Cooker Hood Installation: Vented vs. Recirculating

A cooker hood is one of those jobs that looks straightforward and then takes 4 hours because nobody mentioned the cabinet has no power, the ducting bends 90° in the wrong place, or the existing hole is 100mm and the new hood needs 150mm.

Vented vs. recirculating: choose carefully

• Vented (ducted to outside): the best option for removing grease, steam and smells. Needs a duct path to an external wall vent. Far more effective at clearing the kitchen.
• Recirculating (with carbon filter): air passes through a carbon filter and back into the kitchen. No external venting needed. Easier to install but less effective — especially for steam.

Ducting basics

Ducting is rated by diameter: 100mm, 125mm and 150mm. Bigger is better — less restriction, less noise, more extraction. Use rigid ducting (PVC or aluminium) wherever possible. Flexible ducting is OK for short bends but every metre of flexi costs you 10-20% airflow. Keep total length under 3m and limit to 2 bends.

Power supply

Most hoods plug into a 13A socket inside the cabinet above. If your existing cabinet has no power, you'll need either a fused spur added by an electrician or a power feed pulled from a nearby ring main. I'll always check before drilling — nothing worse than installing a hood and discovering no socket.

Hood height above the hob

• Gas hob: 65-75cm above hob surface. Lower than 65cm and you risk heat damage to the hood electronics.
• Induction / ceramic: 50-65cm. Induction releases less heat upward so the hood can sit lower for better capture.
• Check the manufacturer minimum — it's always printed in the manual.

Vent through the external wall

The cleanest finish uses a wall vent (sometimes called a louvre cowl) on the outside, joined to the hood with rigid duct through the wall. Drilling through a single-skin brick wall takes a SDS drill and a 125mm or 150mm core bit. Cavity walls need an internal sleeve to bridge the gap. External vents should always slope slightly downward (5-10°) to prevent rain ingress.

Installing the hood itself

1. Mark hood position centred over the hob.
2. Drill mounting holes — usually 4 fixings into either the wall or the underside of the cabinet above.
3. Connect duct first (if vented), then secure the hood to its bracket.
4. Plug in, switch on, test all speeds and lights.
5. Run a flame test — light a match below the hood, the smoke should be pulled straight up.

Common mistakes

• Long flexible ducting routed through cabinets — kills airflow and traps grease.
• Wall vent installed too close to a window or vent.
• Carbon filter forgotten on recirculating hoods (they're sometimes shipped separately).
• Hood mounted too high — if it's above 75cm you'll get poor extraction.

When to get me involved

If your kitchen has no existing vent and you want a ducted install, that's a half-day job involving core drilling through brick, fitting an external louvre, running duct and securing the hood. I've done dozens across London — budget for the drilling, not just the hood.