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What is an Air Duct?

Alexis W.
Alexis W.

An air duct is a square or round hollow conduit or tube usually made of sheet metal. The purpose of an air duct is to carry cooled or heated air into rooms. The ducts usually form part of a home or building’s air conditioning and ventilation systems.

The main heating and cooling source of the building is connected to air ducts. This cooling or heating source produces heat energy. The energy is pushed up through the air ducts, and is carried elsewhere in the building as a result of pressure.

A vent cover over an air duct.
A vent cover over an air duct.

When the air is carried through the air ducts, vents are strategically placed in rooms that require heating or cooling. The hot or cold air carried through the air duct blows out of these vents, providing a temperature adjustment to the room. In many cases, vents can be opened or closed at will to determine whether air will leave the air duct or continue through the ducts.

Air ducts can be prone to several problems. Since the ducts are located out of site in walls or along the ceiling, maintenance can be difficult. Many often forget to do proper maintenance as well, causing potential long term problems.

A ceiling vent leading to an air duct.
A ceiling vent leading to an air duct.

A leaky air duct, in which the connections between the ducts themselves or between the ducts and heater are not secure, can result in a tremendous waste of energy. Tubes may also have leaks as a result of natural wear and tear. Poor installation and design can also cause leaky ducts.

Most builders and HVAC technicians advise periodic cleaning of air ducts. The buildup of mold, dust and bacteria in air ducts can cause allergies and other respiratory problems. Proper air duct maintenance requires checking to ensure the ducts are clean and not clogged, and removing accumulated dusts from vents and grills where air ducts release air.

It is a relatively simple process to clean an air duct. The first step in the cleaning process is to remove the vent covers using a screwdriver. If present, remove air filters as well.

Wash and clean the insides of the duct including its walls and ceiling. Next, vacuum the vents and air ducts as far into them as possible. First tape the vacuum’s hose to the machine before doing any cleaning in the air ducts.

If dusty or dirty, air filters may also need to be replaced. Use a vacuum to clean the vent covers and to remove the build-up of dust particles that were caught in them. Change the air filters every month to maintain the circulation of clean air.

Exterior wall vent leading to an air duct.
Exterior wall vent leading to an air duct.

Homeowners may also hire a professional duct-cleaning service team who will clean the air ducts and vents, and eliminate visible vermin, mold, and dust. Professional air duct cleaners will also inspect and clean the entire cooling and heating system, including the fans, registers, coils, ducts, and coils. This process can keep the heating and cooling system in good working order.

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    • A vent cover over an air duct.
      By: vlorzor
      A vent cover over an air duct.
    • A ceiling vent leading to an air duct.
      By: Kevin Penhallow
      A ceiling vent leading to an air duct.
    • Exterior wall vent leading to an air duct.
      By: Tony Baggett
      Exterior wall vent leading to an air duct.
    • Sheet metal is commonly used to make air ducts.
      By: Kybele
      Sheet metal is commonly used to make air ducts.