Extraction

Cooker hoods, extractor hoods, noise machines, whatever you want to call them; they’re a necessary “thing” in the kitchen. In combination w...

Cooker hoods, extractor hoods, noise machines, whatever you want to call them; they’re a necessary “thing” in the kitchen. In combination with ducting (see the big post here!) they get the smell of your cooking and the condensation/steam and encourage the flow of fresh air in to replace that nasty stale stuff.

Starting from the high level view; there are two types; ducted or recirculation. You really, really want to go ducted - it may be more work BUT it’s the best mode of operation. Recirculation hoods use a charcoal filter to “neutralise” cooking odours and really play no part in reducing steam/condensation or stale air elimination.

Hoods come in a wide range of styles (and cost) and some are not even hoods - see downdraft extractors. For the portfolio we wanted something a bit different. We wanted to step off the path away from stainless and glass, rectangular designs and see what could be done with a bit of thinking.

The primary considerations were really:

Make the capture area big enough - no point doing this if all the steam, smells etc make their way past the hood(s)
Include some kind of lighting - this would provide task lighting across the domino hobs
Make sure the hoods would mate to standard ducting

Lighting

We chose an industry standard form factor AR111 bulb type. This is 110mm across with a point light source that fires upwards into a reflector assembly. They can be obtained with different lighting angles and, when going LED, different color temperatures. This decision was synchronous with the decision to opt for a round hood design.

The intent was to have the light source suspended inside the hood with the duct mating shenanigans immediately above which conveniently meant we could design a combined fixture that was both duct mating solution and light source. At this point we also added a further role to the combined fixture; hood clamp - the fixture secures the hood

Combined fixture with AR111 in-situ

Surface Area

Having opted for a round hood design we spent considerable time looking for a suitable design for the actual hood. In the end we were able to source some nice spun aluminium parts (if they remind you of, say a light shade, well that’s because they are albeit for industrial sized lights).

The advantage of the spun aluminium parts was the simplicity of customising them (we work with aluminum a lot) and of course weight which was most definitely a consideration when you see how we intended to suspend them over the work area

With the above design considerations and decisions made we produced some POC drawings for the primary complexity of this project; the combined fixture. There were a large number of considerations at play with this part not the least that we needed to produce two of them because our design called for twin hoods.

Flux capacitor Combined fixture - not an overly simple part

These were also very much a feature so the design had to be right, the intended installation meant that there would be no disguising them. This drove some crucial decisions around ensuring the correct visual “weight” of fixings, the numbers of fixings, chamfer sizing etc. It’s very much these little details that ultimately determine whether a successful outcome is obtained.

Machining the parts is extensively documented (photographically) in the albums linked at the end of this post and you’ll see we needed to carry out a lot of operations and invent some new techniques to make the combined fixtures.

The intent with the installation was to suspend them primarily from the duct work BUT this meant we needed to be aware of a couple of things;

The overall weight (hence our preference for using aluminium)
The requirement to deliver power to the AR111 light sources

During the duct installation it became clear that there was too much “slop” in the rubber sealed unions which would have prevented any chance of a quality alignment and we were also unhappy with the idea of puncturing the duct work to let power in (this was primarily a concern around how to make it look ok).

The solution was to machine a supplemental support collar which fitted around a straight duct coupler that was mated to the combined fixture. The collar, as you can see in the pictures, allowed us to drop a hollow rod from the ceiling, through the collar and into the hood - this solved all the issues. We used a couple of “tricks” to stop it looking like a compromise, bodge, what have you;

We only used one per hood which was possible because we could rely on the stiffness of the rod and fixture as well as the balancing effect of the 90 degree duct unions
The rods were kept small and set an offset so that they did not sit at exactly 180 degrees

Supplemental support bracket

The actual installation was not an easy one; positioning the drop rods took a high level of care due to the decision to crank the duct work meaning the hoods moved in an arc as they were adjusted for height (this also constrained how high/low the hoods could be). There was also an element that the entire installation required all components in place before any fine leveling/adjustment took place due to the combination of physical fixings and delicate balance

The observant will probably spot two things; No grease filters - we did not have these at the time we photographed the project and the other obvious things is no fan. So do they suck?

We didn’t want to use an inline fan primarily because there was no way of integrating one successfully into the design aesthetic and we also wanted to keep the overall noise levels down. Noise in extraction systems is really a combination of two things; the ducting (specifically it’s size, shape and the number of bends) and the fan. Our duct was relatively simple and not particularly long so our main concern was fan noise. We addressed this by using an exterior side wall mounted fan which is exactly as it sounds; a fan that mounts externally on the wall and connected directly to the duct.

Installed (sans grease filters)

This was a complex project but one we’re very proud of because it was really the first proper excursion into this kind of complexity. With multiple bespoke components, the integration of industry standard components and some challenging installation requirements it is a project we’ll remember for a long time.