When can downspout and light-duty rigid materials be used for duct piping?

Using downspout and light-duty rigid materials for duct piping is appropriate specifically at exterior locations on the pressure side of the Active Soil Depressant (ASD) system. This is primarily due to the nature of these materials, which may not be as robust as other options available for more demanding environments, such as interior ducting where structural integrity and air leakage are critical factors.

At the pressure side of the ASD system, the downspout and light-duty rigid materials can function effectively without the same level of stress and performance demands placed on them as they would be in more critical applications. This installation practice ensures they can handle the airflow required by the system while still meeting safety and efficiency standards.

The other contexts in which these materials are suggested for usage do not provide the necessary conditions to ensure adequate performance and safety. For instance, using them only indoors may lead to issues with moisture and degradation over time, as these materials are generally not designed for such exposure. Likewise, there's no specific requirement for these materials to be 2"x3", so this is not a valid reason for their use. Finally, utilizing them on the suction side of radon systems would not be suitable because the suction side typically requires materials that can more effectively manage the negative pressure