Green Building Forum - Very efficient but quiet kitchen hood extraction

Very efficient but quiet kitchen hood extraction

Shevek — Sun, 08 Jul 2012 14:30:34 +0100

Any suggested strategies for making sure our kitchen extract hood is super efficient but also very quiet? (we will also have MVHR)

Very efficient but quiet kitchen hood extraction

owlman — Sun, 08 Jul 2012 14:44:48 +0100

How about remoting the motor unit from the kitchen, i.e. in ducting some distance away. Mount it on rubber bushings to minimise noise vibration and make sure you get the right type of inline fan, and good pre-fan grease filtration.

Very efficient but quiet kitchen hood extraction

Joiner — Sun, 08 Jul 2012 14:45:35 +0100

I'm removing the standard extractor when I build a 'false' chimney breast around our 1100mm-wide extractor hood so that I can fit an inline Manrose extractor in an insulated chamber (accessible for maintenance) to reduce the noise and perhaps convince the wife that it needs to be used...

http://www.manrose.com/specifications/man50inlinecent.pdf

(And as owlman posted a few seconds before me... retaining the filters in the extractor hood!)

And found these in the 'new products' section whilst I was looking to post the link...

http://www.manrose.com/specifications/flatchannelacousticdamper.pdf

http://www.manrose.com/specifications/fireairvalves.pdf

Very efficient but quiet kitchen hood extraction

PaulJ — Sun, 08 Jul 2012 15:52:57 +0100

If the outside wall is not on a main elevation, fit an external extractor.

Very efficient but quiet kitchen hood extraction

Sprocket — Sun, 08 Jul 2012 16:14:56 +0100

This is especially true for MVHR ducting but can also important for extractors.
To have maximum extraction and minimun noise it is important to

1) Use wide ducting. This reduces flow velocity (so less noise from ductwork) and reduces back pressure on the fan (so fan has to work less hard and makes less noise). Fitting a reducer and using narrow tubing can push noise levels up considerably and reduces effectiveness.

2) Use rigid smooth bore ducting (plastic is good). Use as few bends as possible and join duct sections with external joints (not slightly narrower pipe fitted inside). If you must use flexible ducting anywhere keep it as short as possible and don't reduce size at flexible ducting. The zig-zag internal surface of flexible ducting increases flow resistance and turbulence.

3) Use as few bends in ductwork as possible.

4) Keep filters clean.

We recently re-did our kitchen extractor. The original installer refused to do it properly (when asked to have another go with wider pipe because it was too noisy) saying it would make no difference because it's just meant to be that noisy. You could not have a conversation in the kitchen when it was operating.
When we opened it up we found a 200->100mm reducer and 100mm flexible ducting so we replaced it with 200mm rigid plastic ducting and the exact same extractor is now lovely and quiet. On lowest setting it seems pretty silent and even on max it is still very easy to talk over.
The extractor did come with the 100mm reducer in the box however the small print in the installation did say to stock with 200mm pipe for lowest noise and max efficiency.

Oh and less important for cooker extractor perhaps but in the case of MVHR very long pipe runs can cause resonance that greatly amplifies and selectively filters any noise in the system. It can be a good idea to check for this before sealing everything up and comitting to final positions and vent styles. We've got two almost idential and very simple MVHR installs here (both Xcell 270BP) but the first one we did has one long (20m) straight pipe run to the internal outlet duct. It is quite noisy at that outlet although it is well away from the MVHR unit. The second install has all very short ducts (all < 1m) and is silent.

Very efficient but quiet kitchen hood extraction

woodcutter — Sun, 08 Jul 2012 17:29:25 +0100

Not sure if I can recommend a firm on this site or not but I am sure someone will let me know.
I make and install bespoke kitchens and when we need advise or have an extractor problem we always use a firm call Westin, see www.westin.co.uk

Very efficient but quiet kitchen hood extraction

finny — Sun, 08 Jul 2012 17:51:29 +0100

As above, but you did ask.. trepol from Denmark, super powerful, as good as silent. you can smoke a cigarette near it and watch it suck it in! Probably not the cheapest hood in the world!

Very efficient but quiet kitchen hood extraction

john_connett — Tue, 10 Jul 2012 13:17:34 +0100

Definitely not the cheapest hoods in the world, either, but Berbel make a wide range of well engineered products:
http://www.berbel.de/uk/know-how/our-mission.html
I have their firstline built-in hood (recirculating) which is electrically linked to the boost on my MVHR.

Very efficient but quiet kitchen hood extraction

fostertom — Wed, 11 Jul 2012 12:49:20 +0100

'Super powerful'? Assuming that means enormous airflow rate, where's the air coming from in an airtight building (can't rely on any normal MHRV system to supply that much) and is the heat being recovered from that airflow?

Instead of 'super powerful', cd be looking at 'super efficient' instead, meaning ways (not yet commercially developed) to capture smells, steam, fat vapour, much closer to source e.g plumbed-in to the pan lids, or mini hoods flexibly positioned close above ea pan. Air speed is necessary - must exceed the speed of backward-propagation of volatile substances driven by partial vapour pressure, not bulk-air movement. Small 'intake aperture' (i.e. frontal area between pan rim and mini-hood rim) gives smaller volume flow for given air velocity, capturing same amount of heat, hence the outgoing airflow is smaller volume but hotter, hence easier/more efficient to capture heat from.

Better still, go veggie, stop frying, get civilised instead of vaporising quantities of stink and grease all the time.

Very efficient but quiet kitchen hood extraction

djh — Wed, 11 Jul 2012 13:39:39 +0100

Posted By: fostertom'Super powerful'? Assuming that means enormous airflow rate, where's the air coming from in an airtight building

Usually in an airtight building with MVHR, the hoods are recirculating, not extracting the air outside. So they can be as powerful as you like. And as noisy, since you've got both the intake and the exhaust!

Very efficient but quiet kitchen hood extraction

fostertom — Wed, 11 Jul 2012 14:54:58 +0100

Is 'recirculating' what the guys are discussing above? Don't think so - 'greenies' to a man, they're talking about powerful extract!

Very efficient but quiet kitchen hood extraction

RobinB — Wed, 11 Jul 2012 16:11:17 +0100

Since they say they will have MVHR in the opening question, reciruclation would be the only sensible way to go.
Only PaulJ seems to mention extraction to the outside. Anything for recirulation needs really good filters - and then you could send this gale out into a room for drying the washing.

Very efficient but quiet kitchen hood extraction

djh — Wed, 11 Jul 2012 16:44:42 +0100

Posted By: RobinBthen you could send this gale out into a room for drying the washing

Except won't it be quite humid having sucked up all the steam from the cooking?

Very efficient but quiet kitchen hood extraction

RobinB — Wed, 11 Jul 2012 16:52:41 +0100

fair point ...but you'll have the lids on to save energy, no?

Very efficient but quiet kitchen hood extraction

fostertom — Wed, 11 Jul 2012 17:44:45 +0100

Lo-energy cooking, incl dealing with fumes and waste heat, is the last big hurdle to be tackled in domestic energy use (even more so for commercial cooking). Great, untapped potential, and stuff someone can sell too!

However, like lo-energy lighting, it will only save energy in summer, because the reduced 'incidental gains' contribution to winter space heating will have to be supplied instead by the space-heating system.

In a Passihaus, that means the 'backup' heating system, already deprived of 'incidental gains' from lighting (thanks to LEDs) and less consumptive appliances and electronics, will become near-full-time, unless serious year-round (incl Dec/Jan) solar space-heating is designed-in.

Very efficient but quiet kitchen hood extraction

andyman99 — Sat, 28 Nov 2015 16:43:05 +0000

Posted By: JoinerI'm removing the standard extractor when I build a 'false' chimney breast around our 1100mm-wide extractor hood so that I can fit an inline Manrose extractor in an insulated chamber (accessible for maintenance) to reduce the noise and perhaps convince the wife that it needs to be used...

http://www.manrose.com/specifications/man50inlinecent.pdf" rel="nofollow" >http://www.manrose.com/specifications/man50inlinecent.pdf

(And as owlman posted a few seconds before me... retaining the filters in the extractor hood!)

Sorry old thread I know, but just wondering if you went ahead with this and if so how successful it was?

Very efficient but quiet kitchen hood extraction

gyrogear — Sat, 28 Nov 2015 23:07:06 +0000

Posted By: fostertomwhere's the air coming from in an airtight building

+1

Perhaps out of the fireplace, or down the wood-burner stove pipe, or via the Crawlspace Ventilation Grilles, or perhaps via the leaky garage internal door, and last but not least, through the sewer connections ?

gg

Very efficient but quiet kitchen hood extraction

Shevek — Sat, 28 Nov 2015 23:28:00 +0000

Very efficient but quiet kitchen hood extraction

Shevek — Mon, 06 Feb 2023 19:17:43 +0000

Has there been any innovation in this area since my original post? (geez, over 10 years ago!!)

I was just reading this from 2020:
https://passivehouseplus.ie/magazine/insight/hell-s-kitchen-why-cooking-can-destroy-indoor-air-quality

"A dialogue has begun between the largest manufacturer of range hoods and Shermanâ€™s Lawrence Berkeley National Laboratory. Heâ€™s optimistic that the next iteration of ASHRAE 62.2 will include a capture efficiency requirement."

Very efficient but quiet kitchen hood extraction

Simon Still — Tue, 07 Feb 2023 09:34:53 +0000

Posted By: john_connettDefinitely not the cheapest hoods in the world, either, but Berbel make a wide range of well engineered products:
http://www.berbel.de/uk/know-how/our-mission.html
I have their firstline built-in hood (recirculating) which is electrically linked to the boost on my MVHR.

Not new - this post was from 2012 - but I fitted one of their Ergoline hoods and it's exactly what people are saying is needed upthread.

https://www.berbel.uk/the-berbel-principle/functional-principle/

- recirculating (so you're not pumping heat to outside)
- cyclone approach to removing the oil/fat from the extract air (which is your main hood objective)
- large (refillable) carbon filter to remove smells (secondary objective) - only needs refilling every 3 or 4 years
- very high quality fan motors for quiet.
- if you do want extract they do an insulated, self closing vent designed for airtight house use (I seem to remember something about adding a sensor so that it knows you've opened a window as well)

One of the biggest issues with cooker hoods is the motor is very close to your ears when in use so a remote motor (or even the down draft extractors (though I'm dubious they are truly effective) which mean the motor is below the hob)

Very efficient but quiet kitchen hood extraction

Shevek — Tue, 07 Feb 2023 10:25:19 +0000

That is very cool, I like it. So you obviously find it very effective? How much was it?

The extraction version would be fine for where I am now (in Portugal), although I doubt we'd be able to fit the self-closing vent, because our current kitchen hood extracts into a pipe/shaft going up to the roof, shared by all flats below and above us!

Very efficient but quiet kitchen hood extraction

Simon Still — Tue, 07 Feb 2023 16:26:24 +0000

Posted By: ShevekThat is very cool, I like it. So you obviously find it very effective? How much was it?

The extraction version would be fine for where I am now (in Portugal), although I doubt we'd be able to fit the self-closing vent, because our current kitchen hood extracts into a pipe/shaft going up to the roof, shared by all flats below and above us!

They're really not cheap, but a completely different product to any other cooker hood I've seen. We got ours in 2015 from this place in Germany (pre-Brexit and a period of favourable exchange rates at the time)

https://www.ascasa.de/berbel:.:84:2.html?MODsid=ijm3ffi5n1tl3loegq9a1gjsj0

Very efficient but quiet kitchen hood extraction

revor — Tue, 07 Feb 2023 17:28:56 +0000

Thought our Westin flush to ceiling extractor was expensive, British made. Not connected to MVHR have a boost button under kitchen counter for when fan in use, is a bit noisy but extracts very well set up in recirculation mode.