Heat, energy & performance
The extract fan usually sits on the roof, out of sight and out of mind - which is exactly why its decline goes unnoticed. As grease raises the static pressure it fights, the fan draws more current, its bearings and motor run hotter, and its life shortens. The cost is real even though nobody sees it.
The short answer
The extract fan usually sits on the roof, out of sight and out of mind - which is exactly why its decline goes unnoticed. As grease raises the static pressure it fights, the fan draws more current, its bearings and motor run hotter, and its life shortens. The cost is real even though nobody sees it.
The detail
The roof fan is the engine of the whole extract, pulling air through every filter, duct run and bend below it. It was selected to move a design volume against a design static pressure. Everything downstream of the canopy - grease included - adds to the pressure it has to overcome.
As grease accumulates, the static pressure climbs. On a speed-controlled fan holding its airflow, that means higher speed and, by the cube law, sharply higher power. On a fixed-speed fan it means a shifted operating point, more current for less useful air, and a motor working nearer its limit than it was ever meant to.
Heat is the by-product. A motor drawing more current runs hotter, and bearings under higher load and higher temperature wear faster. The gradual result is a fan that needs its bearings or motor replaced years earlier than it should, on top of the extra energy it has been quietly consuming all along.
Because it is on the roof, none of this is visible from the kitchen. The first sign is often a breakdown at the worst possible moment, or an electrician noting the current draw has crept up. The underlying cause - grease raising the resistance - has usually been building for a long time.
What it means for you
An overworked fan is a slow-motion expense: more energy every hour, then premature parts and an unplanned failure. None of it appears as an obvious line item, which is why it is easy to overlook until the fan stops. The grease driving it is measurable long before that point.
Cleaning relieves the load. With the extract path back to TR19 condition, the static pressure drops to its design figure, the fan draws its design current, and the motor and bearings run at the temperature they were rated for. Life expectancy and energy use both return to normal.
Phoenix Duct Clean clears the whole path the fan has to pull through, so the engine of your extract is no longer labouring against grease it should never have carried.
The service behind the guide
Sibling guides
Why clean filters cut energy use · Heat, grease and the summer season · Mobile catering extraction cleaning
Questions
Grease raises the static pressure downstream of the fan. To hold airflow the fan draws more current and runs hotter, or on a speed drive spends cube-law energy. Either way it works nearer its limit than it was designed to.
The fan sits out of sight on the roof, so its gradual decline is invisible from the kitchen. The first sign is often a breakdown or an electrician noticing raised current draw, by which point grease has been building for a long time.
Yes. Higher current means a hotter motor, and bearings under higher load and temperature wear faster. The result can be motor or bearing replacement years earlier than expected, plus the extra energy consumed throughout.
It helps. Returning the extract to TR19 condition drops the static pressure to its design figure, so the fan draws its rated current and runs at its rated temperature - the conditions it was built to last under.
Often. Clogged-system monitors detect fouling by exactly this signal. If a fan is drawing more current at the same setting than it used to, accumulated grease raising resistance is a likely cause worth investigating.
Phoenix Duct Clean · by the numbers
Grease raises the load it fights. Book a TR19 clean before it fails at the worst moment.