This Aura Gravity Exhaust Ventilator has a 18 inch in diameter opening to the attic or plenum. It also has a 2 inch tall collar. Model number AV-18-C02 has 254 inches of net free area (NFA) and come with a 24″ x 24″ square shaped flange.
Aura Gravity Ventilators of 16 inch in diameter or larger are considered commercial sized. For those who are looking to ventilate their homes, they are encouraged to view roof vents that are smaller in diameter.
This large low profile ventilator is for asphalt shingle roofs only. If installed on the upper portion (no more than 2 feet down from the peak) of the roof, this product can go on a 3/12 to 5/12 pitch roof. For roofs that are pitched at 6/12 or greater, please notify the sales department when ordering your roof vents. Aura Gravity Ventilators can be modified to operate up to a 12/12 pitch.
The Aura Gravity Ventilator works like a roof turbine but with no moving parts.
Aura Gravity Ventilators rely on the Venturi Effect (the creation of an upward draft) when wind blows against the outer louvers.
Even the smallest breeze can create exhaust ventilation so that air is drawn out of the gravity vent. This movement of air is proportional to the wind speed, and is measured in cubic feet per minute (CFM). Wind speeds of 11 mph for a 18 inch Aura Gravity Ventilator, produces 634 cfm of air exhaust for attic ventilation.
Aura Gravity Vents are UL Listed and rated up to 50+ PSF or wind pressure above 200 MPH. Certified by Texas Department of Insurance, Florida State Approved & Conforms to the Standards of CALFIRE.