Extractor fan - recirculating or external wall fan?

[TerrysNo2]

In our new kitchen we are having the hob in the island. We were going to have a downdraft extractor but we cannot duct externally through the floor as its concrete and would be a major job.

The alternative is to have it recirculating but i've heard that this can be rubbish. FWIW we were going to get an Elica downdraft.

As an alternative, can anyone recommend an extractor which could go in an external wall and do the job - if such a thing exists?

Thanks!

expelair do one

I would not bother with any recirculating one.

Fit one elsewhwere in the kitchen, but make it 60L/s, as opposed to 30L/s over the hob.

A recirculating hood can be an attractive kitchen ornament, but serves no other purpose.

It is possible to put a duct on the ceiling, or between the joists if they go that way. You can paint it to match the ceiling, or I suppose could disguise it as an oak beam. Rectangular duct looks better in a home. If you didn't have an island you could run it along the tops of wall cabinets.

Many people have boxed RSJs on their ceiling so maybe no big deal. Or you could have a false ceiling or put lamps on the boxing.

here is an example. A 150mm or bigger fan will be quieter and more powerful than a 100mm one (which are usually cheap rubbish).

Observe number the of cubic metres of air extracted per hour. A wall exttactor needs to be about twice as powerful as a cooker hood because it does not capture the steam and fumes as source.

There are lots more

A ducted hood will always perform better and keep your kitchen cleaner.

PigletJohn we have a boxed RSJ above the island - how would a fan fit into here??

I have no clue about these things so please explain to a layman

We've got a fan fitted flush with the ceiling and ducted to outside along the RSJ which runs across the ceiling. You don't really know it's there and it seems really quiet. It's similar to the one we have in our shower room but more powerful I think. It complied with building regs (signed off a couple of months ago). Don't bother with a recirculating hood (they aren't even legal for new builds). I hate the look of cooker hoods, am really happy with the in-ceiling fan.

be careful if you are thinking of ever putting a standard height cabinet over the hob (OP and anyone else reading this ) as there are rules about the distance allowed between hob and flammable surface above it . 750mm gap for gas . 650mm gap for electric . 450mm gap for induction . but if it's over an aga then there's even more to consider the depth of the wall units too ... it's complex stuff you know !!!

sorry posted this on the wrong thread ! but still handy to know !
Glad you have found a good downdraft for your island !

we have a boxed RSJ above the island - how would a fan fit into here??

Steel members have to be enclosed in a fireproof material, usually two layers of plasterboard, to protect then from the heat of a fire which would make them soften and collapse.

You could put a plastic duct beside the boxed-in RSJ and have the boxing extended to hide it. I think it would have to be separately boxed so no fire can get past the duct, but the plastering and decoration would make it look like a single box. If neatly boxed-in it would not be very visually intrusive. It would be best if the duct can be accessed through the end in case it ever needs to be cleaned. Have a slight slope to the outside so that any condensation (unlikely with an indoor duct) would run to the outside terminal.

I expect your existing box will be about 8 inches deep, that would be more than enough depth for a duct beside it.

thanks pigletjohn that's really helpful!!