Guide - TR19 Grease - UK-Wide
How much you cook decides how fast grease builds - and how often the system needs cleaning. Here are the volume bands, plus the measured way to turn your throughput into a TR19 interval.
The short answer
Two kitchens can cook the same dishes and still need cleaning months apart. Under TR19 Grease the deciding factor is throughput - how much you cook and for how long - because that is what governs how fast grease builds. As a volume-led starting point:
Those bands are the indicative table TR19 Grease offers when no measured readings exist yet. They are a place to start, not the final word - the moment your system has been surveyed, the grease reading sets the interval, and a high-volume cookline can land well inside three months.
Why volume, not size
It is tempting to judge a kitchen by its footprint or its menu, but grease accumulation tracks output. Every cover that comes off a fryer or a chargrill sends a fraction of airborne fat into the canopy and along the ductwork. Double the covers and you roughly double the grease the system has to carry, even if nothing about the room has changed. That is why a compact takeaway turning over hundreds of orders a night can out-load a far larger restaurant doing a gentle lunch.
Three things drive volume in practice:
The honest method
Guessing a band is fine for day one. After that, the credible way to set frequency is the daily-rate method TR19 Grease points to. On a survey the grease deposit is measured in microns at points through the system. Take the mean pre-clean reading, divide it by the number of days since the system was last cleaned or commissioned, and you have a daily accumulation rate. From there it is simple arithmetic to find the interval that keeps the mean below 200 microns - the threshold at which the whole system is due a clean.
A worked feel for it: if a busy grill loads to a mean of around 200 microns in ninety days, that is its natural quarter. Push the covers up by a third for a seasonal peak and the same system can reach 200 microns in sixty. The number moves with the volume, which is exactly why a fixed annual contract sold without a survey is the wrong tool for any kitchen that trades hard.
Why it matters
Over-estimate your volume and you pay for cleans you do not yet need. Under-estimate it - far more common - and grease builds past the safe limit for weeks before anyone notices, quietly raising the fire risk in the ductwork and weakening your position with an insurer if the worst happens. A grease fire on a system that was overdue, with no current certificate, is exactly the scenario that puts a claim in doubt.
The fix is not to clean more often for its own sake. It is to measure once, set the interval to your actual throughput, and review it whenever the volume changes - a new fryer, a busier season, a shift to higher-grease cooking. That keeps you compliant without over-servicing, and it gives you a dated certificate that matches what your kitchen really does.
Questions
For grease accumulation, yes. Build-up tracks how much you cook and for how long, not the floor area. A small high-output takeaway can load a system faster than a large kitchen doing a quiet service, which is why frequency is set by throughput rather than size.
On a survey we measure the grease deposit in microns at points through the system, take the mean and divide by the days since the last clean to get a daily accumulation rate. The interval is then set so the mean stays below the 200-micron threshold between cleans.
Often, yes. A strong seasonal peak can push a system up a whole band for a few months. We can build that swing into the plan so the interval tightens for the busy season and relaxes again afterwards, rather than holding one fixed date all year.
Grease builds past the safe limit before your next scheduled clean, raising the fire risk in the ductwork and leaving you with a certificate that no longer reflects the system. Measuring removes the guesswork so the interval matches what the kitchen actually does.
Yes. We clean overnight, early mornings or on closing days at no extra charge for out-of-hours work, so setting or resetting your interval never costs you a service.
Phoenix Duct Clean · by the numbers
Tell us how hard your kitchen trades. We will survey the grease load, work out your accumulation rate and set the right TR19 interval. No-obligation quote, UK-wide.