Which type of duct system requires the shortest distance between duct supports?

Flexible duct systems are designed to be lightweight and highly adaptable, which means they can easily navigate around obstacles and fit into tight spaces. One of the advantages of flexible duct is that it can be supported at greater distances than rigid duct systems, but it also has specific requirements for support to maintain airflow efficiency and protect the duct from sagging. This flexibility allows for shorter distances between supports compared to metal or rigid duct systems, which need more robust support due to their weight and structural properties.

Conversely, metal and rigid ducts need closer support spacing to prevent bending, deformation, or potential damage owing to their heavier materials and less pliable structure. Insulated ducts, while also requiring support at defined intervals, follow similar principles to metal duct and rigid duct regarding support spacing. Thus, flexible ducts require the shortest distance between supports, as they are less impacted by gravity and can be securely held with less frequent support points than the others mentioned.