What is the maximum size opening in a residential air intake screen which terminates outdoors?

The maximum size opening permitted in a residential air intake screen that terminates outdoors is ½-inch. This size is regulated to ensure that the intake screen effectively prevents the entry of larger debris, pests, and other unwanted substances that could obstruct airflow or contaminate the indoor environment. A screen with a ½-inch opening strikes a balance between allowing sufficient air intake for ventilation needs and minimizing the risks associated with larger particles entering the system.

The importance of this restriction lies in maintaining both the efficiency of the heating and cooling systems and the overall air quality within the home. Larger openings could permit entry of bugs, leaves, or other contaminants, potentially leading to blockages or other issues within the HVAC system. Additionally, this regulation aids in preserving the integrity of the outdoor system components by reducing wear from external contaminants.