Home improvement accessory designed to stop reverse airflow and cold draughts in domestic ducting. Peace of mind for homeowners who want warmer rooms and fewer chilly gusts from extractor vents. Is the NESVENT Backdraught Shutter Flap the easy-to-fit fix for standard 4-inch extractor ducts?
⚡ At a Glance
- • Airflow Control: Gravity-operated shutter flaps close to block reverse flow while opening for exhaust
- • Best for: Homeowners and landlords wanting to prevent cold air ingress through extractor ducts
- • Not ideal for: Non-standard duct sizes below or above 100mm without suitable adaptors
Pair of inline 100mm PVC backdraught shutter flaps for 4-inch ducting. Designed to stop backdrafts while allowing extractor airflow to exit freely.
Keeps cold air out - with 100mm PVC gravity flap
Gravity damper flaps are mounted inline and sit closed when exhaust flow is absent; air pressure from an extractor fan forces the flaps open to allow outward flow. PVC construction gives a lightweight, rigid edge that helps the flap seal against reverse flow.
Blocks cold draughts entering through extractor ducts, helping rooms feel warmer and reducing unwanted airflow. Particularly useful during colder months when reverse flow is most noticeable.
Quick to install - with standard 4-inch connector
100mm diameter matches common 4-inch ducting and flexible hoses, allowing a direct mechanical connection without bespoke adaptors. The inline format fits into existing runs so no major modification of duct layout is needed.
Allows straightforward DIY installation into standard extractor ducts without specialist tools or professional help, saving time on common repairs and upgrades.
Durable for regular use - with PVC construction
Manufactured from PVC plastic that resists wear and moisture exposure typical in ventilation systems, making the shutters suitable for long-term use in domestic and commercial settings. White finish suits most installations.
Provides a long-lasting, low-maintenance solution for preventing backdrafts, ideal for kitchens and bathrooms where persistent airflow reversal can be a problem.
✨ The 4 Key Reasons for NESVENT Backdraught Shutter Flap
- Compact inline profile — Allows installation in short duct runs and confined loft spaces
- Robust PVC build — Resists moisture and wear for reliable, long-term performance
- Standard 100mm diameter — Matches 4-inch ducts for a secure, snug mechanical fit
- Pack of two flaps — Provides coverage for two duct runs or a spare replacement
📋 Technical Details at a Glance
- Category: Home Improvement, Ducting accessory
- Brand: NESVENT
- Material: PVC plastic
- Colour: White
- Diameter: 100mm (4-inch)
❓ Frequently Asked Questions
Q: Will these fit my extractor ducting hose?
A: They are designed for 100mm diameter, which equals a standard 4-inch duct, and will fit common 4-inch rigid pipes and flexible ducting hoses.
Q: Are they difficult to install?
A: Installation is intended to be straightforward with a snug connection into the duct run, and user feedback notes they are easy to fit into 4-inch ducts without professional help.
Q: Are they suitable for long-term use?
A: Made from PVC plastic with a design aimed at durability, they are described as suitable for both residential and commercial use and have received positive comments about quality.
🏆 Our Verdict
Suitable for homeowners and landlords who want a simple, reliable way to stop cold air entering through extractor ducts. The inline gravity shutter design and PVC construction combine to block reverse flow while allowing exhaust air to pass. Strong build and easy installation make the pack a practical, long-term addition to typical 4-inch ventilation systems.
