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Duct cleaning - duct routing
How kitchen extract ductwork is routed - the path it takes from the canopy to discharge - is decided at the design stage, and it shapes the system's performance, fire safety and cleanability for its entire life. Get the routing right and the system works well and stays maintainable; get it wrong and you live with the consequences. Here is what good routing gets right.
The short answer
Good kitchen ductwork routing, decided at the design stage, gets several things right at once. It keeps the run as short and direct as practical, which helps airflow and reduces where grease can collect. It avoids long horizontal sections where grease settles and accumulates, favouring routes that let grease drain back rather than pool. It builds in access for cleaning throughout the run, so the whole system can be reached and maintained. It respects fire compartmentation and provides for fire dampers where the duct passes between compartments. And it discharges safely, away from where the exhaust could cause a nuisance or hazard. Because routing is fixed when the system is installed, getting it right at design stage matters - a badly routed system is hard and costly to fix later.
Routing is a design-stage decision
The routing of kitchen extract ductwork - the path it takes from the canopy over the cooking, through the building, to where it discharges - is decided when the system is designed and installed, and it is one of the most consequential decisions made about the system, because it shapes so much of how the system performs and behaves for its whole life. A well-routed duct supports good airflow, resists grease accumulation, and can be cleaned and maintained readily; a badly routed one fights the airflow, collects grease in awkward places, and is difficult to clean. And crucially, the routing is largely fixed once installed, so these consequences are lived with rather than easily changed.
This is why getting the routing right at the design stage matters so much. It is far easier and cheaper to route the ductwork well when it is being designed than to correct a poor routing later, when it would mean re-working installed ductwork through a building. So the design stage is the moment to get it right, thinking through the whole path of the duct with performance, fire safety and cleanability in mind. A little care at design saves a great deal of trouble over the system's life. Understanding what good routing involves helps ensure this design-stage decision is made well - because it is one you effectively commit to for the system's lifetime.
Short, direct, and grease-aware
Good routing keeps the run as short and direct as practical, because a shorter, more direct duct is better for airflow and gives grease fewer places to collect. A long, convoluted route adds resistance that the system has to work against, and every extra length and bend is more duct surface for grease to deposit on and more places for it to accumulate. So a direct route, minimising length and unnecessary bends, serves both the airflow and the grease management - the system moves air more efficiently and has less duct in which grease can build up.
Routing also has to be aware of how grease behaves, particularly regarding horizontal sections. Grease-laden air deposits grease as it travels, and long horizontal runs are where grease settles and accumulates, because it is not draining anywhere - so extensive horizontal ductwork tends to collect grease heavily. Good routing minimises long horizontal sections where it can, and where horizontal runs are necessary, considers how grease will behave in them - favouring arrangements that let grease drain back towards the source rather than pool in the duct. Being grease-aware in the routing means designing the path so that grease is less likely to accumulate in problematic places, which reduces the fire risk and eases cleaning. So the routing decisions about length, directness and horizontal runs are partly about airflow and partly about controlling where grease collects.
Access and fire safety
Good routing builds in access for cleaning throughout the run. Kitchen extract ductwork must be cleaned regularly to control grease, and cleaning requires being able to reach the inside of the ductwork along its whole length - so the routing has to allow for access points at suitable intervals and ensure the duct can actually be reached and cleaned everywhere. A route that runs the duct through inaccessible spaces, or that makes parts of it impossible to reach, creates sections that cannot be properly cleaned - a real problem, since uncleaned grease is a fire risk. So designing the routing with cleaning access in mind, throughout, is essential to a maintainable system. Access designed in at the routing stage is far better than trying to create it later.
Fire safety is the other major consideration in routing. Ductwork passes through the building, and where it crosses between fire compartments, it breaches the compartmentation - so the routing has to respect the building's fire compartments and provide for fire dampers where the duct passes between them, so the compartmentation is preserved. The routing should be designed with the fire compartmentation in mind, planning where the duct crosses compartment boundaries and ensuring fire dampers can be fitted there. Getting this right at design stage integrates the ductwork properly into the building's fire strategy, rather than the duct being a route that undermines it. So access for cleaning and respect for fire compartmentation are both things good routing designs in - the system laid out to be both maintainable and fire-safe.
Safe discharge, and getting it right
Routing also has to get the discharge right - where the extracted air, laden with cooking exhaust, is released. The duct has to discharge to a safe, suitable location, away from where the exhaust could cause a nuisance or a hazard - not, for instance, where it would blow back into the building, affect neighbours, or discharge somewhere problematic. So the routing includes planning the discharge point, ensuring the exhaust goes somewhere appropriate. This is part of routing the duct sensibly through and out of the building, and getting it wrong can cause ongoing problems that are, again, hard to fix once the system is installed.
Pulling this together, good kitchen ductwork routing gets several things right at once - short and direct for airflow, grease-aware to control accumulation, accessible for cleaning throughout, respectful of fire compartmentation with provision for fire dampers, and discharging safely. Because all of this is fixed at the design stage and lived with for the system's life, it is worth getting right when the system is designed, thinking through the whole path with these considerations in mind. The alternative - a poorly routed system - means ongoing problems with performance, grease, cleaning and possibly fire safety, that are difficult and costly to correct after installation. So the message is clear: routing is a design-stage decision that shapes the system's whole life, so invest the care to get it right then, because it is hard to fix later. Good routing designed in from the start is what gives a kitchen ductwork system that performs well, stays cleanable, and is fire-safe throughout its life.
The takeaway
How kitchen extract ductwork is routed - the path from the canopy to discharge - is decided at the design stage and shapes the system's performance, fire safety and cleanability for its entire life. Good routing gets several things right at once: it keeps the run short and direct for airflow and to give grease fewer places to collect; it is grease-aware, minimising long horizontal sections where grease pools; it builds in access for cleaning throughout; it respects fire compartmentation and provides for fire dampers where the duct crosses compartments; and it discharges the exhaust to a safe location.
Because routing is fixed when the system is installed and lived with thereafter, getting it right at design stage matters enormously - a badly routed system means ongoing problems with airflow, grease, cleaning and fire safety that are hard and costly to correct later. So the design stage is the moment to think through the whole path with performance, cleanability and fire safety in mind, investing the care to route it well. Good routing designed in from the start gives a kitchen ductwork system that works well, stays maintainable, and is fire-safe for its whole life - which is exactly why it is worth getting right before the ductwork goes in.
Questions
Because the path the duct takes, decided at the design stage, shapes the system's airflow, grease accumulation, cleanability and fire safety for its whole life - and the routing is largely fixed once installed. A well-routed system performs well and stays maintainable; a badly routed one is lived with, hard and costly to correct later.
Keeping the run short and direct, which helps airflow and gives grease fewer places to collect, and minimising long horizontal sections where grease settles and accumulates because it cannot drain. A direct, grease-aware route moves air efficiently and reduces where grease can build up problematically.
Because kitchen extract ductwork must be cleaned regularly to control grease, and cleaning requires reaching the inside of the duct along its whole length. Routing that runs the duct through inaccessible spaces creates sections that cannot be properly cleaned - a fire risk. Access designed in at the routing stage is far better than creating it later.
Ductwork passes between the building's fire compartments, breaching the compartmentation - so the routing must respect the fire compartments and provide for fire dampers where the duct crosses between them, preserving the compartmentation. Planning this at design stage integrates the ductwork properly into the building's fire strategy.
The duct must discharge the cooking-laden exhaust to a safe, suitable location, away from where it could cause a nuisance or hazard - not where it would blow back into the building or affect neighbours. Planning the discharge point is part of routing the duct sensibly, and getting it wrong causes ongoing problems hard to fix later.
Because it is fixed once installed and lived with for the system's life, and far easier and cheaper to get right when designed than to correct later, which would mean re-working installed ductwork through a building. A little care at design - thinking through the whole path - saves a great deal of trouble over the system's lifetime.
Well-routed ductwork with access designed in is far easier to clean thoroughly - and where a system is more awkwardly routed, our cleaning reaches the horizontal runs and bends where grease collects.
