Yes. We recommend that you use insulated flex duct in longer vent run applications to assist in keeping the humidity from condensing inside the duct and to help prevent the pooling of water, which can damage the core. When using air connector, there is no limit in length for bathroom exhaust compared to when using air connector in HVAC applications (14 feet max). The national codes, currently, do not have any reference to bathroom exhaust requirements to state otherwise.
Can Flexible Duct and Air Connector be used for bathroom/shower exhaust fans?
April 1, 2013
Yes. We recommend that you use insulated flex duct in longer vent run applications to assist in keeping the humidity from condensing inside the duct and to help prevent the pooling of water, which can damage the core.