Anyone here comment on the effectiveness or otherwise of hob downdraught extractors, specifically the Bora? In the process of a major refurb, and need to decide whether to duct up or duct down. Downdraught is neater, with no annoying canopy in sightline, but as heat rises logic says they cannot be as effective. Or are they?
Any opinions appreciated. 2011MY 4.4TDV8 Autobiography Baltic Blue
TVR Griffith
Alfa Romeo Mito QV

I’ve fitted a few different ones in customers houses inc my own, the ones with the extraction in the centre are better than the ones with the extraction at the edges that said if your steaming food neither are great at extracting the steam when the top of the lid is over 12” away, also you loose a lot of the cabinet below and the ducting can be a pain 2012 Range Rover Westminster 4.4 TDV8
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Definitely form over function. Having looked seriously at them, I ended-up going flush in the ceiling with a large Westin and a huge in-line fan. Not so easy to do unless you're in a bunglaow.  The older I get, the more I realise that people confuse wrinkles for wisdom

Also went with Westin, but just the filter set and lights in the flush ceiling fitting. I ducted that through the ceiling and up to the loft and mounted the inline fan in the loft which keeps all of the noise out of the kitchen. Works a treat. Was during a major project here and was able to put in a false wall in a bathroom above to hide all of the bathroom plumbing as well as the ducting for the kitchen extractor. Mike - MPx

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Never found extractors do much other than blow smoke around the room…..

Building regs need all new builds to duct out (or a big 6” fan in the wall somewhere..) I have installed pretty much all types, rise up downdraught types, in ceiling flush and canopies. The best I’ve found is the is flush in-ceiling type, with a 6” rigid duct to outside.

If you are thinking of putting the hob on an island then it’s virtually impossible to duct out a downdraught extractor so it would have to filter and recirculate, which is next to pointless…. There is nothing that can't be fixed with a hammer😜😜
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Thanks for all the help and advice. Still undecided - up draught or down draught, ducting is going to be a challenge with two foot thick walls! 2011MY 4.4TDV8 Autobiography Baltic Blue
TVR Griffith
Alfa Romeo Mito QV

Kitchen canopies both domestic and commercial evolved and are used because they work.

Ours works fine, ducted up through the ceiling to an outside wall, all smoke and steam efficiently removed. BMW i3 Electric Car
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My point is less that they do absolutely nothing but that they do nowhere near what they are supposed to do. We have a fan test kit so we can check the extractor performance once installed before they are tested for building regs. it’s all about the ducting, a kitchen fan should achieve a min of 30l/s if above or adjacent to a hob according to building regs, most extractors will just about do this, even with rubbish ducting, but the specs of the appliance will boast about how they can do 180 l/s. That is in free air with no duct….

Eg, the Neff extractor we just installed quoted 180l/s but when on the end of 3m of 100mm flexi duct it achieved 32 l/s which is a pass but marginal. The duct was nice and straight and not crimped etc.

My ceiling extractor ducted with 6” solid duct gets 76 l/s which is brill but it’s spec says 277l/s or 1000m3/hr.

We’ve been asked on the next house we are doing, to install an extractor hob, slightly worrying as it starts from a slightly lower performance point and will probably end up with similar losses.

Bathroom fans are another issue, even good branded fans are next to useless, so have a manrose fan in my utility and it gets 8l/s straight through the wall with solid duct…..so care is required when picking the exact fan for a particular use. There is nothing that can't be fixed with a hammer😜😜
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Interesting points for sure and I hear what you say about the drop in performance. From my perspective, the end user, if I have 4 pans of boiling water on the hob and the extractor successfully removes the steam from my kitchen that's a result I'm interested in. BMW i3 Electric Car
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northernmonkeyjones wrote:

Never found extractors do much other than blow smoke around the room…..

Building regs need all new builds to duct out (or a big 6” fan in the wall somewhere..) I have installed pretty much all types, rise up downdraught types, in ceiling flush and canopies. The best I’ve found is the is flush in-ceiling type, with a 6” rigid duct to outside.

If you are thinking of putting the hob on an island then it’s virtually impossible to duct out a downdraught extractor so it would have to filter and recirculate, which is next to pointless….

Where does the air come in for it 'flow' you would need an air inlet at the opposite side. It seems awfully complicated just to avoid a duct through the ceiling void. BMW i3 Electric Car
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It should, as it’s spec is 500m3 in free air, generally speaking a 6” fan is what is required if not using an over hob or canopy unit. when not positioned over the hob the fan needs to have better performance 60l/s rather than 30 over a hob. Short rigid duct will help, but if you are doing a refurb then it’s unlikely the LaBC will test it in any case, rather just look to check you have a 6” fan. There is nothing that can't be fixed with a hammer😜😜
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I use a downie by Elica. It’s weak if you’re used to quality overhead solutions. Weak but not useless. I would advocate a downdraft extractor coupled with a room extractor fan, but when I tried to upgrade our solution to include a room extractor for the kitten my wife rejected on aesthetic grounds (without evaluating and without me pushing).

In short, even if you upgrade the motor for a downdraught extractor it is working against gravity and they’re not especially effective. Aesthetically superior though for many installations. L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso