When a duct is contained within a wall cavity, what is the maximum nominal diameter allowed for the duct?

In the context of the North Carolina Mechanical Code, when ducts are located within wall cavities, there are specific limitations regarding their size to ensure safe and effective operation. The maximum nominal diameter allowed for a duct contained within a wall cavity is 4 inches. This limit is established to prevent issues such as insufficient airflow, increased resistance, and potential obstructions that could arise with larger ducts in confined spaces.

Having ducts that exceed this diameter could lead to complications, including difficulty in installation, compromised structural integrity of the wall, and reduced efficiency of the heating, ventilation, and air conditioning (HVAC) system, therefore proper adherence to this size restriction is crucial for maintaining performance and safety standards in mechanical installations.