What Are HVAC Ducts?

When you think of HVAC systems, you might think of the bulky appliances that sit outside your home or in your basement. Sometimes you think about the vents in your living areas, bedroom, or kitchen. But many people are not aware of the metal channels that connect your AC units to those vents.

What are HVAC ducts? Ducts are passages or conduits used in HVAC to deliver and remove air in your space. These airflows include supply air, return air, and some exhaust air. Ducts are known to deliver ventilation air as part of the supply air.

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Read on to find out everything about HVAC ducts and the ductwork system in general such as its function, materials used, and many more.

The Function Of The Duct System

A ductwork system is installed in your house if you want to distribute airflow from your HVAC equipment to your home or living space. It consists of air sucked from the whole establishment into the air conditioner or heater, where it will get cooled or heated. It will then pushed back using ducts into your indoor living space.

The efficiency of the duct system will determine the input and output of air. If you do not have a properly designed duct system, the heating and cooling system, together with the air pressure, will be off. As a result, your climate control and home’s efficiency will suffer.

Materials Used In Ductwork

When it comes to ductwork, there are plenty of materials available for your ducts. It varies depending on your needs in terms of financial capability or what your construction company will recommend.

Galvanized Steel

Galvanized steel is one of the most popular and standard materials used to install and fabricate ductwork. It has zinc coating in the metal that can hinder rust and helps you to avoid painting costs. The metal ducts are usually lined using fiberglass blankets and wrapped with duct wrap externally.


Aluminum will be your choice if you are looking for something light and easy to install. It is very easy to find and get it custom-made, depending on the fabricated shapes. Aluminum ducts are not the popular choice by many compared to galvanized steel.

Polyurethane And Phenolic Panels

These are foam panels that are crafted using a factory-applied aluminum that is finished on both sides. The thickness of the aluminum foil varies depending on whether it will be used indoors or placed outside. Pentane is used to act as a foaming agent instead of CFC, HFC, HCFC, or HC gasses.

Fiberglass Duct Board

It is the kind of panel that is designed for thermal insulation. The interior surface can absorb sound, providing you a quiet operation when it comes to heating and cooling.

Flexible Ducting

These ducts are more flexible plastic over a metallic wire coil so that it can be shaped into a tube. These flexible ducts came in a different range of configurations and are known to be convenient for attaching outlets that supply air to the rigid ductwork system.

Parts Of The Ductwork System

A ductwork system has other components that the ducts itself. It helps the system to operate as expected to deliver high-quality air in your entire home and commercial building. Here are some of the key components of a ductwork system and their functions:

Vibration Isolators

These isolators are flexible sections that are inserted in the duct after or before an air handler. It is to minimize all the vibrations that can occur when a duct system is installed and running.

A duct system starts with an air handler that contains blowers, and these blowers can create substantial vibration. It will make the duct system transmit the vibration and noise throughout the building.

Volume Control Dampers

In terms of the duct system, it needs to have a way to adjust the airflow volume in different sections of the unit. Volume control dampers can help with this function and can be automatic or manual. These automatic controllers are provided by the zone dampers, while the variable air volume controls the complex systems.

Smoke And Fire Dampers

These components can be found in your duct system if the duct passes through a fire curtain or firewall. They are specially designed to seal off a duct immediately once it detects fire or smoke. It will remain sealed until a technician opens them up manually.

Turning Vanes

If you want to reduce all the resistance and turbulence to the flow of the air, you might need to install a turning vanes. They are designed to guide the air and helping it change in different directions easily.


Plenums are the central collection and distribution units in your HVAC system. The return plenums can carry air from many return vents into the centralized air handler. On the other hand, the supply plenum directs all air from the central unit into the rooms that need cooling or heating.

Terminal Units

When dealing with terminal units, these are commonly found in the branch ducts in multi-zone HVAC systems. Each thermal zone has its terminal unit, and some of them are fan-powered mixing boxes. Sometimes terminal units contain a cooling or heating coil.

Air Terminals

Air terminals are the outlets that supply air or exhaust air inlets. When it comes to dealing with the supply of air, diffusers are found in a smaller HVAC system, and they are used in residential types of housing. Exhaust grilles are used for the sake of appearance, though some of them have an air filter.


Overall, it is vital to get a quality air in your home or commercial spaces and having an efficient duct system will do the trick. Proper installation is the key, and you should always consult professional help to do all the installation.

They can evaluate your needs and ensure you get a system that is working efficiently and effectively. You can always choose the materials you prefer but take into consideration what the professional is saying.

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