Indoor Temperature Control Quiz
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Depending on the outside temperature and the heating habits of residents, the heating requirements of rooms, apartments and entire buildings are constantly changing. Radiator thermostats and room temperature controller systems compensate for these fluctuations.
Know how Indoor temperature controlling works in this Indoor temperature control quiz
Questions and Answers
- 1.
The benefits of electric baseboard heating are that _________.
- A.
Each room can be controlled individually
- B.
They are inexpensive to install
- C.
They operate on a 24-V power supply
- D.
Both a and b
Correct Answer
D. Both a and bExplanation
Electric baseboard heating systems offer the benefits of individual room control and low installation costs. With this type of heating, each room can be controlled individually, allowing for personalized comfort and energy efficiency. Additionally, electric baseboard heaters are relatively inexpensive to install compared to other heating systems, making them a cost-effective option for many homeowners. Therefore, the correct answer is both a and b.Rate this question:
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- 2.
What would happen if the fan on an electric unit heater burned out?
- A.
The heater would remain energized until the fusible link melts.
- B.
The interlock switch would be de-energize the electric heater.
- C.
The unit will still heat the area, but it would take longer to do so.
- D.
Both a and b are possible.
Correct Answer
D. Both a and b are possible.Explanation
If the fan on an electric unit heater burned out, both options a and b are possible. Option a states that the heater would remain energized until the fusible link melts. This means that even though the fan is not working, the heater will continue to produce heat until the safety mechanism of the fusible link is triggered. Option b states that the interlock switch would de-energize the electric heater. This means that without the fan working, the interlock switch would detect the issue and shut off the power to the heater, preventing it from functioning. Therefore, both scenarios are possible outcomes if the fan on an electric unit heater burns out.Rate this question:
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- 3.
Technician "A" says that a fusible link can be jumped out temporarily to allow the customer to get heat until the next business day. Technician "B" says that if the fuses keep on blowing on an electric duct heater, the fan may be defective. Which of the following statements is correct?
- A.
Technician "A" is correct. Technician "B" is correct.
- B.
Technician "A" is correct. Technician "B" is incorrect.
- C.
Technician "A" is incorrect. Technician "B" is correct.
- D.
Technician "A" is incorrect. Technician "B" is incorrect.
Correct Answer
C. Technician "A" is incorrect. Technician "B" is correct.Explanation
Technician "A" is incorrect because jumping out a fusible link can be dangerous and is not a recommended solution. Technician "B" is correct because if the fuses keep blowing on an electric duct heater, it indicates a problem with the fan, which may be defective and causing excessive current draw.Rate this question:
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- 4.
If a duct-mounted electric heater is to be installed and it is discovered that the heater is too long to fit inside the duct (the duct is 10 inches high and 14 inches wide and the heater is 9½ inches high and 18 inches long), what can the technician do to properly complete the installation?
- A.
Install the heater at an angle.
- B.
Cut a slot in the duct work and allow the heater to protrude 4 inches out of the duct.
- C.
Return the heater to the supply house and obtain the correct size heater.
- D.
Cut the ends of the coils off the heater and increase the fan speed.
Correct Answer
C. Return the heater to the supply house and obtain the correct size heater.Explanation
The correct answer is to return the heater to the supply house and obtain the correct size heater because the given dimensions of the heater (9½ inches high and 18 inches long) are larger than the dimensions of the duct (10 inches high and 14 inches wide). Therefore, the technician cannot install the heater properly without the correct size that fits within the duct dimensions.Rate this question:
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- 5.
The resistance wire used in electric heating elements is usually _________.
- A.
Copper
- B.
Nickel steel
- C.
Nickel chromium
- D.
Aluminum
Correct Answer
C. Nickel chromiumExplanation
The resistance wire used in electric heating elements is usually made of nickel chromium. Nickel chromium alloys, such as Nichrome, have high electrical resistance and can withstand high temperatures without oxidizing or melting. This makes them ideal for heating elements as they can generate heat efficiently and withstand the harsh conditions of heating applications. Copper and aluminum have lower resistance and would not be suitable for heating elements, while nickel steel is not commonly used for this purpose.Rate this question:
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- 6.
Radiant heat is transferred by _________.
- A.
Ultraviolet rays
- B.
Infrared rays
- C.
Ionization
- D.
Refraction
Correct Answer
B. Infrared raysExplanation
Radiant heat is transferred by infrared rays. Infrared rays are a form of electromagnetic radiation that has longer wavelengths than visible light. When an object is heated, it emits infrared radiation, which can then be absorbed by other objects, causing them to heat up. Unlike ultraviolet rays, which have shorter wavelengths and can cause damage to the skin and eyes, infrared rays are responsible for the warmth we feel from sources such as the sun or a fire. Ionization and refraction are not methods of transferring radiant heat.Rate this question:
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- 7.
Electric baseboard heaters are classified as _________.
- A.
Natural draft convectors
- B.
Forced draft convectors
- C.
Forced draft conductors
- D.
Radiant heaters
Correct Answer
A. Natural draft convectorsExplanation
Electric baseboard heaters are classified as natural draft convectors because they operate by natural convection. They heat the air through a process where cool air enters the bottom of the heater, gets warmed up by the heating element, and then rises naturally to circulate the warm air throughout the room. There is no forced air or fan involved in this process. Hence, the correct classification for electric baseboard heaters is natural draft convectors.Rate this question:
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- 8.
Quartz and glass panel electric units are classified as _________.
- A.
Natural draft convectors
- B.
Forced draft convectors
- C.
Forced draft conductors
- D.
Radiant heaters
Correct Answer
D. Radiant heatersExplanation
Quartz and glass panel electric units are classified as radiant heaters because they emit heat through infrared radiation. Unlike natural draft convectors or forced draft convectors, which rely on convection to distribute heat, radiant heaters directly transfer heat to objects and people in their vicinity through electromagnetic waves. Therefore, the classification of quartz and glass panel electric units as radiant heaters is appropriate.Rate this question:
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- 9.
An electric heating unit in a duct system is classified as a _________.
- A.
Natural draft convector
- B.
Forced draft convector
- C.
Forced draft conductor
- D.
Radiant heater
Correct Answer
B. Forced draft convectorExplanation
An electric heating unit in a duct system is classified as a forced draft convector because it uses a fan or blower to force air over a heating element, which then heats up the air before it is distributed through the ducts. This type of heating system relies on the forced circulation of air to provide warmth and is commonly used in residential and commercial buildings.Rate this question:
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- 10.
A 10 Kw heating element, operating on rated 240 V, will have a Btu/h output of _________.
- A.
29,319
- B.
31,062
- C.
34,130
- D.
35,875
Correct Answer
C. 34,130Explanation
10,000 x 3.413 = 34,130Rate this question:
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- 11.
The limit switch is used on the electric element assembly to _________.
- A.
Start the unit if the thermostat malfunctions
- B.
Ensure that the fan stops when the unit cools down
- C.
Start the unit prematurely on a cold day
- D.
Open the circuit to the element if the furnace overheats
Correct Answer
D. Open the circuit to the element if the furnace overheatsExplanation
The limit switch is used on the electric element assembly to open the circuit to the element if the furnace overheats. This is important for safety reasons as it prevents the element from becoming too hot and potentially causing damage or starting a fire. By opening the circuit, the limit switch interrupts the flow of electricity to the element, effectively shutting it off and allowing the furnace to cool down.Rate this question:
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- 12.
A house is built on property whose soil is rich in uranium. The occupants of the house may _________.
- A.
Be exposed to radon gas
- B.
Be more susceptible to lung cancer
- C.
Smell the pungent odor of the radon
- D.
Both a and b
Correct Answer
D. Both a and bExplanation
The correct answer is both a and b. Since the soil is rich in uranium, there is a possibility of radon gas being present in the house. Radon gas is a radioactive gas that can seep into buildings from the ground. Exposure to radon gas is known to increase the risk of lung cancer. Therefore, the occupants of the house may be exposed to radon gas and be more susceptible to lung cancer.Rate this question:
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- 13.
The steps to aggressively controlling the contamination of indoor air would involve _________.
- A.
Locating and eliminating the source of contamination
- B.
Providing adequate ventilation
- C.
Providing methods for cleaning the air
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
The steps to aggressively controlling the contamination of indoor air would involve locating and eliminating the source of contamination, providing adequate ventilation, and providing methods for cleaning the air. This means that all of these actions are necessary in order to effectively control and reduce the contamination of indoor air. By identifying and removing the source of contamination, ensuring proper ventilation, and implementing cleaning methods, the indoor air quality can be improved and maintained at a healthier level.Rate this question:
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- 14.
Electronic air cleaners generally have _________.
- A.
Ionizing sections
- B.
Charcoal filters
- C.
Pre-filters
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
Electronic air cleaners generally have ionizing sections, charcoal filters, and pre-filters. Ionizing sections help to charge particles in the air, making them easier to capture. Charcoal filters are effective at removing odors and chemicals from the air. Pre-filters are used to capture larger particles, such as dust and pet dander, before they reach the main filtration system. Therefore, all of these components are commonly found in electronic air cleaners.Rate this question:
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- 15.
An extended surface filter (pleated type) _________.
- A.
Does not clog up as quickly as a standard filter
- B.
Is able to remove more dirt since the surface area is larger
- C.
Costs less than a standard filter
- D.
Both a and b
Correct Answer
D. Both a and bExplanation
An extended surface filter (pleated type) is able to remove more dirt since the surface area is larger and does not clog up as quickly as a standard filter. The pleated design increases the filter's surface area, allowing it to capture more particles and dirt. This extended surface also helps to distribute the airflow more evenly, reducing the likelihood of clogging. Therefore, the correct answer is both a and b.Rate this question:
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- 16.
One of the most common substances that is used as an absorber is _________.
- A.
Charcoal
- B.
Silica gel
- C.
Fiberglass
- D.
Foam rubber
Correct Answer
A. CharcoalExplanation
Charcoal is commonly used as an absorber due to its porous nature and high surface area. Its porous structure allows it to trap and retain various substances, such as gases, odors, and impurities, making it an effective absorber. Charcoal also has the ability to adsorb chemicals and toxins, making it useful in applications such as water and air filtration systems. Therefore, charcoal is a widely used substance for absorption purposes.Rate this question:
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- 17.
Humidification generally relates to the process of causing water to _________ into the air.
- A.
Condense
- B.
Evaporate
- C.
Be ionized
- D.
Be filtered
Correct Answer
B. EvaporateExplanation
Humidification is the process of adding moisture to the air. When water evaporates, it turns into water vapor and becomes part of the air. Therefore, the correct answer is "evaporate" as it accurately describes the process of causing water to become part of the air during humidification.Rate this question:
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- 18.
The controller for a humidifier, a humidistat, has a power element that is _________ sensitive.
- A.
Moisture
- B.
Light
- C.
Infrared
- D.
Temperature
Correct Answer
A. MoistureExplanation
The controller for a humidifier, a humidistat, has a power element that is moisture sensitive. This means that the humidistat is designed to detect the level of moisture in the air and adjust the operation of the humidifier accordingly. When the humidity level falls below a certain threshold, the humidistat will activate the humidifier to add moisture to the air. Conversely, when the humidity level rises above a certain threshold, the humidistat will deactivate the humidifier to prevent over-humidification.Rate this question:
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- 19.
Atomizing humidifiers discharge _________ into the air.
- A.
CO2
- B.
Electronic ions
- C.
Tri-valent oxygen
- D.
Tiny water droplets
Correct Answer
D. Tiny water dropletsExplanation
Atomizing humidifiers work by breaking down water into small particles or droplets, which are then dispersed into the air. These tiny water droplets increase the humidity in the surrounding environment. Therefore, the correct answer is "tiny water droplets".Rate this question:
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- 20.
In evaluating an air distribution system, the terminal units called the _________ are an important factor.
- A.
Electric baseboard and radiators
- B.
Evaporators and condenser
- C.
Registers and grills
- D.
Blower and damper
Correct Answer
C. Registers and grillsExplanation
Registers and grills are an important factor in evaluating an air distribution system because they are the terminal units through which the conditioned air is delivered to the occupied spaces. Registers and grills control the airflow and direction, ensuring proper distribution of air throughout the space. They also play a role in maintaining comfort by allowing occupants to adjust the flow of air and regulate the temperature. Therefore, the correct answer is registers and grills.Rate this question:
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- 21.
When adding a summer cooling system to an existing heating system, frequently a _________ must be added to the control circuit.
- A.
Thermocouple and limit switch
- B.
Glow coil and static pressure disc
- C.
Transformer and fan relay
- D.
Stack switch and CAD cell
Correct Answer
C. Transformer and fan relayExplanation
When adding a summer cooling system to an existing heating system, a transformer and fan relay must be added to the control circuit. This is because the transformer is responsible for stepping down the voltage from the power source to a level that is suitable for the control circuit. The fan relay, on the other hand, is used to control the operation of the fan in the cooling system, ensuring that it turns on and off as needed. By adding these components, the control circuit can effectively integrate both the heating and cooling systems, allowing for efficient and convenient operation.Rate this question:
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- 22.
When designing an all-weather system, the air distrubution system is designed around _________.
- A.
The cooling requirement
- B.
The heating requirement
- C.
Either heating or cooling requirements
- D.
Both heating and cooling requirements
Correct Answer
D. Both heating and cooling requirementsExplanation
When designing an all-weather system, the air distribution system needs to be able to provide both heating and cooling in order to maintain a comfortable indoor temperature regardless of the outside weather conditions. This is because different seasons require different temperature control measures, and the system should be able to adapt accordingly. By designing the system around both heating and cooling requirements, it ensures that the system is versatile and can effectively regulate the indoor temperature in any weather condition.Rate this question:
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- 23.
Package or self-contained all-weather units are not normally made for electric air conditioning and _________.
- A.
Natural gas heat
- B.
Electric heat
- C.
LP gas heat
- D.
Oil heat
Correct Answer
D. Oil heatExplanation
Package or self-contained all-weather units are not normally made for electric air conditioning because they are typically designed to work in conjunction with a heating system. In this case, the correct answer is oil heat, as these units are typically designed to be used with oil heating systems rather than electric heating systems.Rate this question:
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- 24.
The heat anticipator in a thermostat is often a(n) _________ type resistor.
- A.
Ceramic block
- B.
Carbon block
- C.
Adjustable thermistor
- D.
Adjustable wire wound
Correct Answer
D. Adjustable wire woundExplanation
The heat anticipator in a thermostat is often an adjustable wire wound resistor because it allows for precise control of the heat output. This type of resistor can be adjusted to vary the resistance, which in turn affects the amount of heat produced. By adjusting the wire wound resistor, the thermostat can anticipate and regulate the temperature more accurately, ensuring optimal comfort and energy efficiency.Rate this question:
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- 25.
The cooling anticipator in a thermostat is a(n) _________ type resistor.
- A.
Combination
- B.
Fixed
- C.
Adjustable thermistor
- D.
Adjustable wire wound
Correct Answer
B. FixedExplanation
The cooling anticipator in a thermostat is a fixed type resistor. This means that it has a predetermined resistance value that does not change. The fixed resistor is used to regulate the amount of current flowing through the cooling circuit, which helps control the cooling system in the thermostat. By using a fixed resistor, the cooling anticipator can provide a consistent and reliable level of resistance, ensuring accurate temperature control.Rate this question:
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- 26.
When adding a control transformer for an air-conditioning system to an existing heating system, the second transformer can be wired in parallel with the original or _________.
- A.
In series with the original transformer
- B.
As a separate circuit
- C.
In parallel with the fan relay
- D.
In parallel with the compressor contactor
Correct Answer
B. As a separate circuitExplanation
When adding a control transformer for an air-conditioning system to an existing heating system, the second transformer can be wired as a separate circuit. This means that the second transformer is connected independently of the original transformer, allowing it to provide power to the air-conditioning system without interfering with the heating system. Wiring it in parallel with the original transformer or any other component would result in shared power supply and potential conflicts or malfunctions between the two systems.Rate this question:
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- 27.
If reservoir-type humidifiers are not properly maintained, which of the following can be discharged into the air?
- A.
Fungi
- B.
Bacteria
- C.
Algae
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
Reservoir-type humidifiers, if not properly maintained, can lead to the growth and accumulation of fungi, bacteria, and algae in the water. When the humidifier releases mist or steam into the air, these microorganisms can also be discharged along with it. Therefore, all of the above options (fungi, bacteria, and algae) can be discharged into the air if reservoir-type humidifiers are not maintained correctly.Rate this question:
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- 28.
What is the recommended maximum number of grains per pound of material in the water supplied to an atomizing humidifier?
- A.
10
- B.
50
- C.
100
- D.
125
Correct Answer
A. 10Explanation
The recommended maximum number of grains per pound of material in the water supplied to an atomizing humidifier is 10. This means that the water should not contain more than 10 grains of material per pound. Having a higher number of grains can lead to clogging and damage to the humidifier, so it is important to ensure the water is within this recommended limit.Rate this question:
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- 29.
What are the relative humidity limits recommended for residences?
- A.
20% to 40%
- B.
30% to 50%
- C.
40% to 60%
- D.
50% to 70%
Correct Answer
C. 40% to 60%Explanation
The recommended relative humidity limits for residences are 40% to 60%. This range ensures a comfortable indoor environment and helps to prevent issues such as mold growth, dust mite infestation, and respiratory problems. Humidity levels below 40% can cause dryness and irritation of the skin, eyes, and respiratory system, while levels above 60% can promote the growth of mold and other allergens. Therefore, maintaining a relative humidity between 40% and 60% is ideal for a healthy and comfortable living space.Rate this question:
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- 30.
A high density fiberglass filter media air filter will catch and retain _________% of the particles in the air.
- A.
70
- B.
80
- C.
90
- D.
95
Correct Answer
A. 70Explanation
A high density fiberglass filter media air filter is effective in catching and retaining 70% of the particles in the air. This type of filter has a dense structure that enables it to trap a significant amount of airborne particles, such as dust, pollen, and other contaminants. While it may not capture as many particles as filters with higher percentages, it still provides a good level of filtration and can help improve indoor air quality.Rate this question:
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- 31.
If air conditioning is to be added to an existing forced-air heating system, what must be taken into account?
- A.
Duct size
- B.
Fan speed
- C.
Required air volume
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
When adding air conditioning to an existing forced-air heating system, all of the mentioned factors must be taken into account. The duct size needs to be appropriate to ensure efficient airflow and distribution of cooled air. The fan speed may need to be adjusted to accommodate the additional cooling load. Lastly, the required air volume must be calculated to ensure that the system can effectively cool the space. Considering all these factors is crucial to ensure the successful integration of air conditioning into the existing heating system.Rate this question:
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- 32.
A three ton air conditioning unit will require approximately _________ of air flow.
- A.
400 CFM/ton
- B.
1,200 CFM
- C.
1,200 CFM/ton
- D.
Both a and b
Correct Answer
D. Both a and bExplanation
A three ton air conditioning unit will require approximately 400 CFM/ton of air flow. This means that for a three ton unit, the total air flow required would be 3 tons multiplied by 400 CFM/ton, which equals 1,200 CFM. Therefore, both options a and b are correct as they provide the same information about the required air flow for a three ton air conditioning unit.Rate this question:
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- 33.
What can be done to prevent ductwork from sweating?
- A.
Lower the thermostat setting.
- B.
Add dampers.
- C.
Insulate the duct.
- D.
Both a and c are correct.
Correct Answer
C. Insulate the duct.Explanation
Insulating the duct can prevent ductwork from sweating because it helps to maintain a consistent temperature inside the duct, preventing condensation from forming on the surface. This insulation acts as a barrier, preventing the warm air inside the duct from coming into contact with the cold surface of the duct, thus reducing the likelihood of sweating.Rate this question:
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- 34.
Typically, an air-conditioning (cooling) system requires an airflow through the evaporator of _________ cfm per 12,000 Btu/h capacity.
- A.
340
- B.
360
- C.
400
- D.
420
Correct Answer
C. 400Explanation
An air-conditioning system requires a specific airflow through the evaporator to effectively cool the space. The airflow is measured in cubic feet per minute (cfm) and is dependent on the cooling capacity of the system. In this case, the correct answer of 400 cfm per 12,000 Btu/h capacity means that for every 12,000 British thermal units per hour, the system needs an airflow of 400 cubic feet per minute to operate efficiently.Rate this question:
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- 35.
If a technician connects gauges on the line set of the outdoor unit of a heat pump operating in the heating mode, _________.
- A.
The high pressure gauge will read the high side pressure and the low pressure gauge will most likely be the RETARD range
- B.
The high pressure gauge will read the high side pressure and the low pressure gauge will read the suction pressure
- C.
Both gauges will read the suction pressure
- D.
The high pressure gauge will read the suction pressure and the low pressure will read discharge pressure
Correct Answer
A. The high pressure gauge will read the high side pressure and the low pressure gauge will most likely be the RETARD rangeExplanation
When a technician connects gauges on the line set of the outdoor unit of a heat pump operating in the heating mode, the high pressure gauge will read the high side pressure. This is because the high side of the heat pump is where the refrigerant is compressed and has a higher pressure. On the other hand, the low pressure gauge will most likely be in the RETARD range. This is because the low side of the heat pump is where the refrigerant is expanded and has a lower pressure. The RETARD range on the low pressure gauge is specifically designed to measure lower pressures accurately.Rate this question:
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- 36.
What prevents cold air from being circulated to the heated space during the defrost cycle?
- A.
The auxiliary heater turns on to "temper" the air.
- B.
All of the dampers close automatically.
- C.
The indoor fan motor turns off.
- D.
Both a and b are correct.
Correct Answer
A. The auxiliary heater turns on to "temper" the air.Explanation
During the defrost cycle, the auxiliary heater turns on to "temper" the air, which means it warms up the air before it is circulated into the heated space. This prevents cold air from being circulated, ensuring that the heated space remains warm and comfortable. Additionally, all of the dampers close automatically, further preventing any cold air from entering the heated space. Therefore, both options a and b are correct.Rate this question:
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- 37.
An air-to-air heat pump would least likely be seen in _________.
- A.
Florida
- B.
Maine
- C.
Hawaii
- D.
Mexico
Correct Answer
B. MaineExplanation
An air-to-air heat pump works by transferring heat from the outside air to the inside of a building. Maine has a cold climate for most of the year, with long winters and low temperatures. Therefore, it is less likely to find an air-to-air heat pump in Maine as the cold temperatures may limit the efficiency and effectiveness of the heat pump in extracting heat from the outside air.Rate this question:
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- 38.
The main valve in a 4-way reversing valve is moved by pressure created by _________.
- A.
Refrigerant boiling in the coil
- B.
Pressure reduction in the condenser
- C.
Change in the action of the metering device
- D.
Low and high side pressure difference
Correct Answer
D. Low and high side pressure differenceExplanation
The main valve in a 4-way reversing valve is moved by the pressure difference between the low side and high side of the system. This pressure difference is created when the compressor compresses the refrigerant, causing it to become high pressure on the high side and low pressure on the low side. The pressure difference is what allows the valve to switch the flow of refrigerant, reversing the direction of the system and enabling functions such as heating and cooling.Rate this question:
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- 39.
Termination of the defrost cycle occurs when the liquid of the outside coil reaches _________.
- A.
35° F
- B.
45° F
- C.
50° F
- D.
65° F
Correct Answer
C. 50° FExplanation
The termination of the defrost cycle occurs when the liquid of the outside coil reaches 50° F. This temperature is significant because it indicates that the coil is no longer frozen and can resume normal operation. At this point, the defrost cycle is no longer necessary as the coil has reached a temperature that allows for efficient heat exchange.Rate this question:
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- 40.
The suction line is connected between the _________.
- A.
Inside and outside coil outlets
- B.
Inside and outside metering devices
- C.
Compressor and the defrost relay
- D.
Compressor, accumulator, and reversing valve
Correct Answer
D. Compressor, accumulator, and reversing valveExplanation
The suction line is a refrigerant line that connects the compressor, accumulator, and reversing valve. The compressor is responsible for compressing the refrigerant gas, the accumulator stores excess refrigerant and removes any liquid refrigerant, and the reversing valve controls the direction of refrigerant flow in the system. Therefore, the suction line connects these three components to allow the refrigerant to flow between them.Rate this question:
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- 41.
The hot gas line is always connected between the _________.
- A.
Compressor and the condenser
- B.
Reversing valve and the condenser
- C.
Reversing valve and the accumulator
- D.
Compressor and the reversing valve
Correct Answer
D. Compressor and the reversing valveExplanation
The hot gas line is always connected between the compressor and the reversing valve. This is because the hot gas line carries the high-pressure, high-temperature refrigerant gas from the compressor to the reversing valve. The reversing valve is responsible for changing the direction of the refrigerant flow, allowing the system to switch between heating and cooling modes. Therefore, the hot gas line needs to be connected between these two components to ensure proper operation of the HVAC system.Rate this question:
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- 42.
A pressure-temperature defrost control is activated by the _________.
- A.
Difference of the pressure in the fan compartment and the temperature of the coil
- B.
Difference in pressure between the outdoor pressure and the fan discharge pressure
- C.
Difference in the pressure of air through the outdoor coil
- D.
Difference in pressure of the refrigerant in the condenser and the pressure in the coil
Correct Answer
C. Difference in the pressure of air through the outdoor coilExplanation
The correct answer is "difference in the pressure of air through the outdoor coil." A pressure-temperature defrost control is activated by monitoring the pressure difference of the air flowing through the outdoor coil. When the pressure difference reaches a certain threshold, it indicates that the coil is becoming blocked or restricted, which can impede the heat transfer process. The defrost control then initiates a defrost cycle to melt any ice or frost buildup on the coil and restore proper airflow and heat transfer efficiency.Rate this question:
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- 43.
When the water and refrigerant in a heat exchanger flow in opposite directions, it is referred to as _________.
- A.
Countersink
- B.
Parallel flow
- C.
Counter flow
- D.
Bias flow
Correct Answer
C. Counter flowExplanation
When the water and refrigerant in a heat exchanger flow in opposite directions, it is referred to as counter flow. In this configuration, the hot and cold fluids enter the heat exchanger at opposite ends and flow in opposite directions, allowing for efficient heat transfer between the two fluids. This counter flow arrangement maximizes the temperature difference between the hot and cold fluids, resulting in improved heat transfer efficiency compared to parallel flow.Rate this question:
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- 44.
Many coaxial heat exchanged are made of _________.
- A.
Steel
- B.
Aluminum
- C.
Nickel
- D.
Cupro-nickel
Correct Answer
D. Cupro-nickelExplanation
Coaxial heat exchangers are commonly made of cupro-nickel. Cupro-nickel is a type of alloy that is a combination of copper and nickel. This alloy is known for its excellent corrosion resistance, high thermal conductivity, and durability. These properties make it an ideal material for heat exchangers, as it can efficiently transfer heat between two fluids without corroding or degrading over time. Additionally, cupro-nickel is also resistant to biofouling, making it suitable for applications involving seawater or other corrosive environments.Rate this question:
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- 45.
In a closed-loop system, the plastic water pipes that are buried in the Earth are called _________.
- A.
Ground loops
- B.
Thermal loops
- C.
Water loops
- D.
Both a and c
Correct Answer
D. Both a and cExplanation
In a closed-loop system, the plastic water pipes that are buried in the Earth serve as ground loops, as they extract or deposit heat from or into the ground. These ground loops are also referred to as water loops, as they circulate water to transfer heat. Therefore, the correct answer is both a and c.Rate this question:
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- 46.
The hot gas line from the heat pump's compressor can be used to _________.
- A.
Cool down the condenser
- B.
Heat domestic water
- C.
Keep the well water from freezing
- D.
Both a and c
Correct Answer
B. Heat domestic waterExplanation
The hot gas line from the heat pump's compressor can be used to heat domestic water. This is because the hot gas line carries high-temperature gas from the compressor, which can be used to transfer heat to the water, raising its temperature for domestic use.Rate this question:
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- 47.
An advantage of a "series flow" configuration of ground loops is _________.
- A.
Smaller diameter pipes
- B.
Ease of removing trapped air
- C.
Lower installation costs
- D.
Less antifreeze is required
Correct Answer
B. Ease of removing trapped airExplanation
In a series flow configuration of ground loops, the fluid flows in a linear manner from one loop to another. This allows for easier removal of trapped air within the system. As the fluid moves through each loop, any air bubbles can be easily pushed out, ensuring efficient heat transfer and preventing any potential blockages or inefficiencies. This advantage makes the series flow configuration desirable in geothermal heating and cooling systems.Rate this question:
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- 48.
An advantage of a "parallel flow" configuration of ground loop is _________.
- A.
Smaller diameter pipes
- B.
Ease of removing trapped air
- C.
Simplified flow path
- D.
Higher heat transfer per foot
Correct Answer
A. Smaller diameter pipesExplanation
In a "parallel flow" configuration of a ground loop, the advantage of using smaller diameter pipes is that they allow for more efficient heat transfer. Smaller pipes have a larger surface area to volume ratio, which means that heat can be transferred more effectively between the ground and the fluid circulating in the loop. This can result in higher overall heat transfer per foot of pipe, making the system more efficient and potentially reducing installation costs. Additionally, smaller diameter pipes can be easier to install and require less space, providing additional benefits in terms of ease of installation and system design.Rate this question:
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- 49.
What is the temperature differential between water in and water out of heat exchanger that has transferred 50,000 Btu/h? The flow rate is 10 gallons per minute.
- A.
10°
- B.
20°
- C.
50°
- D.
5°
Correct Answer
A. 10° -
- 50.
Generally speaking, electric heat is very efficient but costs more when compared to oil and gas.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Electric heat is generally more efficient than oil and gas because it converts nearly all the energy it uses into heat. In contrast, oil and gas heating systems may lose some energy through combustion or heat transfer. However, electric heat is typically more expensive to operate because electricity is often priced higher than oil or gas. Therefore, the statement that electric heat is very efficient but costs more when compared to oil and gas is true.Rate this question:
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