Air ducts are crucial for regulating both air temperature and air quality in residential and commercial spaces.
To ensure optimal HVAC system performance, it’s important to understand the various types of air ducts, including their materials, designs, and specific uses.
In this guide, we’ll explore the different types of air ducts to help you assess your ventilation needs.
Materials
1. Sheet Metal Air Ducts
Sheet metal ducts are well-known for their strength and long-lasting performance, typically made from galvanized steel or aluminum.
They are highly resistant to damage, offer smooth surfaces for optimal airflow, and are commonly used in commercial and industrial settings.
2. Fiberglass Air Ducts
Fiberglass ducts are lightweight and recognized for their excellent insulation properties. Made from sealed fiberglass board panels, these ducts are commonly used in both residential and commercial spaces to prevent heat loss or gain.
3. Flexible Air Ducts
Flexible ducts consist of a steel spring coil encased in durable plastic, with thermal insulation made from glass wool.
These ducts are perfect for navigating tight corners or unusual spaces, as they are easy to maneuver around obstacles. However, proper installation is essential to avoid restricting airflow.
4. Fiberboard Air Ducts
Fiberboard air ducts are made from compressed resin boards, with an insulating layer on the outer surface. These ducts are cost-effective and can be installed in smaller spaces.
Their smooth surface can trap dust, improving long-term air quality. However, their durability depends on factors like usage and location.
While affordable, these ducts face ventilation challenges, have a shorter lifespan, and are not suitable for outdoor or damp environments.
Designs
1. Rectangular Ducts
Rectangular ducts offer a traditional and budget-friendly solution for various HVAC systems. Their design is particularly popular in commercial buildings due to its ease of manufacturing and installation.
These ducts are ideal for spaces with limited room, as their design allows for better airflow. This increased airflow is especially beneficial in HVAC systems with low pressure.
2. Round Ducts
Round ducts are among the most common types used, especially in residential spaces. Their design allows for smooth airflow due to the ample space inside. A key advantage of round ducts is their easy and quick installation, as joining the pieces is straightforward.
Advantages:
Cost-effective installation.
Enhanced airflow due to the round shape.
Reduced noise during system operation.
Disadvantages:
Height limitations depending on installation location.
3. Oval Ducts
Oval ducts combine elements of both round and rectangular designs. Under higher pressure, their shape becomes more rounded. Some key benefits of oval ducts include:
High airflow efficiency, similar to round ducts.
Reduced air resistance thanks to their smooth, curved surface.
Minimized turbulence noise due to the curved design.
Improved overall performance and reduced air leakage, thanks to their seamless connections.
Purpose
1. Return Ducts
Maintaining balanced airflow in an HVAC system is essential. Return ducts play a key role in bringing air back into the system. Typically located in central areas of homes or near vents, these ducts help remove stale and unconditioned air from the indoor environment.
Once air is drawn into the return ducts, it passes through a filter that removes dust and pollutants. This process ensures that the indoor air quality remains clean and fresh.
2. Supply Ducts
Supply ducts are responsible for delivering conditioned air back into the living spaces. Once the air is conditioned, it flows into the supply ducts, bypassing the home's central ductwork and extending into specific rooms.
Each room is equipped with vents connected to the supply ducts, which can be located on the walls, ceiling, or floor. These individual vents allow for temperature control in each room, ensuring personalized comfort.
As the conditioned air mixes with the existing room air, it creates a comfortable environment. Once the air has done its job, it returns to the system through the return ducts, and the cycle repeats to maintain a consistent temperature.​​
Which Type of Air Duct is Best
Fiberglass and fiberboard ducts are commonly used in commercial buildings because they help reduce noise in large HVAC systems. In contrast, most residential properties use sheet metal ducts, with flexible ducts often installed in tight corners and narrow spaces.
Sheet metal ducts are an excellent choice for residential systems due to their smooth surface, which requires less frequent cleaning. The choice of air duct installation largely depends on the type of building and the available space for installation.
For more guidance on selecting the right air ducts for your property, check out our article, "Choose From Multiple Types of Ductwork For Your Property." It’s always best to consult with trusted HVAC experts to determine which duct system best suits your needs.
Conclusion
Air ducts play a vital role in regulating air quality and temperature in both residential and commercial spaces. Materials such as sheet metal, fiberglass, fiberboard, and flexible ducts each offer distinct advantages.
Different shapes, including oval, rectangular, and circular ducts, are designed to meet specific requirements. The selection of the right air duct primarily depends on the space where it will be installed.
