Frequently Asked Question

What is Net Free Area (NFA)?
Last Updated 10 years ago

Net free area is the standard of measurement used by the ventilation industry.  It is the unobstructed area of a ventilator through which air may flow.  For example, a C816 cornice vent (a 16” X 8” vent) has a NFA of 65 square inches. The hole cut for this vent would be 15 inches long by 7 inches wide.  The area of the opening would be 105 (15 X 7) square inches, but the net free area of a Lomanco C816 is 65 square inches. The louvered section and screening hinder the air flow and their net free area is lessened by their measurements. 

Please Wait!

Please wait... it will take a second!