Ductwork

What Is Ductwork?

Ductwork is the system that distributes heated, cooled, and ventilated air from a commercial HVAC system throughout a building. Often compared to the circulatory system of a building, it is a critical system for ensuring thermal comfort, maintaining indoor air quality, while limiting noise. The design and proper sealing of ductwork are essential for the overall efficiency and performance of the HVAC system.

The primary role of ductwork is to serve as a conduit for conditioned air. This involves two key processes:

• Supply Air: The ductwork carries conditioned air from an HVAC unit and distributes it to one or more zones within the building.
• Return Air: The ductwork carries air from one or more zones or the return air plenum to the HVAC unit. Return air may be exhausted or recirculated. 

A well-designed HVAC ductwork system ensures consistent air distribution, balanced airflow, and helps to minimize energy loss. Inefficient or leaky ductwork can lead to significant energy waste, with some estimates suggesting that up to 30% of conditioned air can be lost. Well-designed ductwork systems are designed to operate quietly and minimize excessive HVAC noise.

Types of Ductwork

Commercial HVAC ductwork is commonly made of different types of material: 

• Galvanized steel: A popular choice due to its durability and resistance to corrosion.
• Aluminum: Lighter than galvanized steel and offers excellent corrosion resistance.
• Flexible ductwork: Often used in tight or unusually shaped spaces to connect to VAV terminal units, it consists of a spring steel wire helix covered with a durable, flexible plastic and insulation.
• Fabric ductwork: often made of polyester and designed to operate under positive pressure. May be removed for cleaning.

Commercial HVAC Systems that Require Ductwork

Many commercial HVAC systems rely on ductwork to deliver conditioned air. These systems are often chosen for their ability to provide consistent and widespread temperature control in larger buildings. Common systems that typically require ductwork include:

• Air handlers: These units are a core component of many commercial HVAC systems and are responsible for circulating conditioned air through the ductwork.
• Dedicated outdoor air units: Systems designed to dehumidify, cool, and heat ventilation air for distribution to occupied zones or terminal units. 
• Rooftop units (RTUs): These are packaged systems that contain all the heating and cooling components in a single unit placed on the roof. They connect directly to the building's ductwork to distribute conditioned air. Trane offers various RTU models, such as the Precedent® and IntelliPak® lines, which are designed for ducted applications.
• Split systems: These systems have both an indoor and an outdoor unit. The indoor unit, often an air handler or furnace, connects to the ductwork to circulate air throughout the building. Standard split systems are a common choice for smaller commercial buildings.
• Terminal systems: Small, zoned terminal units may use a short section of supply and/or return air ductwork for air delivery. Common examples include vertical stack fan coils, vertical stack water-source heat pumps, some sensible cooling chilled water terminal units, and some VRF terminal units.

Resources for Ductwork

• VariTrane Duct Designer
• Get Your Ducts in a Row to Unlock Hidden Energy Savings Potential

If you're planning to upgrade your building's infrastructure and have questions about ductwork, contact your local Trane representative.