How Do Air Ducts Work

Air ducts are conduits used in heating, ventilation, and air conditioning (HVAC) systems to deliver or remove heated or cooled air to different rooms and return the same amount of air back to the HVAC system. Air ducts are a major component of your HVAC system. This article will offer you with everything you need to know about air ducts – their main parts, how they work, and how to go about replacing them.

Materials that Can Make Up an Air Duct

Galvanized Steel

This is one of the most used materials for fabricating air ducts because it has a zinc coating that helps prevent rusting and expensive painting costs. For insulation purposes, the air ducts are either lined or wrapped with fiberglass blankets.


Aluminum offers a great air duct material because it is lightweight and thus, easy to install.

Fiberglass Ducts

These are sheet metal ducts with both internal and external linings. They are often used in commercial settings because they help dampen the sound of the HVAC unit.

Flexible Ducting

Flexible ducts are tube-shaped and are usually made of a wire coil, covered with a bendable plastic and surrounded by insulation. This kind of ductwork is ideal for areas where rigid air ducts are hard to install.

Components of an Air Duct System

Vibration Isolators

Blowers in your HVAC system can cause significant vibration, which could spread to different parts of a building. The best way to avoid this is to use vibration isolators that are inserted into an air duct immediately before and after the air handler, which is where the duct system begins.

Take Offs

When a HVAC system has a main air duct that branches into subsidiary branch ducts, fittings referred to as take-offs have to be installed to allow an almost equal amount of air in the main duct to be diverted into the different branch ducts.

Volume Control Dampers

Ducting systems ought to have a way of adjusting airflow volume through the different parts of the HVAC system. Volume control dampers provide this function.

Stack Boots

Air ducts in homes should allow air to travel vertically within thin walls. Such vertical air ducts are referred to as stacks and are formed with either oval sections or wide and thin rectangular sections. At the bottom of the stack, we have a stack boot, which offers transition from a rectangular or round duct to the air duct mounted on the wall.

How an Air Duct System Actually Works

As earlier stated, air ducts are tubes connecting a HVAC system with different air vents installed in a house. The HVAC system pulls in air from the surrounding and cools or heats it, depending on how it is set. They system forces the heated or cooled air through the air ducts and then through the air vents in order to heat or cool the house.
Some people compare air ducts to arteries in the human body – as long as the arteries function well and are clean, the body is able to get the nourishment it needs, enabling all organs to function correctly. On the other hand, if the arteries do not perform their required function, all kinds of problems start to develop.

The same case happens with air ducts – as long as they are clean and work correctly, the air they circulate in your property will be safe and healthy. However, if they are clogged and dirty, they could pass toxins and other harmful elements through your property.

When air ducts are clogged, they cause HVAC systems to work harder, which could make them shut down after a very short period. Therefore, you should ensure that your air ducts are cleaned regularly to increase the efficiency of a HVAC system. Doing this could save you money in future.

When to Do Air Duct Cleaning

How often you clean your air ducts depends on the kind of environment around your house. Houses located close to the beach or desert locations accumulate a lot of moisture and dust. On the other hand, houses in urban areas accumulate dirt and smog from roads and highways. Nevertheless, the EPA recommends cleaning air ducts every 3 years to ensure the HVAC system works smoothly.

Air ducts are the pathways for cooled or heated air from your HVAC throughout your home. They are like the circulatory system of your house, making air duct cleaning very essential. However, since ductwork is mostly located out of sight, maintaining it is something that many people forget. Nevertheless, if you do not want indoor air quality problems, consider having your air ducts regularly inspected and cleaned.