Back Draft Shutter Ducting Part — Anti-Backflow Damper for Extraction Systems
Best for: Growers wanting odour containment and airflow protection when extraction fans are off
Our thoughts
This does exactly what it should — stops air flowing the wrong way when your fan's off, without creating a fuss about it. Simple, reliable, and the kind of thing that sits quietly in the background until you actually need it. Worth having in place.
A back draft shutter is a ducting component that prevents air from entering or leaving your grow space when your extraction system is inactive. Fitted inline between your duct fan and outlet, it uses spring-loaded damper blades that open when air is being extracted, then close automatically the moment the fan stops. In short: no backflow, no escaped odours, no stress during power outages or equipment failures.
How it compares
Back draft shutters sit at the foundation of proper odour control and system protection.
- Spring-loaded damper design opens freely under normal airflow, with negligible impact on CFM
- More reliable than gravity flaps, which can rattle or fail to seal properly
- Significantly cheaper than integrated connector units, allowing you to retrofit existing ducting
- Quieter operation than basic flap designs — no knocking or banging in wind
You're getting a critical safety component at a price that makes sense for any extraction setup.
Usage guidance
Installation is straightforward and works across most ducting types:
Installation position
Mount the shutter near the outlet point of your extraction system, facing the direction of airflow. Can be fitted horizontally or vertically without performance loss.
Connection to flexi ducting
Slide the shutter into your existing flexi duct and secure with a duct clip.
Connection to rigid ducting
Fit to rigid duct using a female-to-female coupling, then seal the joint with aluminium duct tape.
Multi-fan setups
Particularly useful in dual-fan systems with air-cooled fixtures. The shutter prevents air from being drawn backwards through cooling loops when your primary fan stops, while allowing your carbon filter fan to continue running independently.
Emergency protection
During power outages or scheduled maintenance, the shutter automatically seals your grow space. Combined with a carbon filter, this gives you an extra layer of odour containment when extraction isn't running.
Technical specifications
- Design: Spring-loaded damper blades (butterfly configuration)
- Material: Galvanised steel body with spring-loaded aluminium damper blades
- Available sizes: 4", 5", 6", 8", 10" & 12" (100mm to 300mm ducting)
- Pressure drop: Approximately 15 PA (negligible impact on fan performance)
- Build standard: EU manufacturing standard with quality welds and sealed joints
- Orientation: Can be mounted horizontally or vertically
- Installation: Compatible with flexi and rigid ducting via standard duct clips or female-to-female couplings
Who this is for
- Any grower running an extraction system with carbon filtration
- Residential growers in multi-storey properties where odour containment matters
- Growers upgrading basic setups with proper passive airflow protection
- Setups using air-cooled fixtures where dual-fan systems need backflow prevention
- Anyone planning for worst-case scenarios (power outages, equipment failure, maintenance downtime)
Particularly suited to growers who want to eliminate the risk of untreated air escaping during system downtime without overcomplicating things.
Our take
This is proper odour control infrastructure at a realistic price. It's not flashy, but that's the point — it sits in your ducting doing its job invisibly until the moment you actually need it. When your fan's off and air tries to backflow, it just closes. Simple.
If you're running extraction with a carbon filter and don't have backflow protection in place, good time to add one while clearance stock lasts. The kind of component that costs very little but saves you properly when things go wrong.
