What is not allowed to be installed at the duct or weather cap termination?

The choice indicating that screens are not allowed at duct or weather cap terminations is based on the specific functions and performance requirements of ventilation and exhaust systems.

Screens might seem useful for preventing debris and pests from entering the duct system; however, they can also cause unintended consequences. Screens can obstruct airflow and create pressure imbalances if they become clogged with dirt or debris. This obstruction can negatively affect the efficiency of the ventilation system and may lead to increased energy costs or reduced effectiveness in air exchange. Furthermore, screens can trap moisture, potentially leading to corrosion or other forms of damage in the venting system.

On the other hand, hoods, filters, and dampers serve vital roles in the proper functioning of duct systems. Hoods direct airflow and protect the system from environmental elements, filters improve air quality by removing particulates, and dampers control airflow within the system, making them essential components that help maintain efficient operation and safety.