)
Switching cycles to create or release pressure on the valve
D)
Purging the system to shift the position of the valve
Answer:
A
Explanation:
43
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165)
165)
What is a bonded roof?
A)
Bonding is insurance that the roofing contractor provides the building owner to cover water
damage if the roof were to leak.
B)
A bonded roof is a metal roof that has been electrically grounded.
C)
Bonding is a process used to attach the roofing materials to the substrate they rest upon.
D)
Bonding is a form of roof construction that uses heat to form a single continuous sheet of
material over the roof surface.
Answer:
A
Explanation:
166)
166)
Why is the cost of owning a green building often less than the cost of owning a conventionally
constructed building?
A)
Green colors reflect excess heat away from the building.
B)
Green buildings typically cost less per square foot to construct.
C)
The utility and maintenance costs are less.
D)
Mortgage rates for green construction are subsidized by the federal government.
Answer:
C
Explanation:
167)
167)
To increase the strength and durability of the floor, plywood decking is installed:
A)
With the end joints aligned.
B)
With the end joints offset.
C)
With the length of the plywood parallel to the floor joists.
D)
Diagonal to the floor joists.
Answer:
B
Explanation:
44
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168)
168)
To avoid falling, when working above a sheetrock ceiling technicians should:
A)
Walk quickly whenever it is necessary to walk directly on the sheetrock.
B)
Step only on the sheetrock between the ceiling joists.
C)
Walk slowly whenever it is necessary to walk directly on the sheetrock.
D)
Step only on the ceiling joists.
Answer:
D
Explanation:
169)
169)
The standard ceiling height in a single family residence is:
A)
10 ft.
B)
7 ft.
C)
8 ft.
D)
12 ft.
Answer:
C
Explanation:
170)
170)
Fire dampers are typically required in:
A)
All residential buildings.
B)
All buildings that have ductwork.
C)
The chimney of all residential fireplaces.
D)
All commercial buildings with ductwork passing through firewalls.
Answer:
D
Explanation:
171)
171)
Which of the following materials has an the highest R value per inch of thickness?
A)
Loose-fill fiberglass
B)
Rigid foam board
C)
Batt and blanket rock wool
D)
Spray-on cellulose fiber
Answer:
B
Explanation:
45
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172)
172)
Which of the following are common materials used for insulation in residential construction?
A)
Cement, asbestos, and gypsum
B)
Thermoplastic, PVC, and ABS
C)
PVC, asbestos, and vermiculite
D)
Fiberglass, cellulose, and foam
Answer:
D
Explanation:
173)
173)
What are post tension cables, reinforcing rods, and wire mesh used for in construction?
A)
Reinforcing residential roofing
B)
Reinforcing light frame construction
C)
Reinforcing concrete
D)
Reinforcing asphalt driveways
Answer:
C
Explanation:
174)
174)
What does the phrase "dried in" mean?
A)
Construction has been halted due to dry weather.
B)
Enough dry weather has occurred to allow the site to be graded to begin construction.
C)
The house is weatherproof with exterior walls, roof, windows, and doors.
D)
All the paint and caulk on the interior walls and trim has dried to the touch, allowing
registers and grilles to be installed.
Answer:
C
Explanation:
175)
175)
What does LEED certification mean?
A)
Lifetime Environmental Engineering Design examines the environmental impact of the
building over its lifetime.
B)
Litigation Equipped Engineering Design protects building owners from lawsuits arising
from indoor air quality issues.
C)
Lower Environmental Energy Displacement certifies that a building operates at the lowest
energy level possible.
D)
Leadership in Energy Efficiency and Environmental Design (LEED) is a green building
standards certification.
Answer:
D
Explanation:
46
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176)
176)
What part of a home most readily loses or gains interior heat?
A)
Exterior walls
B)
The floor
C)
Crawlspaces
D)
The ceiling
Answer:
D
Explanation:
177)
177)
The air-conditioning system rough-in work normally begins:
A)
After the house is completely dried in.
B)
After all the interior walls are complete.
C)
After the house is framed.
D)
After most of the interior finish work is completed.
Answer:
A
Explanation:
178)
178)
The four major phases of construction in order are:
A)
Foundation, framing, dried in, and finish work.
B)
Dried in, foundation, framing, and finish work.
C)
Foundation, dried in, framing, and finish work.
D)
Dried in, framing, foundation, and finish work.
Answer:
A
Explanation:
179)
179)
The goals of most sustainable energy codes and standards are:
A)
Improve construction efficiency, reduce cost, and reduce construction time.
B)
Improve building efficiency, reduce waste, and reduce economic impact.
C)
Improve financial efficiency, reduce construction delay, and reduce economic impact.
D)
Improve energy efficiency, reduce waste, and reduce environmental impact.
Answer:
D
Explanation:
47
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180)
180)
The IGCC acts as an overlay on other existing codes, including the provisions of the ________ as a
baseline.
A)
IECC
B)
IGCC
C)
LEED
D)
EICC
Answer:
A
Explanation:
181)
181)
In an effort to reduce environmental impact during and after construction, reduce construction
waste, and make buildings more efficient, the state of California passed the:
A)
CALGreen Code.
B)
Montreal Protocol.
C)
International Energy Conservation Code.
D)
LEED Rating System.
Answer:
A
Explanation:
182)
182)
Levels of LEED building certification include:
A)
Silver, Gold, and Platinum.
B)
Bronze, Silver, and Gold.
C)
Tin, Copper, and Bronze.
D)
Silver, Gold, and Emerald.
Answer:
A
Explanation:
183)
183)
An example of sustainable material use would be:
A)
Using extra supports to ensure structural strength and long life.
B)
Using synthetic building materials to minimize tree cutting.
C)
Using recycled and recovered waste materials for construction.
D)
Using only new building materials that were naturally grown.
Answer:
C
Explanation:
48
page-pf9
184)
184)
The LEED program standards are developed by:
A)
USGBC - United States Green Building Council.
B)
NHAB - National Association of Home Builders.
C)
DOE - Department of Energy.
D)
EPA - Environmental Protection Agency.
Answer:
A
Explanation:
185)
185)
According to the U.S. Green Building Council (USGBC), buildings in the United States are
responsible for ________ percent of CO2 emissions, 40 percent of the total energy consumption,
and 13 percent of all water consumption.
A)
39
B)
38
C)
40
D)
30
Answer:
A
Explanation:
186)
186)
The 2010 California Green Building Standards Code is a code with ________ requirements for new
residential and nonresidential buildings.
A)
limiting
B)
mandatory
C)
restrictive
D)
optional
Answer:
B
Explanation:
187)
187)
What is the name of the EPA program for encouraging the use of energy-efficient products and
practices?
A)
Green Building Initiative
B)
BTP
C)
Energy Star
D)
LEED
Answer:
C
Explanation:
49
page-pfa
188)
188)
What is the purpose of the Department of Energy's Building Technologies Program (BTP)?
A)
To achieve a 30 percent reduction in energy use in residential and commercial building
codes
B)
To develop technologies for producing less-expensive construction techniques
C)
To develop technologies for building homes faster
D)
To teach young architects about standard building technologies
Answer:
A
Explanation:
189)
189)
USGBC is a cooperating sponsor in the development of the two primary baseline building energy
codes. One is ANSI/ASHRAE/USGBC/IES Standard 189.1-2009. What is the other?
A)
GBAP - Green Building Assessment Protocol
B)
IGCC - International Green Construction Code
C)
IRCC - International Residential construction code
D)
NAHB National Green Building Standard
Answer:
B
Explanation:
190)
190)
The National Association of Home Builders' Green Building Standard applies to:
A)
All types of construction.
B)
Industrial and commercial properties and buildings.
C)
Single-family homes, apartments, and condos.
D)
Multiuse projects, high rise construction, and commercial development.
Answer:
C
Explanation:
50
page-pfb
191)
191)
How can you lower the temperature at which evaporation takes place?
A)
Decrease the pressure on the high side of the pump.
B)
Reduce the pressure on the low side of the system.
C)
Raise the pressure on the low side of the pump.
D)
Add more refrigerant into the pump.
Answer:
B
Explanation:
192)
192)
The heat source for an air-source heat pump is:
A)
The air inside the house.
B)
The air outside the house.
C)
The water in the water loop.
D)
Electric strip heat.
Answer:
B
Explanation:
193)
193)
When is the outdoor metering device bypassed?
A)
The heating cycle
B)
Both the cooling and heating cycles
C)
The cooling cycle
D)
When it is plugged
Answer:
C
Explanation:
194)
194)
Why are both lines of a mini-split system insulated?
A)
Because the entire unit is outdoors
B)
Because they do not have any ductwork
C)
Because there is only one metering device
D)
Because it can connect up to 8 sections
Answer:
C
Explanation:
51
page-pfc
195)
195)
How is the COP rating different from the HSPF?
A)
HSPF takes data from multiple weather conditions.
B)
Only the HSPF measures heating and cooling units.
C)
Only the COP measures defrost.
D)
COP takes data from multiple weather conditions.
Answer:
A
Explanation:
196)
196)
Which of the following is the correct order of the flow in the cooling cycle of an air-source heat
pump?
A)
Reversing valve, indoor coil, outdoor coil, outdoor TEV, compressor
B)
Compressor, reversing valve, indoor coil, outdoor TEV, outdoor coil, reversing valve
C)
Compressor, reversing valve, outdoor coil, indoor TEV, indoor coil, reversing valve
D)
Outdoor TEV, outdoor coil, reversing valve, compressor, reversing valve, indoor coil
Answer:
C
Explanation:
197)
197)
One principle that makes heat pump operation possible is:
A)
The temperature at which a material boils depends on its pressure.
B)
Heat will flow up hill when subjected to a strong magnetic field.
C)
Moving heat quickly through a cold object will create thermal induction, drawing in heat
from the colder surroundings.
D)
Air velocity over a coil will create friction, raising the temperature of the coil.
Answer:
A
Explanation:
52
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198)
198)
How does the liquid turn back into vapor during the heating cycle?
A)
The indoor check valve is opened to allow heat in.
B)
Heat is added in the condenser.
C)
Heat is taken from the outside air.
D)
The indoor check valve closes to keep heat in.
Answer:
C
Explanation:
199)
199)
Heat pump A has a SEER rating of 16 and an HSPF rating of 7. Heat pump B has a SEER rating of
14 and an HSPF rating of 9. Which heat pump cools more efficiently?
A)
Heat pump A
B)
Heat pump B
C)
They are about the same heating efficiency by the time both the SEER and HSPF are
considered.
D)
Neither the SEER nor the HSPF can determine which heat pump heats more efficiently.
Answer:
A
Explanation:
200)
200)
The heat source for a heat pump is:
A)
Always water.
B)
The warm medium that the condenser rejects heat into.
C)
The cool medium that the evaporator draws heat out of.
D)
Always air.
Answer:
C
Explanation:
53
page-pfe
201)
201)
How is heat pump Heating Seasonal Performance Factor, HSPF, calculated?
A)
HSPF is the ratio of heat output divided by heat input averaged for the entire heating
season.
B)
HSPF is a measure of heating BTU per watt averaged for the entire heating season.
C)
HSPF is the ratio of heat output divided by heat input measured at one particular condition.
D)
HSPF is a measure of heating BTU per watt measured at one particular condition.
Answer:
B
Explanation:
202)
202)
What is the most common form of auxiliary heat used in heat pumps?
A)
Electric boiler
B)
Gas furnace
C)
Oil furnace
D)
Electric resistance strip heat
Answer:
D
Explanation:
203)
203)
Why is supplemental heat the second stage of heating and not the first?
A)
Because the thermostat won't let it energize right away
B)
Because electric strip heaters turn on and off constantly
C)
Because electric strip heaters produce heat less efficiently
D)
Because auxiliary heat is inexpensive
Answer:
C
Explanation:
204)
204)
When does the temperature differential initiate the defrost cycle?
A)
When the coil and air temperature difference increases for a prolonged period of time
B)
When there is any frost on the coil
C)
When the difference between the coil and outdoor air is constant
D)
When the air temperature drops below the coil temperature
Answer:
A
Explanation:
54
page-pff
205)
205)
When is the Y terminal energized on most heat pump thermostats?
A)
Both first-stage heating and cooling
B)
In first stage heating only
C)
In first stage cooling only
D)
Anytime the system is energized
Answer:
A
Explanation:
206)
206)
How are the indoor sections of mini-split heat pump systems normally installed?
A)
A large hole must be cut in an outside wall and extra framing added to support the unit.
B)
They are mounted on the ceiling or hung on a wall.
C)
The indoor section is installed in an attic or basement and ducted to the conditioned space.
D)
They are mounted in a window with the refrigerant lines running out the back.
Answer:
D
Explanation:
207)
207)
One big advantage of air-to-water heat pumps over air-to-air heat pumps is:
A)
More technicians are familiar with them.
B)
They are less expensive.
C)
They do not require electric strip heat in defrost.
D)
They are easier to install.
Answer:
C
Explanation:
208)
208)
On a time temperature defrost control, what determines the amount of time before the defrost
cycle starts?
A)
Coil temperature
B)
Coil pressure drop
C)
Compressor operating time
D)
Outdoor temperature
Answer:
C
Explanation:
55
page-pf10
209)
209)
In a dual-fuel heat pump, what operates when second-stage heat calls?
A)
The furnace starts and the heat pump shuts off.
B)
The heat pump starts and the furnace shuts off.
C)
The electric heat strips are energized to supplement the furnace.
D)
Both the heat pump and the furnace operate.
Answer:
A
Explanation:
210)
210)
What is the purpose of the discharge line thermostat?
A)
To shut off the compressor if the superheat gets too low
B)
To keep the discharge air from exceeding 200°F in the heating mode
C)
To prevent the compressor from operating at temperatures that will cause oil breakdown
and loss of lubrication
D)
To ensure that the discharge air is always warm in the heating cycle
Answer:
C
Explanation:
211)
211)
On a dual-fuel heat pump, why does the heat pump outdoor unit normally shut off when the
furnace comes on?
A)
The hot air leaving the furnace would cause very high head pressures on the heat pump.
B)
With both operating, the hot supply air causes customer complaints.
C)
The air can only go across one appliance at a time.
D)
The combined amp draw of the furnace and heat pump is too high.
Answer:
A
Explanation:
212)
212)
When is the air coil in a water-source heat pump the acting evaporator?
A)
In the cooling cycle
B)
In the heating cycle
C)
In the defrost cycle
D)
Only when the unit is operating
Answer:
A
Explanation:
56
page-pf11
213)
213)
What efficiency advantage do water-source heat pump systems have over air-source heat pump
systems?
A)
Water is a more efficient refrigerant than either R-22 or R-410A.
B)
It takes less horsepower to pump water than air.
C)
Water is a more efficient heat-transfer medium, and water temperatures are moderated by
the earth.
D)
Heat has more affinity for water than air.
Answer:
C
Explanation:
214)
214)
Why do water-source units not require suction line accumulators or charge compensators?
A)
The ground loop stores refrigerant, eliminating the need for line accumulators and charge
compensators.
B)
The water-source unit's capacity is less variable because the water being supplied to it must
be moderate in temperature.
C)
The fact that water and refrigerant always travel in opposite directions eliminates the need
for line accumulators and charge compensators.
D)
The charge for water source systems is less critical.
Answer:
B
Explanation:
215)
215)
Which of the following systems is most suitable where a pond or lake is located fairly close to the
building?
A)
Water-to-air closed loop system with loop sunk in pond
B)
Air-to-air system with outdoor unit located near the water
C)
Air-to-water system using the pond as a buffer tank
D)
Water-to-air open loop system using the pond water
Answer:
A
Explanation:
57
page-pf12
216)
216)
Where are packaged water-source heat pumps normally located?
A)
In the garage
B)
Outside close to the building power entrance
C)
Inside the building
D)
Outside near the water source
Answer:
C
Explanation:
217)
217)
Some water-source heat pumps contain a separate coaxial coil for heating domestic hot water.
The heat for the domestic hot water comes from:
A)
Using the water heating coil instead of the loop in cooling.
B)
Subcooling the liquid leaving the condenser.
C)
A submersion-style electric heater.
D)
De-superheating the hot gas leaving the compressor.
Answer:
D
Explanation:
218)
218)
A geothermal heat pump system:
A)
Uses the ground as a heat source in heating and a heat sink in cooling.
B)
Uses the ground as a heat source in both heating and cooling.
C)
Uses the ground as a heat sink in both heating and cooling.
D)
Uses the ground as a heat sink in heating and a heat source in cooling.
Answer:
A
Explanation:
219)
219)
Water and refrigerant flow through the coaxial coil:
A)
At different times depending on the cycle.
B)
In opposite directions.
C)
Together and are separated at the end by a separator tube.
D)
In the same direction.
Answer:
B
Explanation:
58
page-pf13
220)
220)
What does the pressure drop across the coaxial coil tell the technician?
A)
The amount of refrigerant charge
B)
A pressure drop across the coaxial coil indicates a restriction in the water loop.
C)
A pressure drop across the coaxial coil indicates a refrigerant restriction.
D)
The water flow through the system
Answer:
D
Explanation:
221)
221)
What code restrictions can prevent using an open-loop geothermal system?
A)
Some states have bans on any type of geothermal system.
B)
Some states require all discharged water to stay on the owner's property.
C)
Geothermal systems typically are not very efficient.
D)
Patent and copyright laws often prohibit the use of open-loop systems.
Answer:
B
Explanation:
222)
222)
Which of the following is a critical operating parameter that should always be checked on
water-source systems?
A)
Discharge pressure
B)
Water flow
C)
TEV adjustment
D)
Suction pressure
Answer:
B
Explanation:
223)
223)
Split-system heat pumps normally come with enough refrigerant for:
A)
The outdoor unit and indoor unit.
B)
The outdoor unit only.
C)
The outdoor unit, indoor unit, and an assumed length of lines.
D)
A holding charge, just enough to keep air out.
Answer:
C
Explanation:
59
page-pf14
224)
224)
What type of antifreeze solutions may be used in ground loops?
A)
Preferably ethylene glycol
B)
Low toxicity
C)
Any antifreeze that will extend the freezing point down to -35°F
D)
A brightly colored antifreeze solution should be used to make it visible in ground water.
Answer:
B
Explanation:
225)
225)
How can the water flow through a geothermal system be determined?
A)
By reading the display on the heat pump touchscreen control
B)
By using an clamp-on water flow meter
C)
By comparing the waterflow to the refrigerant pressure chart
D)
By measuring the pressure drop across the coaxial coil and comparing it to the
manufacturer's chart
Answer:
D
Explanation:
226)
226)
How can debris be flushed from a newly installed ground loop?
A)
By temporarily connecting the purge unit.
B)
By adding low-toxicity antifreeze to the system.
C)
By running water through the loop before connecting it to the system.
D)
By running water through the loop after connecting it to the system.
Answer:
C
Explanation:
227)
227)
What type of heat exchanger coil is best suited for water-source heat pumps using an open-loop
well system?
A)
Cupronickel
B)
Steel
C)
Cast iron
D)
Copper
Answer:
A
Explanation:
60

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