Heat, energy & performance
A clean extract system is not just safer - it is cheaper to run. When resistance is low, the fan sits near its efficient operating point and the balanced supply air is not wasted. Let grease build and every part of that efficiency slips, so the same ventilation costs more.
The short answer
A clean extract system is not just safer - it is cheaper to run. When resistance is low, the fan sits near its efficient operating point and the balanced supply air is not wasted. Let grease build and every part of that efficiency slips, so the same ventilation costs more.
The detail
A kitchen ventilation system is a balanced pair: extract pulling air out and supply, or make-up air, feeding it back in at around 85 percent of the extract rate under DW/172. When both sides run at their design volumes, the fan works near its most efficient point and the conditioned make-up air actually does its job of tempering the room.
Grease unbalances that. As it raises extract resistance, the fan slips off its efficient point and the extract volume falls. The supply side, unless it is linked, keeps pushing conditioned air in - now poorly matched to an extract that cannot clear it. Energy spent tempering that supply air is partly wasted.
Duct velocity matters too. DW/172 sizes main runs at roughly 6 to 9 metres per second so grease stays entrained and moving rather than dropping out. A grease-narrowed duct changes those velocities, encouraging more deposition, which raises resistance further - a loop that steadily worsens efficiency.
Demand-controlled kitchen ventilation, added to DW/172 in the 2018 edition, saves energy by matching airflow to cooking activity. But it can only trim a system that is mechanically sound. Bolt smart control onto a greased extract and the control is trimming around a restriction that should have been cleaned away.
What it means for you
The cheapest airflow is airflow through a clean system. Before spending on drives, controls or new plant, the first move is to remove the grease that is quietly raising resistance and unbalancing supply and extract. A clean often recovers efficiency that no amount of control tuning can reach.
A balanced, clean system also protects the money you spend on make-up air. Conditioned supply air that is properly matched to the extract tempers the kitchen as intended, rather than being pulled through or under-used because the extract cannot keep pace.
Phoenix Duct Clean returns the whole extract path to its TR19 condition, so the airflow, the balance and the efficiency the system was designed around are all back in reach - and any smart controls you add work on a sound base.
The service behind the guide
Sibling guides
Why a kitchen turns stuffy mid-service · Poor extraction and air-con cost · Hotel multi-outlet extraction cleaning
Questions
Low resistance lets the fan sit near its efficient operating point rather than fighting grease. The extract and supply stay balanced, so conditioned make-up air is not wasted. Grease erodes all of that, making the same ventilation cost more.
Make-up air is the fresh supply that replaces extracted air, set at around 85 percent of the extract rate under DW/172. Balanced correctly it tempers the room; if the extract falls out of balance, that conditioned air is partly wasted.
Only partly. Demand control trims airflow to cooking activity, but it can only work efficiently on a mechanically sound system. On a greased extract it is trimming around a restriction that a clean should have removed.
Yes. DW/172 sizes ducts so grease stays moving rather than dropping out. A grease-narrowed duct changes velocities, encourages more deposition and raises resistance further, steadily worsening efficiency in a self-feeding loop.
Usually, yes. A clean recovers efficiency that control tuning cannot reach, and it gives any new drives or controls a sound base to work from. It is often the cheapest efficiency gain available.
Phoenix Duct Clean · by the numbers
A clean restores the efficient airflow your system was designed for. Book a TR19 clean.