Podcast
Questions and Answers
What is a primary advantage of a dual-duct system?
What is a primary advantage of a dual-duct system?
- It eliminates the need for separate supply ducts.
- It uses only one duct for both heating and cooling.
- It requires less initial investment compared to other systems.
- It can effectively serve highly variable sensible-heat loads. (correct)
What is a key limitation of using a dual-duct air system?
What is a key limitation of using a dual-duct air system?
- It needs additional space for two supply ducts. (correct)
- It can only be used in smaller buildings.
- It has a low operational cost.
- It does not require any maintenance.
How do fan coil units (FCUs) primarily operate?
How do fan coil units (FCUs) primarily operate?
- By circulating large volumes of air throughout the building.
- By driving air past heating or cooling coils with a fan. (correct)
- By utilizing ductwork exclusively for air distribution.
- By using a centralized air distribution system.
What type of maintenance do fan coil units typically require?
What type of maintenance do fan coil units typically require?
What type of systems uses hot or chilled water to transfer heat?
What type of systems uses hot or chilled water to transfer heat?
What is a primary function of air-handling units (AHUs)?
What is a primary function of air-handling units (AHUs)?
Which of the following is a major disadvantage of all-air systems?
Which of the following is a major disadvantage of all-air systems?
In what type of buildings are all-air systems generally recommended?
In what type of buildings are all-air systems generally recommended?
Which component is not typically part of an air-handling unit?
Which component is not typically part of an air-handling unit?
What does an air-water system utilize for temperature control?
What does an air-water system utilize for temperature control?
Which of the following best describes the role of filters in an air-handling unit?
Which of the following best describes the role of filters in an air-handling unit?
What is the primary purpose of the relief air damper in an AHU?
What is the primary purpose of the relief air damper in an AHU?
What happens to the dampers when the system is turned off?
What happens to the dampers when the system is turned off?
Which component is crucial for controlling the mixed air temperature in a ventilation system?
Which component is crucial for controlling the mixed air temperature in a ventilation system?
If the outside temperature is below 13°C, how is the required mixed temperature of 13°C achieved?
If the outside temperature is below 13°C, how is the required mixed temperature of 13°C achieved?
What is the most controllable type of heating coil mentioned?
What is the most controllable type of heating coil mentioned?
What is a potential drawback of using an electric coil for heating?
What is a potential drawback of using an electric coil for heating?
What can cause condensation on a cooling coil?
What can cause condensation on a cooling coil?
How does the position of the dampers adjust when maintaining a set mixed temperature?
How does the position of the dampers adjust when maintaining a set mixed temperature?
What problem does a gas-fired heater potentially have compared to other heating options?
What problem does a gas-fired heater potentially have compared to other heating options?
What is typically installed downstream of the filter in a ventilation system?
What is typically installed downstream of the filter in a ventilation system?
What is the typical range for cooling water temperature used in a cooling coil?
What is the typical range for cooling water temperature used in a cooling coil?
What primarily controls the operation of a humidifier?
What primarily controls the operation of a humidifier?
What is the primary purpose of the fan in an air treatment system?
What is the primary purpose of the fan in an air treatment system?
In a single-zone system, what factor directly influences the heating or cooling effect of the treated airflow?
In a single-zone system, what factor directly influences the heating or cooling effect of the treated airflow?
What do individual thermostats in a multiple zone air system control?
What do individual thermostats in a multiple zone air system control?
What is a key advantage of Single-Duct, Variable-Air-Volume Systems (VAV)?
What is a key advantage of Single-Duct, Variable-Air-Volume Systems (VAV)?
What limitation is associated with Single-Duct, Variable-Air-Volume Systems (VAV)?
What limitation is associated with Single-Duct, Variable-Air-Volume Systems (VAV)?
What is the function of the reheat coil in a Single-Duct, Zoned-Reheat, Constant-Volume System?
What is the function of the reheat coil in a Single-Duct, Zoned-Reheat, Constant-Volume System?
What mechanism is used in VAV systems to control the airflow rate into a zone?
What mechanism is used in VAV systems to control the airflow rate into a zone?
Which statement accurately describes the capabilities of single-zone systems?
Which statement accurately describes the capabilities of single-zone systems?
What is one common characteristic of all air treatment systems discussed?
What is one common characteristic of all air treatment systems discussed?
What is the main purpose of the inlet louver in a single zone air distribution system?
What is the main purpose of the inlet louver in a single zone air distribution system?
In Building C, how is heating supplied to the air distribution system?
In Building C, how is heating supplied to the air distribution system?
What mechanism is used in the mixing section of a single zone system?
What mechanism is used in the mixing section of a single zone system?
Which building utilizes both electrical supply and gas supply for its single zone system?
Which building utilizes both electrical supply and gas supply for its single zone system?
What is a potential function of the return air damper in a single zone system?
What is a potential function of the return air damper in a single zone system?
What type of supply is required for cooling in Building D's air distribution system?
What type of supply is required for cooling in Building D's air distribution system?
How does Building A acquire its energy supply for heating and cooling?
How does Building A acquire its energy supply for heating and cooling?
What kind of air system design does the content focus on?
What kind of air system design does the content focus on?
What is the purpose of the control valve in the heating or cooling coils?
What is the purpose of the control valve in the heating or cooling coils?
Flashcards
Air Distribution Systems
Air Distribution Systems
Air distribution systems are designed to deliver conditioned air throughout a building, using a network of air handling units (AHU) and ductwork.
All-air Systems
All-air Systems
All-air systems use AHUs to condition air centrally and distribute it via ductwork.
Air-Water Systems
Air-Water Systems
Air-water systems combine air-based and water-based cooling to condition spaces.
All-water Systems
All-water Systems
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Air Handling Units (AHUs)
Air Handling Units (AHUs)
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What are the components of an AHU?
What are the components of an AHU?
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When are all-air systems recommended?
When are all-air systems recommended?
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Single Zone System
Single Zone System
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Supply Air
Supply Air
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Return Air
Return Air
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Energy Supply in Single Zone Systems
Energy Supply in Single Zone Systems
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Air Inlet Louver and Screen
Air Inlet Louver and Screen
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Return Air Damper
Return Air Damper
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Mixing Section
Mixing Section
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Exhaust Air Damper
Exhaust Air Damper
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Parallel Blade Damper
Parallel Blade Damper
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What is a humidifier?
What is a humidifier?
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What is a humidistat?
What is a humidistat?
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What is a fan's role in an HVAC system?
What is a fan's role in an HVAC system?
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What is a single-zone system?
What is a single-zone system?
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What two factors determine the heating/cooling effect of treated air?
What two factors determine the heating/cooling effect of treated air?
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What is a multiple-zone system?
What is a multiple-zone system?
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Describe a Single-Duct, Zoned-Reheat, Constant-Volume System.
Describe a Single-Duct, Zoned-Reheat, Constant-Volume System.
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What is a Single-Duct, Variable-Air-Volume (VAV) System?
What is a Single-Duct, Variable-Air-Volume (VAV) System?
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What are the main advantages of VAV Systems?
What are the main advantages of VAV Systems?
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What are the main limitations of VAV Systems?
What are the main limitations of VAV Systems?
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Mixing Air Streams in Cold Climates
Mixing Air Streams in Cold Climates
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Actuator Function in Air Handling
Actuator Function in Air Handling
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Mixed Temperature Sensor
Mixed Temperature Sensor
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Mixed Temperature Sensor Location
Mixed Temperature Sensor Location
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Setting Mixed Air Temperature
Setting Mixed Air Temperature
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Mixing Air Proportions in Cold Conditions
Mixing Air Proportions in Cold Conditions
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Heating Coil Function
Heating Coil Function
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Electric Heating Coil
Electric Heating Coil
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Gas-Fired Heating Coil
Gas-Fired Heating Coil
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Hot Water Heating Coil
Hot Water Heating Coil
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Constant-Volume Dual-Duct All-Air System
Constant-Volume Dual-Duct All-Air System
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What is the primary advantage of a dual-duct system?
What is the primary advantage of a dual-duct system?
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What does 'constant-volume' refer to in a dual-duct system?
What does 'constant-volume' refer to in a dual-duct system?
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Where is the mixing of air streams done in a dual-duct system?
Where is the mixing of air streams done in a dual-duct system?
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What are the main limitations of a dual-duct system?
What are the main limitations of a dual-duct system?
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Study Notes
Applied Building Services - Lecture 2: Air Distribution Systems
- Air distribution systems are categorized into three main types: all-air, air-water, and all-water systems.
- All-air systems centrally produce conditioned air at an air handling unit (AHU) and distribute it through ductwork to spaces throughout the building.
- Air-water systems combine air-based and water-based cooling methods.
- All-water systems use hot or chilled water to transfer heat to or from a conditioned space through piping connected to a boiler, water heater, or chiller.
Air Handling Units (AHUs)
- Central heating and cooling systems use AHUs to distribute conditioned air.
- AHU functions include drawing outside and return air, mixing them, conditioning the mixed air, blowing the conditioned air into the space, and exhausting excess air.
- AHU components include inlet louver screen, parallel blade dampers, opposed blade dampers, relief air damper, actuator, mixed temperature sensor, heating coil, cooling coil, humidifier, supply fan, return fan, and filters.
Air Handling Unit (AHU) Diagram
- The diagram illustrates the internal components as filter, preheat, cool, heat, and humidify section with air inlet and blow out/fine filter.
Single Zone Systems
- The goal is to supply treated air at a specific temperature.
- The heating or cooling effect depends on the temperature difference between supply and zone air and the flow rate.
- Controllable by changing air volume flow rate, supply air temperature or both.
- Systems have an inlet louver and screen to restrict rain, a return air damper, a relief air damper, a filter, a mixed temperature sensor, heating coil, cooling coil, humidifier, supply fan and return fan.
Mixed Temperature Sensor
- Used for temperature control in single zone systems.
- Normally installed downstream of the filter.
- Start-up: Mixed air temperature equals return air temperature.
- Operation: Outside air is brought into the system upstream of the sensor when dampers are open.
- Common setting: Mixed air temperature is between 13°C and 16°C.
- Adjusting dampers controls the mixed air temperature.
Heating Coil
- Raises the mixed air temperature when needed.
- Can be electric, gas, water or steam.
- Electric coils are common but costly.
- Gas and hot water choices have better cost efficiency but control can be an issue.
Cooling Coil
- Achieves cooling using cold water (5.5–9°C) or refrigerant.
- Condensation may occur due to the lower temperature of the coil.
Humidifier
- Adds moisture to the air by injecting water or steam.
- Controlled by a humidistat.
System Control
- Package rooftop, single-zone units produce treated air at a specific temperature.
- heating or cooling influence depends on the difference between supply and zone temperatures.
- Controlled by altering air volume, supply temperature, or both.
Multiple Zones Air System
- Units serve multiple zones with different varying loads.
- Each zone has an individual thermostat to regulate air volume and/or temperature.
Multiple Zones Air System - Single-Duct, Zoned-Reheat, Constant-Volume systems (Diagram)
- Permit zone control by reheating cool air to the needed temperature within each zone.
- The reheat coil is located near each zone and controlled by its own thermostat. (Diagram shows this system).
Multiple Zones Air System - Single-Duct, Variable-Air-Volume (VAV) Systems
- Used mainly for cooling in hot/warm climates.
- Each zone adjusts its supply air quantity through variable dampers controlled by room thermostats, and the supply fan provides the air.
VAV Advantages and Limitations
- VAV Advantages: Lower initial costs, low operating costs
- VAV Limitations: Poor air circulation at lower flows, leading to insufficient fresh air supply
Multiple Zones Air System- Constant-Volume, Dual-Duct, All-Air Systems
- Uses separate ducts for hot and cold air, and combines them through each zone as needed for temperature control, and maintains constant air flow.
Constant-Volume, Dual-Duct, All-Air Systems (multiple zones)
- Advantages: Serves highly variable loads like hospitals or laboratories
- No reheat coils near zones, avoids hot water coil leakage issue
- Disadvantages: High initial cost, requires two supply ducts, needs extra space above the ceiling
All-Water systems
- Hot or chilled water is used to transfer heat to or from a conditioned space.
- Water flows through pipes connected to a boiler, water heater, or chiller with suitable terminal units in each space.
Fan Coil Units (FCUs)
- Terminal units that condition air.
- Air passes a finned tube containing hot or cold fluid.
- Components include heating/cooling coils, circulation fan, and a control system.
- Typically connected to central boilers or water chillers for heating and cooling respectively.
Fan Coil Unit (FCU) Configurations
- Available in various configurations (e.g., horizontal, vertical).
- Can be used as ductless systems, but also connectable to ductwork.
Air-Water Systems
- Combines air-based and water-based cooling.
- Applicable if the air system doesn't have enough cooling capacity.
- Used for building ventilation, pressurization and where FCU's are used in the water system design.
Air-Water Advantages and Disadvantages
- Advantages: Well-suited for retrofitting existing buildings with space restrictions, good with high sensible loads, works effectively with humidification.
- Disadvantages: Between-season operation may be difficult, mostly useable in exterior zones.
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Description
Test your knowledge on various HVAC systems with this quiz. Questions cover dual-duct systems, fan coil units, air-handling units, and more. Perfect for students and professionals seeking to deepen their understanding of air management systems.
