Heat, energy & performance
Most hot-kitchen fixes fail because they target the wrong thing. Winding the fan up, trusting an air-change figure, or ignoring the make-up air are all common instincts that leave the real cause untouched. Understanding what actually controls kitchen heat saves a lot of wasted effort.
The short answer
Most hot-kitchen fixes fail because they target the wrong thing. Winding the fan up, trusting an air-change figure, or ignoring the make-up air are all common instincts that leave the real cause untouched. Understanding what actually controls kitchen heat saves a lot of wasted effort.
The detail
The first myth is that turning the fan up fixes a struggling extract. It does not. If the restriction is grease in the filters and duct, a fixed-speed fan cannot pull air through it any faster, and a speed drive just burns cube-law energy trying. The clog is the problem, and only cleaning removes it.
The second is trusting air changes per hour as the measure of a good system. DW/172 treats 40 air changes as a comfort floor and explicitly says it should not be used as the basis for designing the canopy. A kitchen can hit an ACH figure and still fail to capture the plume at the appliances, which is what actually matters.
The third is ignoring make-up air. Operators often assume a hot kitchen is purely an extract fault, when the room may be starved of replacement air and going negative. Extract and supply are a balanced pair under DW/172; treating only the extract can leave the kitchen struggling for reasons the fan cannot fix.
The fourth is treating heat as a comfort nicety rather than a controlled quantity. Capture velocity, static pressure and duct velocity are the real levers, and they are all degraded by grease. A kitchen that manages those - through cleaning and balance - controls its heat; one that guesses at fans and thermostats does not.
What it means for you
The reliable approach is to work from the physics rather than the instinct. Confirm the extract is clean and pulling its design airflow, confirm the make-up air is balanced, and confirm the canopy is capturing at the appliances. Those checks address the real causes instead of the visible symptoms.
Cleaning is central because grease degrades every one of the real levers at once - capture velocity, static pressure and duct velocity. Removing it is the single action that restores the most performance, which is why it usually comes before spending on new fans or controls.
Phoenix Duct Clean restores the extract to its TR19 condition and can advise where make-up air or balance is also at fault - so you fix kitchen heat at its cause rather than chasing myths.
The service behind the guide
Sibling guides
The cooler-kitchen payoff · Keeping a kitchen cool in summer · Preparing for an extraction visit
Questions
Usually not. If grease in the filters and duct is the restriction, a fixed-speed fan cannot pull air through faster and a speed drive just wastes cube-law energy. The clog is the problem, and only cleaning removes it.
No. DW/172 treats 40 air changes as a comfort floor and says it should not be the basis for canopy design. A kitchen can hit an ACH figure and still fail to capture the plume at the appliances, which is what matters.
Because a hot kitchen instinctively looks like an extract fault. But the room may be starved of replacement air and going negative. Extract and supply are a balanced pair, so treating only the extract can miss the cause.
Capture velocity at the canopy, static pressure and duct velocity - all degraded by grease. Manage those through cleaning and airflow balance and the kitchen controls its heat, rather than guessing at fans and thermostats.
Confirm the extract is clean and pulling design airflow, the make-up air is balanced, and the canopy is capturing at the appliances. Cleaning usually comes first because grease degrades every real lever at once.
Phoenix Duct Clean · by the numbers
The cause is usually airflow, not the thermostat. Book a TR19 clean and fix the real lever.