When airflow is more than 80 cubic feet per minute, what should the duct piping be equivalent to?

When airflow exceeds 80 cubic feet per minute (CFM), it’s crucial to choose the appropriate duct piping size to maintain efficient airflow and minimize resistance. A duct size of 4 inches in diameter is typically recommended for handling airflow in that range due to its ability to manage the volume of air effectively.

Choosing a 4-inch ID pipe allows for a smoother flow of air compared to smaller diameters. Smaller pipes can lead to increased friction and turbulence, which can create inefficiencies in the system and increase the static pressure within the duct. This can result in less effective radon mitigation performance, as proper airflow is essential for reducing radon levels indoors.

In context, while larger diameters may allow for even more airflow, they can also be excessive and unnecessary for airflow rates just above 80 CFM. Thus, opting for a 4-inch ID pipe strikes a balance between efficient airflow and effective radon mitigation without being overly large for the task.