The 20 inch Aura Gravity Ventilator is 20 inches in diameter and has a 4 inch tall collar. The model number is AV-20-C4 and has 314 inches of Net Free Area (NFA). All 20 inch gravity ventilators come with a standard 26″ x 26″ square flange flashing.
This large low profile vent is only for asphalt shingle roofs. If installed on the upper portion of the roof, no more than 4 feet down from the peak, this roof vent can go on a roof with a pitch of 3/12 to 5/12 in climate zones 1-4.
20 inch diameter roof vents are commercial size, therefore, should be in commercial settings. For those looking to ventilate their homes, please view roof vents with a smaller diameter.
The Aura Gravity Vent works like a roof turbine but with no moving parts.
Aura Gravity Vents rely on the Venturi Effect when the wind blows against the outer louvers. As a result, this creates an upward draft allowing air to freely flow in and out of the vent.
Even the smallest breeze can create exhaust ventilation so that air is drawn out of the gravity vent. Therefore, wind speeds of 11 mph for a 20 inch Gravity Ventilator produces 881 CFM of air exhaust for attic ventilation.
For any questions please see the frequently asked questions page. If you still have questions, email the sales team at [email protected] or call 845-565-7770. If you are looking to determine the pitch of your roof, see the Roof Pitch Diagram.
The diameter size of all roof vents determines the Net Free Area, also known as the "NFA". NFA is the measured amount of opening each vent offers at each specific size. to be available for venting air through a specific vent size. The calculator below will find the overall number of vents needed to effectively ventilate the targeted attic space.
Once you have the area, the numbers shown below are the number of vents of that size which would ventilate the specified area with both 1/300 and 1/150 rule.
The roof vent calculation values shown above are for the exhaust portion of the roof. The same amount of net free air inches is needed for air intake as well. Proper roof ventilation consists of 50% air exhaust and 50% air intake.