Signs & diagnostics
You cannot certify your own system, but you can keep an eye on it between professional cleans. A few simple, safe checks tell you whether grease is building faster than expected - and when to call the clean forward.
The short answer
Between professional cleans, a facilities manager or head chef can keep a useful eye on the extract system with a handful of simple, safe checks. The point is not to clean the ductwork yourself or to judge compliance - that needs a competent technician, measurement and certification - but to notice early if grease is building faster than the cleaning interval assumes. Monitoring the filters, having a careful look at an accessible panel, and staying alert to smell, sound and airflow tells you whether the system is on track or whether the next clean should be brought forward.
The safe checks worth doing
Start with the filters, because they are the accessible frontline and the fastest indicator. If they are saturating heavily between changes, grease is being produced faster than the system is containing it, and the duct behind them is receiving more than usual. Keep them clean and note how quickly they load. Where there is an easily reached access panel, a careful look inside with a torch shows whether the duct surface is lightly filmed or heavily coated - a rough but honest read.
Then use your senses across the working week. A greasy or rancid smell that keeps returning after surface cleaning points to grease inside the duct. A change in the fan's sound - a deeper hum, a rattle, more vibration - suggests it is working harder against a restriction. Weak capture, lingering smoke or a hotter kitchen all point to falling airflow. None of these is a precise measurement, but together they form a reliable picture of whether the system is holding steady or drifting toward an overdue clean.
Where the checks stop and a professional starts
It is important to be clear about the limits of self-inspection, for safety and for compliance. You should not be opening sealed ductwork, working at height on a roof fan, or trying to clean concealed runs - those are jobs for a technician with the right equipment and access. And you cannot measure grease against the TR19 Grease limits or issue the verification that insurers and the fire risk assessment rely on; that requires a qualified technician, deposit measurement and formal certification.
So the self-checks have a specific role: they are an early-warning system between certified cleans, not a replacement for them. Their value is timing - they tell you when the interval set by the last risk assessment is no longer matching how hard the kitchen is working, so you can call the clean forward rather than wait for the calendar. Used that way, monitoring makes the professional cleaning schedule more responsive without ever pretending to stand in for it.
What to do about it
Self-checks work best when there is a proper survey to compare against. A professional clean and measurement gives you a known starting point - the system verified below fifty microns - so your monitoring has something to measure drift against. When your checks suggest grease is building faster than expected, that is the cue to bring the next clean forward rather than push on to the scheduled date. Monitoring and professional cleaning are partners: one watches, the other acts.
Questions
You can monitor it safely - check the filters, look through an easily reached access panel with a torch, and stay alert to smell, sound and airflow. What you should not do is open sealed ductwork, work at height on a roof fan, or attempt to clean concealed runs; those need a technician with the right equipment and access.
The filters are the fastest indicator - if they saturate quickly, grease is building fast. Beyond that, a returning greasy smell, a change in the fan's sound, and weak capture or lingering smoke are the everyday cues that airflow is dropping and the duct is loading up. Together they form a reliable picture.
No. Compliance under TR19 Grease depends on measured grease levels and formal verification, which need a qualified technician and the right equipment. Your checks tell you whether to bring a clean forward; they cannot measure microns or issue the certification insurers and the fire risk assessment rely on.
Filters are worth checking as part of routine kitchen maintenance - often weekly in a busy kitchen - and the sensory checks are things to stay alert to across every working week rather than a set-piece inspection. The aim is to notice change early, not to run a formal audit.
Treat it as a cue to bring the professional clean forward rather than wait for the scheduled date. If the filters are loading fast, the smell keeps returning or airflow has clearly dropped, the interval is no longer matching how hard the kitchen is working - so it is time to call the clean forward.
Phoenix Duct Clean · by the numbers
Self-checks work best against a proper survey. We measure and clean to the TR19 Grease standard, then you can monitor confidently between visits - and call us forward if something changes.