A flexible duct is a particular type of duct used in a general HVAC system. One of the advantages of the flexible duct is that it can be installed in tight places, in which standard ducts would be unable to fit. It can also be used to bend around circular or oval parts of a building structure. This can help to create an optimal location for the duct system, and make energy-use more efficient, while also insuring air quality in a home or building.
The flexible duct can be made of many different types of materials. Some are laminated with aluminum, which is considered to be a standard-quality substance. Spring steel wire helixes are also often used as a material, and generally make the product flexible and durable. Sometimes, polyethylene vapor barriers surround the duct in order to help with energy conservation. Many flexible ducts do not require any tools for cutting or fixing, which can potentially simplify installation.
The life expectancy of a flexible duct can vary. Most products are designed to last as long as the dwelling. This is a good option, because it means that ducts will not have to be replaced. General life expectancy usually varies from manufacturer to manufacturer.
Most ducts are manufactured to meet safety standards, such as air quality regulations. Other products emphasize that they are eco-friendly. Many manufacturers produce flexible ducts that burn but will not emit dangerous fumes in a fire. Other types of products have been tested to be fire-resistant.
Some flexible ducts can be damaged by ultraviolet light. They can become brittle or even break if placed too closely to lighting systems. Usually a manufacturer will clearly state, on the product's packaging, if the flexible duct is susceptible to UV light damage.
A flexible duct can be either insulated or uninuslated. This is an important difference, because insulated products can help conserve energy while assisting in the maintenance of clear air. Some ducts are thermally insulated with materials such as fiberglass. Products that employ fiberglass insulation, however, are not 100% formaldehyde-free, since all such insulation contains some amount of formaldehyde.
Many flexible ducts are insulated with antibacterial material. This can help prevent bacteria and other fungus from growing inside the duct, which can have negative health effects. There are also differences in how flexible ducts are packed for shipment to users. Most products will come in a standard size of 10 meters. They may also be packed in either cartons or polybags. This can be important in cases where flexible ducts need to be transported and there is a concern about a shortage of space.