Externally vented downdraft - any good?

[Flymeaway4]

We’re planning a kitchen extension and will have an induction hob in the island. Ceiling mounted extractor isn’t an option as ceiling is pretty low already. We’re taking up the floor anyway, so can vent it outside, as opposed to recirculating.

Can anyone share their real life experience of a downdraft? Is it as good as a conventional extractor, or should we redesign in order to fit a conventional one? Is it better to get an integrated hob and extractor, or separate? Any brands to go for or avoid? Thanks

We had one in our last house and I loved it. We were building from scratch so we were able to vent it under the floor and it had a very stylish silver box outside.
I have a loathing of overhead extractors, so it was a no brainer for me. I wanted clean lines in the kitchen, my hob was in my island so it worked really well.
We've just moved and I'm already mentally re planning the kitchen so I can get one in

I've just realised I didn't really answer your question. It certainly worked as well as we required. Having said that it was quite a big kitchen diner open plan space, so I guess some of the steam may have dissipated a bit anyway. Overall very happy with it

We have a Siemens one that pops up from our Island. There is a huge pile that runs under the floor and vents outside. It's brilliant. In fact, I can see the pans cooking from where I am sitting and all the steam is fully being sucked into the extractor!

Pipe not pile!

@DirtyDancing how ‘huge’ is your huge pipe? We are taking up the floor for underfloor heating anyway, so logistically we are good to fit a pipe, but it’s an old house with a low ceiling and limited foundations, so we can’t dig too far or build up too much.

So you had no issues with condensation? I keep reading about issues due to forcing hot air downwards, but maybe you just need to make sure the extractor is good enough to cope?

@cashmerecardigans don’t suppose it was paired with underfloor heating, was it? Just trying to figure out how the floor should be built up, considering both the extractor and underfloor heating

Thank you

Just asked DH and he described it as the same size as a tumble dryer piped on vented machines. In fact it basically looked like one. It aaa dig into the ground. One thing to consider is the unit takes up space in the island so you loose a draw effectively.

We don't even have extractor on highest setting 90% of the time. Level 2 is fine. Level 3 is a bit noisy tbh

Good to know, thanks @DirtyDancing

@LittleOverWhelmed your kitchen is beautiful!

We may be upgrading our kitchen next year, and in my research/planning I've initially discounted downdrafts thinking they're inherently inefficient. This thread certainly makes me reconsider (subject to proper installation)

We got a neff down draft extractor basically this one www.neff-home.com/uk/productlist/hobs/induction-hobs/T58TL6EN2 though ours is flexi zone.

It is quite noisy on full but I’ve been wondering if the fitter forgot to fit the sound deadening bits.

It’s very effective.

We ended up getting a local fabrication place to make a steel duct to go under the screed. Rather than the plastic supplied ducting. There’s one slight kink in it, so it’s not a straight run.

It wasn’t entirely straightforward but we had a good kitchen fitter who thought about it. The builders, who are good, were a bit foxed by it. And we needed to plan it into the process of putting screed down, and make sure the island position wasn’t going to change….

But it works well now it’s in. It does take up space in the island. Ours vents out the back do it needs half a cupboard space behind the hob, others vent straight downwards.

Not sure what happens if it stops working….

Thanks everyone, really appreciate the info!

I guess we really need to know which hob and/or extractor we want before laying concrete/screed, as that will determine the ducting we need, which needs to go in shortly. Hmmm, we’re building the extension now, but won’t be fitting the kitchen for another year, as we need to refurb the rest of the house too. What about if we err on the side of caution and go for slightly bigger ducting than we’ll likely need, ie. would it also be a problem if it ends up being ‘over-spec’?

@LittleOverWhelmed I like the look of the slimline ceiling mounted one, too, I’ll have a research as that could combat another issue. I’m trying to figure out where we would vent it to outside, as our plan had been to have the floor inside the kitchen flush with the ground outside (so there’s no step when you open the sliding doors), but I guess the ducting will need to be in the wall at ground level? In which case, there would need to be a step down going outside.

There's a step down from our extension to outside so yes, it comes out the wall into a flower bed.

@LittleOverWhelmed did some research and liked the idea of the slimline overhead one, but have discovered our rafters run in the wrong direction to accommodate it; the duct would have to run too far in either direction in order to reach outside.

So we’re back to the downdraft!

I like having the hob on the Island, but, quite honestly it would have been a lot easier to have it up against the wall!

Have you looked at recirculating ones - the pricier ones are supposed to be good and if you have a reasonably large space it's probably fine.

And once you've factored in price of ducting, hassle factor - then a recirculating decent one might not be that much more expensive.

The recirculating ones (I believe?) don’t get rid of water vapour and because it’s an old house we want to minimise humidity and the potential for issues with damp

We did have underfloor heating, although it was electric not hot water. I think the vent for the extractor went down first, concrete on top and we put the electric wiring on top.

@LittleOverWhelmed thank you, so much useful info! It makes sense what you're saying about the style of cooking. We use oven a lot, so it's usually not a big issue. But currently we have no extractor at all, so if anything is rendered or griddled on the top, the whole house stinks for a couple of days

@Justcannotbearsed I’m trying to work out where the ducting fits into the floor construction and alongside underfloor heating. So, does it fit on top of the insulation, like the underfloor heating does? If so, I guess we’ll have to try to loop the UFH pipes around the duct. Did you have it manufactured in steel, so it could take the weight of screed and flooring above? Or for another reason? Thanks again

@Flymeaway4 I appreciate this is 2 years on, but what did you go with? We are undecided between a ducted or recirculating vented hob on the island - would be good to know what you have done!

2 years? Wow, our renovation is still ongoing! It is a big project though.

We decided to go with vented. Everything I read told me vented is best and, as we have an old house with solid lime skimmed walls, we are very wary of moisture and issues with damp (recirculating only removed smells, moisture is fed back into the room). Given we were extending, it was a great opportunity to fit a vent, as we were digging anyway.

The hard part was that it meant we had to decide on the kitchen layout, at least the bones of it, well in advance. Since then, we’ve had to work around the location of the vent in terms of the finer detail of the kitchen layout, but we’ve made it work.

Overall, so far I’m glad we did it, although it does add an extra element to think about in terms of design. I’ve not yet tested it though, as the kitchen isn’t fitted til next month.