Air Conditioning Systems Introduction
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Questions and Answers

What is the function of an air conditioning plant in a summer system?

  • Acts as a heat sink (correct)
  • Transfers energy to the conditioned space
  • Circulates water between the conditioned space and the plant
  • Introduces fresh air into the conditioned space

    • Which media is NOT mentioned as used for transferring energy in an air conditioning system?

  • Water
  • Gasoline (correct)
  • Air
  • Refrigerant

    • What is one of the selection criteria for air conditioning systems?

  • System reliability and flexibility (correct)
  • Color of the A/C plant
  • Type of furniture in the conditioned space
  • Number of windows in the conditioned space

    • What role does the thermal distribution system play in an air conditioning system?

    <p>Maintains Indoor Air Quality (IAQ)</p> Signup and view all the answers

    In what season does the air conditioning plant act as a heat source?

    <p>Winter</p> Signup and view all the answers

    Which type of energy has to be supplied to the conditioned space in winter?

    <p>Both sensible and latent heat</p> Signup and view all the answers

    In a single duct, constant volume, single zone system, what controls the amount of water vapor added in the humidifier?

    <p>Humidistat</p> Signup and view all the answers

    What is the main function of a supply fan in the air conditioning system described?

    <p>Controlling airflow</p> Signup and view all the answers

    Which type of air conditioning system uses air as the media to transport energy from the conditioned space to the A/C plant?

    <p>All air systems</p> Signup and view all the answers

    What differentiates single duct systems from dual duct systems in air conditioning?

    <p>Capability to provide either cooling or heating but not both simultaneously</p> Signup and view all the answers

    How is the volumetric flow rate of supply air maintained in a constant volume air conditioning system?

    <p>By regulating damper position</p> Signup and view all the answers

    What is the purpose of a thermostat in the described air conditioning system?

    <p>Sense temperature in the conditioned space</p> Signup and view all the answers

    What distinguishes dual duct systems from single duct systems in air conditioning?

    <p>Ability to provide both heating and cooling simultaneously</p> Signup and view all the answers

    What percentage of outdoor air flow rate is required for ventilation when the outdoor air is too cold or too warm?

    <p>15%</p> Signup and view all the answers

    What outdoor air temperature range allows for 100 percent outdoor air usage according to the text?

    <p>13oC to 24oC</p> Signup and view all the answers

    What is a disadvantage associated with all air systems with respect to space?

    <p>Reduced available floor space</p> Signup and view all the answers

    In all water systems, what fluid is used in the thermal distribution system?

    <p>Water</p> Signup and view all the answers

    Which type of system can be classified as a 2-pipe or 4-pipe system in all water systems?

    <p>All water systems</p> Signup and view all the answers

    What application requires individual control of multiple zones and is suited for all air systems?

    <p>Office buildings</p> Signup and view all the answers

    What is a potential advantage of all air systems mentioned in the text?

    <p>+/- 0.15oC temperature control</p> Signup and view all the answers

    What is the main advantage of variable air volume (VAV) systems compared to constant volume systems?

    <p>Significantly lower power consumption in perimeter zones</p> Signup and view all the answers

    In dual duct, constant volume systems, why do cold air and hot air ducts need to be sized to handle all the air flow rate?

    <p>To maintain constant airflow rate to each zone</p> Signup and view all the answers

    What issue can arise in VAV systems when zone loads are very low?

    <p>Problems with ventilation, IAQ, and room air distribution</p> Signup and view all the answers

    What is a key advantage of dual duct systems in maintaining indoor air quality (IAQ)?

    <p>The ability to maintain required conditions precisely</p> Signup and view all the answers

    Why do dual duct systems occupy more space compared to other HVAC systems?

    <p>Due to the need for sizing both cold and hot air ducts for all airflow rates</p> Signup and view all the answers

    What is a disadvantage of dual duct, constant volume systems regarding energy efficiency?

    <p>High energy consumption due to simultaneous cooling and heating</p> Signup and view all the answers

    Why is it challenging to control humidity precisely using VAV systems?

    <p>Zone loads may be very low</p> Signup and view all the answers

    What is an advantage of dual duct systems that allows for simultaneous cooling and heating in different zones?

    <p>Responsiveness to variations in zone load</p> Signup and view all the answers

    In dual duct, variable air volume systems, what differentiates them from dual duct, constant volume systems?

    <p>Reduce airflow rate as zone load drops</p> Signup and view all the answers

    Why is outdoor airflow needed in all air systems?

    <p>To control the position of exhaust and outdoor air dampers</p> Signup and view all the answers

    What component controls the flow rate of hot or cold water to the conditioned space in a HVAC system?

    <p>Zone thermostat</p> Signup and view all the answers

    In a 4-pipe system, how many supply pipelines are there for cold and hot water?

    <p>Two (one for cold water and one for hot water)</p> Signup and view all the answers

    Which equipment is used for transferring heat in a HVAC system besides bare pipes?

    <p>Convector</p> Signup and view all the answers

    What is the main purpose of the drain tray in a fan coil unit?

    <p>To prevent dust accumulation on cooling coil</p> Signup and view all the answers

    How is heat transferred between a convector and the surrounding air?

    <p>By convection only</p> Signup and view all the answers

    What controls the capacity of a fan coil unit in an HVAC system?

    <p>Cold water flow rate or air flow rate</p> Signup and view all the answers

    In a 2-pipe system used with 4-pipe systems, what is used as a heating coil in a fan coil unit?

    <p>Electric heater</p> Signup and view all the answers

    What differentiates a unit ventilator from a regular fan coil unit?

    <p>Provision for introducing treated ventilation air to the conditioned space</p> Signup and view all the answers

    How does a radiator primarily transfer heat to the surrounding air?

    <p>By radiation only</p> Signup and view all the answers

    What plays the key role in providing required conditions inside the conditioned space in a HVAC system?

    <p>The cold and dehumidified air supplied to the conditioned space</p> Signup and view all the answers

    What is the main advantage of face-and-bypass control over coil control in a single zone system?

    <p>Precise control over zone humidity</p> Signup and view all the answers

    When transitioning from the cooling season to the heating season in a single zone system using coil control, what happens to the cooling coil valve?

    <p>It is gradually closed</p> Signup and view all the answers

    Why is controlling zone humidity more challenging in coil control compared to face-and-bypass control?

    <p>Dehumidification rate decreases with cold water flow rate</p> Signup and view all the answers

    What is one of the disadvantages of single duct, multiple zone systems with reheat coils?

    <p>High energy consumption for cooling</p> Signup and view all the answers

    Why is it not economically feasible to provide separate single zone systems for each zone in very large buildings?

    <p>High initial installation cost</p> Signup and view all the answers

    In a single duct, constant volume, multiple zone system with reheat coils, what controls the amount of reheat and therefore the supply air temperature in each zone?

    <p>Thermostat in each zone</p> Signup and view all the answers

    What is one disadvantage of face-and-bypass control in a single zone system?

    <p>High cost</p> Signup and view all the answers

    What is a disadvantage of air-water systems according to the text?

    <p>Complex operation and control due to handling both primary air and secondary water</p> Signup and view all the answers

    Why might secondary water coils in air-water systems become dirty?

    <p>Lack of good quality filters in the room units</p> Signup and view all the answers

    What is a key advantage of unitary refrigerant-based systems mentioned in the text?

    <p>Factory assembled and tested as per standard specifications</p> Signup and view all the answers

    Where are split type room air conditioners typically installed?

    <p>Outside, with only the indoor unit inside</p> Signup and view all the answers

    Which factor might lead to condensation on the cooling coil of secondary water in air-water systems?

    <p>A low latent load on the building</p> Signup and view all the answers

    What is a disadvantage of shutting down primary air supply to unoccupied spaces in air-water systems?

    <p>It is not possible due to limitations in room control mechanisms</p> Signup and view all the answers

    Why are fan coil units mentioned in the text?

    <p>$0.3 TR$ to $3.0 TR$ cooling capacities</p> Signup and view all the answers

    What is a characteristic feature of a split type room air conditioner according to the text?

    <p>$0.3 TR$ minimum cooling capacity</p> Signup and view all the answers

    What is a drawback mentioned for all water systems compared to air-water systems?

    <p>Increased space requirement compared to air-water systems</p> Signup and view all the answers

    Which advantage of air-water systems contributes to avoiding problems related to odors or fungal growth in conditioned spaces?

    <p>Absence of latent heat transfer requirement in cooling coils</p> Signup and view all the answers

    What is a benefit of all water systems in buildings requiring individual room control?

    <p>No need for separate ventilation systems</p> Signup and view all the answers

    What is a disadvantage of all water systems compared to all air systems regarding maintenance?

    <p>Higher maintenance requirements</p> Signup and view all the answers

    In air-water systems, what is the function of the primary air?

    <p>Supplying ventilation and latent load offset</p> Signup and view all the answers

    What type of control valve is mentioned as difficult to use for humidity control during summer?

    <p>Chilled water control valves</p> Signup and view all the answers

    What is a potential health issue associated with draining condensate water in all water systems?

    <p>Higher risk of mold growth</p> Signup and view all the answers

    Which type of system allows for the use of solar or waste heat for winter heating?

    <p>All water systems</p> Signup and view all the answers

    What is a distinguishing feature of an induction unit in an air-water system?

    <p>&quot;Induced flow of secondary air&quot;</p> Signup and view all the answers

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