Things You Should Know Flexible Ducting

Ducts are channels which are present inside devices such as heaters, coolers, air-conditioners, exhaust fans, kitchen chimneys, etc., for taking in and removing air. They are an essential component of any electrical device as they ensure proper ventilation of air without which system will be unable to function properly and may even damage. Ducts are made up of various materials such as galvanized steel, aluminum, polyurethane and phenolic insulation panels, fiber-glass duct, flex, etc.  Flex i.e., commonly known as flexible ducts are coils made up of metallic wires which are covered by flexible plastic material to form a tube-shaped structure. Flexible ducting is a process by which these ducts are adhered to the electrical devices and help in their functioning.


Flexible ducts are available in various measurements and are made up of different materials. In United States of America, generally, glass wool is used as a mode of insulation in such ducts whereas in countries such as Australia, both glass wool and fibers of polyester are used as a mode of thermal insulations inside the ducts. The insulating material is in turn covered by a protected layer so that no heat is exchanged between the two. The protective layer is generally made up of polyethylene or PET. The ducts are quite long with their lengths ranging up to 25 inches. So, they are usually compressed by coiling to a length of around 5 inches and put inside boxes for transportation. The diameter of the duct ranges from 4 inches to 18 inches but the ones which are used more often range in a diameter from 6 inches to 12 inches.

How flexible ducts are used

Flexible ducting is generally done to join supply outlets of air to the strong network of ducts. The ducts are usually joined with the help of metallic bands or lengthy zip ties.

One major drawback of flexible ducting is there is a considerable amount of pressure loss through the flex which does not happen in other kinds of ducts. For this reason, while installing them, their lengths are kept moderately short which is sometimes even less than 15 feet. This is accomplished by reducing the number of turns of the ducts which automatically decreases their overall length.

Another important aspect of flexible ducting is that kinks in the flexible ducts are generally reduced or are fully omitted to keep their length short.

One advantage of flex is that that can withstand moderate to high negative pressures.

Things to follow while installing flexible ducts

  • The ducts should be sealed with Mastic sealants to stop the loss of conditioned air.
  • The ducts should also be properly insulated to prevent any entry or exit of heat from the surroundings.
  • The flexible ducts are easy to cut and can be easily inserted into the desired point. So, they should not be cut more than the length needed as that will reduce the airflow inside the ducts.
  • Kinks should be avoided on the flexible ducts as they disrupt the flow of air and lead to unnecessary bends and kinks which cause hindrance to the air flow.
  • Since the flexible ducts are light, they should be supported at regular intervals to allow smooth and uninterrupted passage of air without any obstruction. Care should also be taken so that the ducts do not shrink or bend in between and are stretched properly till the source.

Thus, like any other ducting, flexible ducting has its merits and demerits, but proper regulation and maintenance can help in smooth functioning of these ducts.


What do you think?


Written by ashleykinsela

Content AuthorYears Of Membership

Leave a Reply