The Airvent Wall Outlet Gravity Flap 100mm White (415454) is a compact external vent cover designed to terminate 100mm round duct runs at the outside wall. The gravity-operated flap mechanism opens automatically when airflow from the extractor fan pushes it outward, then falls shut under its own weight when the fan stops — blocking backdrafts, wind-driven cold air, insects and debris from re-entering the duct. Manufactured from durable weather-resistant plastic, it is suitable for external wall mounting on all building types. The face plate measures 140 × 140mm, neatly covering a standard 100mm core-drilled hole.
100mm
Spigot diameter
140×140mm
Face plate
45mm
Spigot depth
81g
Weight
3 Years
Warranty
Passive Protection — No Maintenance Required: The spring-less gravity flap has no moving parts that can rust or break. It opens and closes purely by the pressure differential between the airflow and gravity — making it a highly reliable, maintenance-free component for the lifetime of the ventilation installation.
Installation Note: For correct operation the flap must be installed vertically on an external wall so the flap hangs freely and closes under gravity. Installing horizontally on a flat roof or soffit will prevent correct operation. Use suitable exterior-grade fixings appropriate to the wall substrate.
Gravity-Operated Flap
Unlike spring-loaded shutters, the gravity-operated design requires no spring tension to close. The flap hangs vertically at rest, sealing the duct outlet. Airflow from the fan pushes it open; when the fan stops, it falls back under its own weight. No springs means no rust or fatigue failure over time.
100mm Spigot Connection
The 45mm deep rear spigot provides a generous push-fit connection for both flexible and rigid 100mm ducting. Secure with a jubilee clip or foil tape for an airtight, vibration-resistant joint. Compatible with all standard 100mm ventilation accessories.
Weather-Resistant Construction
Moulded from UV-stabilised plastic that will not discolour, warp or become brittle under prolonged sun exposure. The white finish maintains its appearance on rendered, brick or UPVC-clad wall surfaces for the duration of the 3-year manufacturer warranty and beyond.
Keeps Pests and Debris Out
When the fan is off, the closed flap creates a physical barrier against insects, spiders, small rodents and wind-blown debris entering the duct run. This is especially important in summer when ventilation ducts can become routes for pest entry if left open or only covered by a louvred grille.
Technical Specifications
| MPN |
415454 |
| Brand |
Airvent |
| Connection Diameter |
100mm (4") |
| Face Plate Size |
140mm × 140mm |
| Spigot Depth |
45mm |
| Closure Mechanism |
Gravity-operated (spring-less) |
| Shape |
Square face / round spigot |
| Colour |
White |
| Weight |
81g |
| Mounting |
External wall (vertical surface) |
| Warranty |
3 years (manufacturer) |
| Suitable For |
Kitchens, bathrooms, utility rooms |
Frequently Asked Questions
What is the difference between a gravity flap and a cowled outlet?
A gravity flap uses a hinged flap that hangs closed under its own weight and is pushed open by airflow — offering a tight seal when the fan is off and low resistance when it is running. A cowled outlet uses an overhanging hood to deflect rain and wind but typically relies on a spring-loaded backdraught shutter rather than gravity for closure. Gravity flaps are lighter and simpler; cowled outlets (like the Domus 4902W) provide superior rain protection in exposed locations.
Can I use this outlet with PVC or aluminium flexible ducting?
Yes. The 45mm spigot accepts both PVC flexible hose (such as Airvent 401897) and aluminium flexible ducting (such as Manrose 1010) by a push-fit connection. Secure with a jubilee clip. It is also compatible with rigid 100mm PVC or PVCu round duct sections.
How is the gravity flap fixed to the wall?
The face plate is drilled for screw fixing to the external wall surface. Insert suitable wall plugs into the masonry, position the plate over the duct hole, and fix with screws through the mounting holes at the plate corners. For cavity walls, ensure the duct protrudes flush with the outer skin. Apply a bead of exterior silicone sealant around the perimeter of the face plate for weatherproofing.
Will it work in windy locations?
The gravity flap works by airflow pressure overcoming the weight of the flap. In very exposed, high-wind locations, a strong prevailing wind hitting the outlet face can temporarily hold the flap shut, restricting extract performance. For exposed gable walls or coastal installations, a cowled outlet with a damper (such as the Domus 4902W) provides better wind resistance. Gravity flaps are best suited to sheltered locations or when the duct terminates on a lee wall.
