Cooker hoods buying guide

Sealed heating systems, double glazing and insulation all stop the circulation of fresh air, so extraction is needed in kitchens to help get rid of moisture and odours caused by cooking. This quick guide will help you decide what’s best for your kitchen.

Extract or recirculate?

Most of the cooker hoods we sell can be set to either an extraction or a recirculation mode. Extraction should always be your preferred option, but here we look at the pros and cons of both types.

How extraction works

Steam and odours are removed from the kitchen to the outside of your house via ducting.


  • Removes airborne contamination – smoke, odours, etc - to the outside
  • No need to replace charcoal filters on a regular basis, therefore making the long term running costs cheaper
  • No charcoal filter in front of the motor means airflow rate is higher


  • Some kitchens don’t allow for extraction due to a lack of space or capacity to install the ducting
  • Additional initial costs, e.g. for ducting and installation

How recirculation works

A filter containing activated charcoal is used to remove odour and smoke from the air, before releasing the ‘scrubbed’ air back into the kitchen.



  • Can be installed pretty much anywhere – ideal if you can’t reach an outside wall with ducting
  • Cheaper initial costs as ducting is not required


  • Recirculates some heat and moisture back into the kitchen
  • Annual replacement of charcoal filter is necessary, which raises running costs
  • Decreased airflow rate due to charcoal filter placement in front of motor


If air is being recirculated through the cooker hood for release back into your kitchen, it is taken through two filters: a grease filter and a charcoal filter.

All cooker hoods come supplied with a grease filter, but not usually a charcoal one; these can generally be obtained through the manufacturer’s website or their dedicated accessories and spares shop. A recirculation kit, containing additional essential components, may also be required to ensure that odour-free air is returned into the kitchen.

The charcoal filter needs to be replaced every year or so, depending on how often you use your cooker hood. The grease filter can either be replaced, if it is a paper filter, or washed - usually in the dishwasher - if it is a permanent metal filter.


You’ve decided to extract - what next?


Ducting kits aren’t supplied with cooker hoods and can generally be obtained directly from the supplier. Alternatively, generic ducting is available from all good DIY stores. If the hood offers a choice of using 150mm or 120mm (with an adaptor collar) diameter ducting, try to opt for the 150mm ducting if your builder gives you the go ahead – this will offer a slightly improved airflow rate, since the ducting is a bit wider.

Rigid ducting will also offer improved airflow over flexible ducting (which often looks like the vent hose on a tumble dryer). This is because flexible ducting – even when pulled fairly taut – has ridges that slightly inhibit the flow of the exhaust air.

Which extraction rate do you need?

To work out the extraction rate you’ll need for your kitchen, calculate the volume of the room in question in cubic metres and multiply by 12. This is to allow for 12 recommended changes of air per hour.

Example: Your kitchen is 6 metres long, 3 metres wide and 2.5 metres high. Multiply the room’s length x width x height to get the cubic capacity: in this case 45m³. If you wanted 12 changes of air per hour, then the extraction rate required would be 12 x 45m³, which is 540m³. So any cooker hood you consider should have a minimum extraction rate of 540m³/hr.


The noise of the hood can be somewhat intrusive when on intensive or high speed, but a good tip, especially if you're eating in the kitchen, is to switch the hood on a few minutes before you start cooking to get air circulating in advance. You can then switch it off or to the lowest setting when you sit down to eat, and it will have done its job.

Essential information

You'll need to position the hood at a minimum of 65cm above
a gas hob, or 50cm above an electric hob.

It is important that you check with the manufacturer the minimum height required above your hob.

Our range

View our range of chimney hoods
Choose from a variety of finishes and styles.

Cooking appliances

Read our guide to cooking appliances