Duct Out or Recirculate: How Cooker Hood Ventilation Works

When you’re choosing a cooker hood for your kitchen, one of the biggest decisions you’ll face is how the hood handles the air it pulls in. Should it vent air outside (ducted), or clean and recirculate it back into your kitchen (recirculating)? Both options have their place — but they work very differently.

How Cooker Hoods Work — The Basics

Regardless of the type, every cooker hood works in the same first steps:

  1. A fan draws polluted air (steam, heat, grease, odours) from above your hob.
  2. The air passes through a grease filter, trapping heavy grease to protect the motor.

After that, what happens next depends on whether the hood is ducted or recirculating:

🔹 Ducted Hoods: Push Air Outside

With a ducted (or extraction) hood, all that kitchen air is pushed outside your house through a duct:

  • Steam, odours and airborne grease are removed from the kitchen completely.
  • Because the air leaves the home, humidity and cooking smells don’t linger.
  • There’s no need for carbon filters — only the washable grease filter needs attention.
  • This usually makes ducted hoods more effective overall, especially for frequent cooking.

Downsides: Ducting needs access to an external wall or roof, and installation can be more complex and costly.

🔹 Recirculating Hoods: Filter & Return

In a recirculation setup, the cooker hood doesn’t send air outside. Instead:

  1. Air first goes through the grease filter.
  2. Then it passes through an activated charcoal (carbon) filter that traps odours and some fine particles.
  3. The now “cleaned” air is released back into the kitchen.

This means the air stays inside your home, but with grease and smells reduced.

Advantages of recirculation:

  • Much easier to install, no holes in walls required.
  • Great for flats, apartments, or kitchens with no external wall.
  • Lower initial cost — no ducting or structural work needed.

But keep in mind:

  • Recirculation is less effective at removing strong odours and large amounts of steam — because the air just gets cleaned and reused rather than expelled.
  • Carbon filters must be replaced regularly (often every few months) to stay effective.
  • Airflow can be reduced and noisier because the fan works harder through filters.

Which One Should You Choose?

✔ Go Ducted If:

  • You want maximum removal of odours and steam.
  • You cook often or do high-heat / heavy frying.
  • You have access to an outside wall for ducting.

✔ Go Recirculating If:

  • You can’t install ducting (e.g., in a rental or mid-terrace apartment).
  • You want a simple, flexible installation.
  • Your cooking is light to moderate.

💡 A good rule of thumb: Ducted extraction is usually the best performance option — but if external venting isn’t possible, a recirculating hood gives you a practical alternative that still captures grease and reduces odours.