Extraction Canopies Explained, Sizing, Filters and Airflow
A canopy is the part of a commercial kitchen that decides whether the room stays usable. Get the extraction wrong and you end up with condensation running down walls, staff working in heat and grease smell that follows customers into the dining room. Get it right and the kitchen breathes properly, the air stays clear, and the kitchen passes its next inspection without argument.
Specifying a canopy is not just a question of size. It means choosing between wall, island and condense designs, deciding on filter type, thinking about lighting, and making sure make-up air and gas safety are dealt with at the same time as the extraction rate. DW172 sets most of the numbers that a good design has to hit.
Wall, island and condense: matching the canopy to the layout
A wall canopy sits against a wall behind the cookline and is the most common arrangement in UK kitchens, extracting from one side only. An island canopy is needed where the suite sits away from any wall, in the middle of the room, and has to capture the plume from both sides, which generally means a longer, heavier structure than a wall canopy of the same appliance run.
A condense canopy is a different job again. It sits over equipment that produces steam rather than grease laden smoke, combi ovens, steamers, boiling pans, and its priority is removing moisture before it condenses on ceilings and walls. The Parry CON1200 Condensate Canopy Steam Hood is built for exactly that, sitting over a steam heavy line where grease filtration is not the main concern. Where the job is a single, straightforward cookline against a wall, something like the Parry General Canopy Commercial Extraction Canopy covers a standard run without the added structure an island canopy needs.
Sizing the canopy: overhang, DW172 and airflow
Whatever the design, the canopy has to overhang the appliance line, typically at the front and both ends, so that the rising plume of heat and grease is captured before it escapes into the room. DW172, the industry guidance for kitchen ventilation, sets out the overhang distances and face velocities used to calculate the extract volume a canopy needs to move.
A long run of heavy, continuously used equipment needs more canopy length and a higher extract rate than a short run of light duty appliances. The Parry TT2175 Titan Heavy Duty Extraction Canopy suits a longer, busier cookline with several heavy appliances running most of the day, while the Parry TT1275 Titan Heavy-Duty Extraction Canopy gives the same build quality over a shorter run, better matched to a smaller kitchen or a single compact line.
Undersizing leaves smoke and steam escaping into the room. Oversizing wastes energy and pulls conditioned air out of the kitchen faster than it needs to. Working through the calculation properly at the design stage, rather than fitting whatever canopy happens to be the right shape, avoids both problems.
Filters and lighting: the parts staff touch every day
Baffle filters are the standard choice for grease extraction. Air is forced to change direction repeatedly as it passes through a series of angled metal baffles, and the grease that drops out of suspension runs down into a channel or tray rather than travelling further into the ductwork. Mesh filters clog far more quickly and offer much less protection against a grease fire spreading into the duct.
Filters have to come out regularly for washing, whether that is a dishwasher cycle or a soak in the pot sink, and a canopy that makes this awkward will simply get cleaned less often. Integrated lighting matters just as much day to day. LED fittings sealed against grease and heat let chefs see the pass properly and should be specified as part of the canopy, not added afterwards.
Make-up air, ducting and where a gas interlock comes in
Extraction removes a large volume of air from the kitchen, and that air has to be replaced from somewhere. Without a make-up air supply the room runs at negative pressure, doors become hard to open, and the extraction itself starts to underperform because it is fighting the pressure difference. This needs to be part of the design from the start, not something fitted in after the canopy is already running below its intended rate.
Where running ductwork to the outside is not practical, a recirculating canopy is an alternative. It pulls kitchen air through grease and carbon filtration and returns it to the room instead of venting it outside. The Lincat L3 Fume Filtration Unit | Recirculation Extraction Canopy suits a kitchen where structural constraints rule out an external duct run altogether.
Where gas appliances sit under any canopy, a gas interlock is expected. This is a system that cuts the gas supply if the extraction fails or the airflow drops below the rate the design relies on, so gas cannot run without ventilation working alongside it. It is a safety requirement that needs checking at installation and again at every service, not treated as optional.
How Advantage Catering Equipment can help
We design, supply, install and service extraction canopies as part of the wider kitchen, working through DW172 calculations against the actual appliance line rather than guessing at a size. Whether the job is a wall canopy over a single range, an island canopy over a central suite, or a condense hood over a steam line, we can survey the space and specify accordingly.
Call 01304 827272 or email sales@advantagecateringequipment.co.uk.
Sources: DW172, Building Engineering Services Association.