Commercial Extraction Hood Sizing

Posted by admin 20/01/2017 2 Comment(s)

Please note that this is a reference guide. Relevant local council and national bulding regulations will also apply.

Commercial kitchen extraction ventilation is essential for well function food outlet or restaurant.  A commercial extraction system is composed of three main elements:-

  1. The Extractor Hood
  2. The Primary Filtration also known as baffle filters, older mesh filters are known to be a fire hazzard and are being phased out.
  3. A lip all around the extraction to ensure that condensate is retained within the canopy.
  4. A negative pressure fan ducting system
    • Ductwork
    • Fan Motor
    • Speed controller
    • Odour Control
    • Efflux or Directional Cowl


How to size an extractor hood

To calculate the extractor hood size required.  Simply take the size of the total cooking equipment and add 300mm (1Ft) on either end.


You have cooking equipment:-

2 450mm Fryers

1 900mm 6 Burner Range

1 600mm Flat plate griddle

Total Width = 2100mm Long

Add 300mm + 300mm = 600mm

Required Hood Length = 2100mm + 600mm = 2700mm Long Extractor Hood


Extractor Hood Overhang


How to size your extractor fan?

This is a bit more complicated, but in simple terms.  If there is a lot of ducting, odour control or large volumes of air to shift, then you will probably need a turbo prop fan.  If the kitchen air is simply being ejkected to the outside then a plate fan will you suit you very well.  Please feel free to pick our brains on which fan would suit you best.


Do you need make-up air or replacement air

DW/172 says yes it is always needed.  It can however be introduced by the following methods:-

  1. Natural ducted - as short as possible and at high level

  2. Mechanical input at maximum 85% the rest should infiltrate naturally.

It is imperative that the kitchen remains a negative pressure area, i.e air is drawn in from other areas than the kitchen.  In odour that odours do not escape from the kitchen into the restaurant area as an example

It is also important that the air is pre-filtered, as the fresh air will always be contaminated with bugs, insects, dust and other airbourne contaminates.

Fire Supression

Fire supression systems are a great bonus to kitchen safety and loss of property and profit.  If you are on the fence about fire supression systems then think about how much effort, time and money you have invested into your restaurant business.  And then consider what you could lose.  If you would like a free consultation, or a simple cost estimate. please get in touch.

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2 Comment(s)

Yucel Mehmet:
12/08/2018, 02:56:47 PM,

Hello,I am planning on opening a Pizza take away which will need a pizza oven and extraction?Best regardsYucel

27/05/2019, 01:57:28 PM

i have 3 different canopy sizes. 1 off 2500 x 1050 mm 1 off 1500 x 1500 mm 2 off 900 x 1050 mmall the following canopies are connected to a duct via 600 x 300 mm opening.i need to calculate the airflow's thru each of the following canopies to get a final total to do a fan selection. how do i get the airflow's?

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