Choosing an extractor hood for a large kitchen

A small kitchen forgives almost any hood: the volume is modest, the door is shut and the smell leaves quickly. An open-plan kitchen of several dozen square metres is a different problem — steam and grease spread across the room before they reach the filter, and settle on the soft furnishings. A large kitchen therefore does not need a more powerful hood, it needs a correctly sized one.

Size it by volume, not by floor area

The rule designers work with is simple: the airflow should cover ten to twelve complete air changes an hour. Multiply the floor area by the ceiling height, multiply the result by ten, and you have the lower bound in cubic metres per hour. Then add headroom for the duct: every metre of pipe and every bend takes part of the flow, and the figure from the datasheet, measured with no ducting at all, will never repeat itself in your kitchen.

Width and mounting height

A hood should be no narrower than the hob, and in a large kitchen preferably one size wider, so the flow catches the steam rising from the outer burners. The mounting height comes from the instructions for that particular model, and over gas it is always greater than over electric. An island hood works in harder conditions than a wall-mounted one: nothing channels its flow, so an island is sized with extra headroom.

The shape of the body matters as well. A classic chimney hood gathers steam into a wide cone, an angled one leaves more headroom, and a hood built into a cabinet hides behind a door and works exactly as well as the duct you gave it. A telescopic pull-out panel increases the capture area while you cook and disappears when the hob is off. In a large kitchen the choice is usually dictated not by the appliance but by the geometry of the room: where the duct runs, how high the ceiling is and whether the hood will cut across a window.

Ducted or recirculating

Ducting outside is always more effective, because the air with its steam and grease leaves the room for good. Where there is no duct, recirculation through a charcoal filter is what is left, and then a few things matter:

• a charcoal filter is a consumable, replaced on the manufacturer's schedule rather than when the kitchen starts to smell;
• the stainless mesh grease filter goes in the dishwasher, and it should go there regularly;
• in recirculation the moisture stays in the room — in an open-plan kitchen that is an argument for a duct;
• a round duct with smooth walls offers far less resistance than a flat one full of bends.

Noise, light and controls

In an open room the hood is heard from the sofa, so the noise level at the middle speed matters more than a maximum airflow you will rarely use. Look at the lighting as well: in a large kitchen it often becomes the main task light over the hob. Touch controls are easier to wipe clean, and a run-on timer finishes the job after you have switched off the hob and sat down to eat.

Collect three numbers — the volume of the room, the width of the hob and the length of the future duct — and the choice narrows to a handful of models. If the kitchen is still being designed, work out the duct before the ceiling is closed: rerouting a pipe later costs far more than choosing a different hood.