What a Professional Kitchen Extract Clean Involves

Most people book a kitchen extract clean without ever seeing one happen, because it is usually done at two in the morning after the kitchen has shut. That is a shame, because knowing what a proper clean involves is the easiest way to tell whether you got one.

Here is the whole process, in order.

A quick note on scope before we start. This is a guide to what a professional clean involves, not a DIY manual. Kitchen extract work involves rooftop access, live electrical isolation, caustic chemicals and confined spaces. The filter cleaning your staff do is genuinely a staff job. The rest of it is not.

1. The Survey

Any decent job starts before the night of the clean. We walk the system and work out what we are actually dealing with:

• Where the duct runs go, and how long they are.
• Where the access panels are, and whether there are enough of them.
• Where the fan sits, and how we reach it.
• How heavy the grease deposit is, which drives how long the job takes.
• What is underneath the ductwork, because that is what has to be protected.

This is also when access problems surface. If a duct run has one panel at one end and nothing for fifteen metres, we tell you then rather than on the night, because the fix is to install panels and that needs planning.

2. Isolation and Protection

On the night, before anything is touched:

• The extract fan is electrically isolated and locked off. Nobody wants an impeller starting up with a hand near it.
• Gas appliances are isolated where required.
• Everything below the work is sheeted. Cooking surfaces, benches, floors, and any equipment that cannot be moved.
• Anything that could be damaged by water or degreaser is covered or removed.

A clean that leaves your kitchen needing a deep clean of its own is not a clean, it is a mess with paperwork.

3. Filters and Canopy

Filters come out and are degreased separately, usually by soaking. While they are out, the canopy itself gets done: the plenum behind the filters, the internal surfaces, the grease gutters and the collection cups.

The plenum is the part that matters and the part most often skipped. It is behind the filters, out of sight, and it collects everything the filters do not catch.

4. The Ductwork

This is the heart of the job and the part you are really paying for.

The duct run is opened at the access panels and cleaned section by section, working through the whole run rather than just the accessible ends. Depending on the deposit, that means scrapers, rotary brushes, and a degreaser suited to hardened grease and carbon.

The standard we work to is bare metal. Not “better than it was”, not “wiped down at the openings”. If you can still see a film, the job is not finished, because a film is fuel.

Vertical risers get particular attention. Grease runs down them and pools at the bottom of the rise, and that pooled deposit is one of the most dangerous parts of the whole system. Our guide to grease duct fire risk explains why.

5. The Extract Fan

The fan is where a lot of cheap cleans quietly stop.

A proper fan clean means the housing, the impeller and the blades. Grease builds up unevenly on an impeller, which throws it out of balance, which wears the bearings, which eventually costs you a fan. Cleaning it is maintenance as much as compliance.

If the fan is on the roof, that is roof access, edge protection and often a permit. It adds time to the job, and it is one of the reasons rooftop systems cost more to service than internal ones.

6. Reassembly and Verification

Panels go back on with their seals intact. Filters go back in the right way round, which sounds obvious and is a surprisingly common error. The fan is unlocked and run up.

Then the system is checked: it starts, it runs without unusual noise or vibration, and it is moving air the way it should. If airflow verification is on your compliance schedule, this is when it is recorded.

7. The Documentation

The paperwork is not an afterthought. For compliance purposes it is the deliverable.

What you should receive:

• Before and after photographs of each part of the system, not one generic shot.
• A written report naming what was cleaned, what was found, and what was not accessible.
• A note of anything that needs attention: missing panels, a worn fan bearing, damaged ductwork.
• The date, and who did the work.

This is what your IQP looks at when it comes time to sign a Form 12A, and what a council auditor asks for. A clean with no documentation is worth very little to you at BWOF time.

How Long It Takes

A single canopy cafe system with good access might be two to three hours. A multi canopy restaurant kitchen with long duct runs and a rooftop fan can be a full night, sometimes two.

The variables are system size, how much grease is in there, and how easy it is to get at. A system cleaned on schedule is dramatically quicker to clean than one that has been left for three years, which is a large part of why regular servicing costs less over time.

Questions Worth Asking Your Provider

• Are you cleaning the full duct run, or only what is reachable from the canopy?
• Does the price include the fan housing and impeller?
• What do I get in writing afterwards?
• What happens if you find something that needs fixing?
• Will the clean meet what my compliance schedule requires for SS9?

If the answers are vague, keep looking. Our guide to choosing a duct cleaning company goes into what separates a real operator from a bloke with a pressure washer.

For background on the system itself, kitchen extract systems explained walks through the components. To book, see kitchen extract cleaning.