Three duct types
Kitchen grease, dry ventilation and laundry ductwork are three different jobs with three different hazards. Know which you have, and the right clean follows.
The short answer
Not all ductwork is the same job. Kitchen grease extract carries a fire risk from grease; dry ventilation ductwork carries an air-quality and efficiency risk from dust; laundry ductwork carries a fire risk from lint. Each has its own standard, its own cleaning method and its own cadence - so the first step is knowing which one you are dealing with.
Type one
Kitchen grease-extract ductwork gathers a combustible film of fat every time the cookline runs. The hazard is fire, and because it scales predictably with cooking hours, it has the most defined regime of the three: TR19 Grease, cleaned across the whole run from canopy through ductwork to the fan and discharge, at intervals set by use - roughly quarterly for heavy use, six-monthly for moderate, annually for light.
This is the duct type most operators already know about, because insurers and fire officers ask about it directly. It is also the one with the clearest pass or fail: grease-thickness readings in microns say whether the clean worked.
Type two
Dry ductwork is everything that moves air rather than grease - supply, recirculation and general extract serving offices, function rooms, corridors and plant. Its risk is quieter: dust, pollen, bacteria and mould building up and circulating, restricting airflow and dragging down efficiency. The internal surface area of a ventilation system is roughly a tenth of the floor area it serves, so there is a lot of surface for contamination to settle on.
Its standard is TR19 Air, aligned with BS EN 15780, which classifies cleanliness by use as low, medium or high and sets dust-deposit targets accordingly. Because nothing catches fire on a normal day, this is the duct type most likely to be forgotten - even though a heavy dust load is itself a combustion load.
Type three
Laundry and tumble-dryer ductwork carries lint - highly combustible, and quick to build up. As it accumulates it restricts airflow, which raises operating temperature and creates ignition conditions at the dryer's heating element; oil or emollient contamination on towels can add a self-heating hazard on top. Unlike grease, laundry ductwork has no single standardised matrix - cleaning is risk-based, driven by volume and build-up, with lint filters emptied every cycle and ducts cleaned far more often in busy commercial settings.
The common thread across all three is simple: an unmaintained duct is a liability. What differs is why - fire from grease, poor air and waste from dust, fire from lint - and so the clean, the standard and the paperwork differ with it. Getting the type right is how you get the maintenance right.
Questions
Kitchen grease-extract ductwork (fire risk from grease), dry ventilation ductwork moving air (air-quality and efficiency risk from dust), and laundry or tumble-dryer ductwork (fire risk from lint). Each has its own standard and cleaning cadence.
No. Grease extract follows TR19 Grease, dry ventilation follows TR19 Air aligned with BS EN 15780, and laundry ductwork is cleaned on a risk-based approach with no single standardised matrix.
Dry ventilation ductwork, because nothing catches fire on a normal day - yet dust build-up harms air quality and efficiency and adds a combustion load.
Lint is highly combustible and builds up fast, restricting airflow and creating ignition conditions at the dryer's heating element; oil-contaminated fabrics add a self-heating hazard.
Yes. We clean grease extract, dry ventilation and laundry ductwork, each to the appropriate standard, method and interval for that duct type.
Phoenix Duct Clean · by the numbers
Grease extract, dry ventilation or laundry ductwork - we clean each to the right standard. Tell us what you run and we'll set the regime.