Cooker Hoods Buying Guide

John Lewis cooker hood

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

Extract or recirculate?

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

Extraction

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

Benefits

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

Disadvantages

  • 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

Recirculation

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

Benefits

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

Disadvantages

  • Recirculates some heat and moisture back into the kitchen
  • The cost of regularly replacing charcoal filter
  • Decreased airflow rate due to charcoal filter placement in front of motor

Filters

If the air is recirculated through the cooker hood, this is done through a  grease then a charcoal filter.

All cooker hoods will come supplied with a grease filter, but not normally a charcoal one. These can normally be obtained through the manufacturer’s website or their dedicated accessories and spares shop. A recirculation kit may also be required containing additional essential components 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 much you use your cooker hood. The grease filter can either be replaced if it’s paper, or washed – usually in the dishwasher - if of the permanent metal variety.


You’ve decided to extract – what next?

Ducting

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.

Extraction rate

To work out the extraction rate you’ll need of the hood you wish
to buy, calculate the volume in cubic metres of the room and multiply x12. 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 minium extraction rate of 540m³/hr.


Noise

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.


More information

You'll need to position the hood at a minimum of 65cm above
a gas hob, or 43cm from an electric 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



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