Cost & commercial
It is tempting to think fewer cleans means a smaller bill. Grease does not work that way - stretch the interval and each clean gets harder, longer and dearer. The interval that fits your kitchen is usually the one that costs least over a year.
The short answer
The intuition that cleaning less often saves money is the most expensive mistake in this whole subject. Grease accumulates continuously while a kitchen cooks, so a longer gap between cleans does not mean less grease to remove - it means more, and harder to shift. Stretch the interval and each clean becomes a bigger job; keep to the interval your kitchen needs and each stays small and quick. Your annual spend is roughly how often you clean multiplied by how big each clean is, and the second number is the one neglect inflates.
The baseline intervals and what sets yours
TR19 Grease gives baseline minimum frequencies by daily operating hours: a heavy-use kitchen running twelve to sixteen hours a day around every three months, a moderate six-to-twelve-hour kitchen around every six, and a light two-to-six-hour kitchen around every twelve. Those are starting points, not the final word. The actual interval should come from a competent person's cleanliness risk assessment, taking in the type of cooking, seasonal menu changes and how the grease is really building - and inspections should not run more than twelve months apart regardless.
The reason the interval is set from evidence rather than habit is that the same nominal kitchen can build grease at very different rates depending on what it cooks. Char-grilling and heavy frying load a system far faster than lighter cooking, so two kitchens open the same hours can genuinely need different frequencies. Getting yours right is the foundation of a sensible annual budget.
Why stretching the interval costs more
Here is the mechanism that punishes neglect. As grease sits, it does not stay soft and wipeable - it thickens and carbonises into a hard, baked deposit that has to be scraped and worked off rather than brushed away. So a system cleaned late is not just dirtier; it is harder to clean, meaning more hours, more labour and more cost per visit. Push the interval far enough and the mean deposit climbs toward and past the two-hundred-micron trigger, so you are also out of compliance between cleans - carrying fire risk and exposure on top of the bigger bill.
Cleaning on time does the opposite. Each visit deals with soft, manageable grease, stays short, and keeps the system below the threshold throughout. More frequent, lighter cleans can genuinely cost less over a year than fewer heavy ones, because you never pay the penalty of a carbonised catch-up clean - and you are compliant the whole time rather than only just after each visit.
Budgeting the year around the right interval
For a predictable annual figure, start from a survey and a risk assessment rather than a target number of cleans. Establish the interval your grease load actually supports, cost each visit at its proper scope, and multiply out. Done that way, the spend is smooth and defensible, each clean is small, and you are never funding the extra work a neglected system creates. Trying to save by skipping cleans nearly always spends more in the end - the cheapest year is the one where the interval fits the kitchen.
Questions
Usually the opposite. Grease builds continuously, so a longer gap means more grease and harder deposits, making each clean bigger. Your annual spend is roughly frequency times the size of each clean, and neglect inflates the second number.
By daily hours: heavy use of twelve to sixteen hours around every three months, moderate six-to-twelve-hour use around every six, and light two-to-six-hour use around every twelve. These are starting points; a risk assessment sets the actual interval.
Because the same nominal kitchen builds grease at different rates depending on what it cooks. Char-grilling and heavy frying load a system faster than lighter cooking, so kitchens open the same hours can need different frequencies.
Grease that sits thickens and carbonises into a hard, baked deposit that must be scraped off rather than brushed away. A late clean is harder as well as dirtier, so it takes more hours and costs more per visit - and you may be out of compliance between cleans.
Start from a survey and risk assessment, establish the interval your grease load supports, cost each visit at proper scope and multiply out. The spend is then smooth and defensible, and you never fund the extra work a neglected system creates.
Phoenix Duct Clean · by the numbers
We survey your grease load, set the frequency a risk assessment supports, and keep each clean small and on time - so your annual spend is predictable and you are never paying for a neglected system.