Kitchen extractor fans - help please!!

[Lodgecockers]

It's very boring ... but we need to sort this out. New kitchen/diner is 50 sqm so I believe needs quite a strong extractor fan. Induction hob in an island but it's almost impossible to duct a cooker hood as it's 8m to the external wall and there are RSJs in the way. Don't want a recirculating one I've been told. I think there's an option to have a fan on the external wall (so quite a long way from the hob), like a bathroom one but much bigger. Anyone done this and any experience of whether it's any good? If so, make/model that you would recommend would be much appreciated. Thank you!

No easy solutions then.

If the area is 50 sq m and assuming a ceiling height of 2.4m. Have about 120 cu m volume so need around 1500 m3/h extractor. Thats a pretty chunky unit.

If a direct ducting path is not available, the internal or external motor is not your real problem. The problem is finding the straightest possible path to the outside with minimal bends. In any case the 8m run you have is a very long one, so it may be a good idea to get an inline motor to aid your external motor. This way your extractor performs as effectively as possible. Use round 6 in rigid ducting if possible. If not use 6 in section rectangular rigid ducting of high quality. Make sure your motors are balanced. Having one more powerful than the other is not a good idea.

I would recommend Gutmann or Westin as the two best products for the job. However, please be warned that this isnt going to be cheap.

Ugghhh.... Thanks. I thought that was the likely outcome (difficult and expensive). What about just a fan on the wall like you'd have in a bathroom but a massive version of it? So nothing near hob itself. Is that even an option? Or are there any recirculating ones that are any good at all? Thanks for your help!

I think you are going to have to look at commercial kitchen extractor solutions. It will need a specialist custom solution. Your kitchen is as big as a commercial kitchen.

Recirculating fans just don't work.

Could you vent vertically straight out of the roof?

In the final analysis you might have to move the hob nearer a wall..

you might be able to put a duct between the joists of the floor above.

Or maybe reconsider where to put your hob.

Thanks for your help everyone. Unfortunately joists above have RSJs flush with a number of them so can't get a duct through. It may be possible to have just one right angled bend a metre from the fan and then a straight run to the external wall of 5.5 metres. Is this too long for ducting do you think? If we got a strong external motor? Thanks again for the advice.

it is a big kitchen and quite a long duct, and island hobs have more sideways drift due to air currents, so you will need a large and powerful hood; or a large hood with separate inline fan. Remember to have the fan where it is readily accessible for cleaning and maintenance. It should be high enough that nobody can bang their head on it without using a ladder.

Inline fans are generally quieter and more powerful than ordinary extractor hoods. They can run very quietly at low speeds, preferably coming on with the lighting for your island, and you can turn up the speed for frying or curries. Don't get one that you will be reluctant to turn on.

Thanks so much PigletJohn (and others). Really appreciate you taking the time to give me such good advice. I'll look for a powerful hood with an inline fan. I know what you mean about not turning it on - have had that in the past with a hood which sounded like a jumbo jet taking off!

Can you have an extractor mounted in the work surface near the hob and vent under the floor? You do not have to vent upwards.

They are called downdraft extractors and sit flush with the work surface when not in use. Quite a few are now available but not cheap, of course.

Downdraft extractors are against the very basic principle of physics. Heat rises. Once heat/odours have got past the extraction zone (and lot of it does) it disperses in the room and odours linger and grease settles. I would recommend a quality recirculation product from Gutmann or Westin over a downdraft.