Canopy, filters & fan
Every extract fan needs cleaning, but where it sits changes how that clean is done. A roof-mounted fan and an in-line duct fan collect grease the same way, yet reaching them safely is a very different job - one involving work at height and weather, the other confined access inside the building.
The short answer
Every extract fan needs cleaning, but where it sits changes how that clean is done. A roof-mounted fan and an in-line duct fan collect grease the same way, yet reaching them safely is a very different job - one involving work at height and weather, the other confined access inside the building.
The detail
A roof-mounted fan discharges straight to atmosphere through a cowl at the top of the duct. It has the advantage of keeping the noisiest, greasiest component off the kitchen, but cleaning it means getting onto the roof. That brings work-at-height planning, safe access to the fan position, weather and daylight constraints, and the practicalities of carrying tools and collecting grease waste without it running across the roof.
An in-line fan sits within the duct run inside the building, often in a plant room, ceiling void or riser. It is out of the weather, but reaching it can mean confined or awkward access, working around other services, and protecting the surrounding area from the grease that comes out when the housing is opened. What is gained in weather protection is often lost in tight, obstructed access.
Isolation matters in both cases but plays out differently. Any fan must be electrically isolated and locked off before the wheel is exposed, because a fan that starts with someone's hands near the blades is a serious hazard. On a roof the isolation point may be at the fan; in-line it may be in a plant room some distance away, so proving the fan is dead before opening it takes more care.
Both mountings share the same cleaning goal: strip grease from the wheel, the housing and the immediate duct so the fan runs balanced and moves its rated air. The difference is entirely in getting safe, working access to do it - which is why the mounting should be known and planned for before the visit, not discovered when the team arrives and finds the fan three storeys up or buried behind ducting.
What it means for you
Knowing your fan's mounting lets the clean be scoped properly. A roof fan may need height-access equipment, a roof permit or a weather window; an in-line fan may need plant-room access arranged, other trades notified, or a ceiling section opened. Planned in advance, either is routine; discovered on the day, either can turn a clean into a wasted visit.
The mounting also affects whether the fan actually gets cleaned at all. It is precisely because roof and in-line fans are awkward to reach that they are the parts most often skipped and quietly marked done. A clean that treats the fan as in scope, with the right access arranged, is the difference between a genuinely complete system clean and one that stops at the last easy panel.
Whatever the mounting, the fan belongs in the same TR19 Grease scope as the canopy and duct, and its cleaning should be recorded with the same before-and-after evidence. Access is a logistics problem to be solved, not a reason to leave the dirtiest component in the system untouched behind a certificate that implies otherwise.
The service behind the guide
Sibling guides
Canopy vs full extraction cleaning · Why a canopy looks clean but isnt · New fit-out baseline
Questions
A roof-mounted fan discharges to atmosphere through a cowl and sits on the roof; an in-line fan sits within the duct run inside the building. They collect grease the same way but are reached very differently.
Because access differs. A roof fan means work at height, weather and roof-access planning; an in-line fan means confined or awkward access around other services. The cleaning goal is the same but the logistics are not.
It must be electrically isolated and locked off before the wheel is exposed. On a roof the isolation point may be at the fan; in-line it may be in a distant plant room, so proving the fan is dead takes extra care.
Neither is simply easier - each has its own access problem. Both are among the most-skipped parts of a system precisely because reaching them safely takes planning.
Yes. Roof or in-line, the fan is in the same TR19 Grease scope as the canopy and duct and should be cleaned and recorded with before-and-after evidence, not left out because it is awkward to reach.
Phoenix Duct Clean · by the numbers
We clean the whole path - canopy, filters, plenum, ductwork and fan - and verify the result to TR19 Grease. Call or email for a clear quote and a certificate you can show your insurer.