What is the advantage of a reducing plenum system?

Reduces duct size to save material and maintain pressure

What issue can occur if too many zone dampers close in a single-speed blower system?

Excessive noise and high velocity

Where is a perimeter loop system most effective?

Installed in a concrete floor in a colder climate

What is the purpose of an air friction chart?

To determine recommended duct sizes and velocities

Why are return grilles typically NOT placed in kitchens or bathrooms?

They can cause odors to spread throughout the system

What is an advantage of an individual return-air system?

Provides the most efficient return airflow

What is the purpose of a supply duct system?

Distribute conditioned air to terminal units, registers, or diffusers

Why should turning vanes be used in duct corners?

To improve airflow around bends

How does a variable-speed blower improve zoning systems?

It allows for efficient heating and cooling in different zones

How is air quantity in a duct measured?

By calculating the area and velocity (cfm = Area × Velocity)

What are "as-built" drawings?

Original drawings revised to reflect field changes

What is the purpose of zoning in an air distribution system?

Maintain different temperatures in different areas

What factor causes friction loss in ductwork?

The smoothness of the duct’s interior surface

How is fan noise reduced in return-air systems?

Installing return-air plenums away from the furnace

What is the purpose of a vibration eliminator in a duct system?

Reduce noise and vibration from the blower

What is the function of a balancing damper?

Controls and balances airflow in the system

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7U 1H

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Questions 20

Answers

1
What is the advantage of a reducing plenum system?
Provides constant airflow regardless of system size
Reduces duct size to save material and maintain pressure
Allows for separate heating and cooling zones
Increases the air temperature before delivery
2
What issue can occur if too many zone dampers close in a single-speed blower system?
Increased humidity levels
Air filters become clogged
Excessive noise and high velocity
Decreased air pressure in the ducts
3
Which of the following is NOT a type of duct system?
Reducing plenum system
Plenum system
Extended plenum system
Heat pump loop system
4
Where is a perimeter loop system most effective?
In a warm climate
Installed in a concrete floor in a colder climate
Used only in rooftop HVAC systems
Inside office buildings with high ceilings
5
What is the purpose of an air friction chart?
To calculate the cooling load of an HVAC system
To determine recommended duct sizes and velocities
To measure the temperature difference in a plenum
To measure humidity levels in ductwork
6
Why are return grilles typically NOT placed in kitchens or bathrooms?
They require special air filters
They reduce overall system efficiency
They create excess air circulation
They can cause odors to spread throughout the system
7
What is an advantage of an individual return-air system?
Provides the most efficient return airflow
Reduces the need for air filters
Requires fewer ducts than a central return system
Increases cooling coil efficiency
8
What is the purpose of a supply duct system?
Act as a sound barrier
Remove air from a building
Distribute conditioned air to terminal units, registers, or diffusers
Provide cooling for electrical systems
9
Why should turning vanes be used in duct corners?
To increase noise reduction
To prevent contaminants from spreading
To slow air down for better heating
To improve airflow around bends
10
How does a variable-speed blower improve zoning systems?
It eliminates the need for a thermostat
It operates continuously at one speed
It reduces the need for ductwork
It allows for efficient heating and cooling in different zones
11
How is air quantity in a duct measured?
By calculating the area and velocity (cfm = Area × Velocity)
Measuring sound levels near the air return
Using a standard thermometer
Measuring sound levels near the air return
12
What are "as-built" drawings?
Manuals for installing HVAC systems
Original drawings revised to reflect field changes
Blueprints of a system before construction
Standard HVAC component layouts
13
What is the purpose of zoning in an air distribution system?
Distribute fresh air to different rooms
Maintain different temperatures in different areas
Reduce humidity levels
Increase airflow for better ventilation
14
What factor causes friction loss in ductwork?
The number of fans in the system
The size of the return-air grilles
The shape of the air filter
The smoothness of the duct’s interior surface
15
How is fan noise reduced in return-air systems?
Using a central return system only
Installing return-air plenums away from the furnace
Removing all dampers from the system
Increasing the system's air velocity
16
What is the purpose of a vibration eliminator in a duct system?
Increase airflow speed
Heat the air in colder climates
Increase duct pressure
Reduce noise and vibration from the blower
17
Which type of duct system extends the plenum closer to the farthest point in a building?
Perimeter loop system
Central return system
Extended plenum system
Reducing plenum system
18
What component connects branch ducts to the main trunk duct?
Air return grille
Turning vane
Air filter
Takeoff fitting
19
Where are supply diffusers typically located in a plenum system?
On the inside walls
Next to exterior walls
Ceiling only
On the floor
20
What is the function of a balancing damper?
Absorbs sound in HVAC systems
Increases temperature in the duct
Prevents contaminants from entering the duct
Controls and balances airflow in the system

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