calculating extraction rate in kitchen

[Coffeepotclaire]

I'm trying to work out what extraction rate I need for my size kitchen but some websites say L x W x H x 6, 10 or even 12!  6 being for the average extraction rate at setting 3 and 12 being the power boost setting.  If I multiply the size of my kitchen by 12  ( ie 6.6m x 4m x 3m x 12)  I would need an extractor with a power boost rate of 950.4m3/hr!!!!  I don't even think you can get an extractor that powerful!  Can anyone tell me what formula I be using as the the most powerful extraction rate I can find (at power boost setting) is about 640m3!  Help greatly appreciated. 

[PeterW]

Why are you calculating extract rate ..??

 

Kitchen extraction is a standard value depending on whether it is above a hob or not and set in Part F. It’s 60l/s if not above the hob, or 30l/s if above/adjacent 

[Coffeepotclaire]

Oh, I thought you had to calculate  the cubic metre size of your kitchen in order to determine how powerful an extractor you need for that size room!  Have I completely misunderstood????

[TonyT]

1 hour ago, Coffeepotclaire said:

Oh, I thought you had to calculate  the cubic metre size of your kitchen in order to determine how powerful an extractor you need for that size room!  Have I completely misunderstood????

https://www.justfans.co.uk/acoustic-commercial-kitchen-inline-exhaust-fan-mps-p-2011.html?sort=1a

would work but would be noisy just like a commercial canopy. 

 

[Coffeepotclaire]

Thanks Tony.

[ryder72]

On 11/05/2021 at 15:52, Coffeepotclaire said:

I'm trying to work out what extraction rate I need for my size kitchen but some websites say L x W x H x 6, 10 or even 12!  6 being for the average extraction rate at setting 3 and 12 being the power boost setting.  If I multiply the size of my kitchen by 12  ( ie 6.6m x 4m x 3m x 12)  I would need an extractor with a power boost rate of 950.4m3/hr!!!!  I don't even think you can get an extractor that powerful!  Can anyone tell me what formula I be using as the the most powerful extraction rate I can find (at power boost setting) is about 640m3!  Help greatly appreciated. 

 

 

 

You are not wrong with this approach.

 

The building control figure of say 60l/sec  is a flow rate irrespective of the size of the kitchen. This is to ensure that mould doesnt become a problem and is completely inadequate from a perspective of clearing a room of smoke and odour created from cooking. Another example of building control stuck in the dark ages.

 

multiplying your room volume less volume of goods in it (like kitchen units) and multiplying this by 12 will give you extraction rate you would require to rapidly remove smoke and odour from grilling steaks etc. Multiplying by 6-8 is what you need for normal cooking activity. However also remember that this figure makes sense in a self contained kitchen. Open plan living has challenged extraction capabilities. Venting hobs are changed the way extraction requirements are defined.

 

Lets say your room is 6m * 5m * 2.4m = 72 m3 * 12 = 864 m3. Ideally you want your extractor to have an extraction rate of 864 m3/h. You are right, very few extractors have this sort of capacity, but also remember that an extractor that does 600 m3/h will still do the job, just slower. Try and find one that gets as close to the target figure as possible and you will get best possible extraction performance.

 

Dont tie yourself up in knots if you cant find the extractor. Its not the end of the world.

[SteamyTea]

600m³ of air has a mass of about 750 kg. Not a lot to move a few metres in an hour when you think if it.