Heat, energy & performance
Summer stacks every pressure onto the extract at once. The ambient air is already hot, so there is less headroom to shed cooking heat; grease softens and spreads in the warmth; and trade often peaks. A system that limped through winter can fail visibly in a July heatwave.
The short answer
Summer stacks every pressure onto the extract at once. The ambient air is already hot, so there is less headroom to shed cooking heat; grease softens and spreads in the warmth; and trade often peaks. A system that limped through winter can fail visibly in a July heatwave.
The detail
In winter, the outside air is cool, so make-up air arrives cold and there is plenty of headroom to remove cooking heat. The room forgives an extract that is slightly under-performing. In summer that headroom vanishes: the supply air is already warm, so the same cooking load leaves the kitchen much hotter.
Grease behaves differently in the heat too. Warmer duct and canopy surfaces keep grease softer and more mobile, so it spreads and re-coats surfaces rather than staying put. A system that felt stable in the cold can foul more freely once the building warms, quietly raising resistance further.
Demand often peaks at the same time. Long summer evenings, events and busy terraces push the kitchen to full output for longer, so the extract is asked for its full design capture velocity more often - exactly when grease has left it least able to deliver.
The external context now matters as well. The UK Health Security Agency issues heat-health alerts through the summer, and HSE reminds employers that heat is a hazard to be risk-assessed under the Management of Health and Safety at Work Regulations 1999. Those alerts have run through the summer of 2026, and HSE is reviewing its temperature guidance, so the expectation on employers to actively manage kitchen heat is tightening rather than easing. A kitchen that cannot shed heat in a heatwave is both uncomfortable and a compliance concern.
What it means for you
The lesson is timing. An extract clean is most valuable going into summer, not coming out of it, because that is when the system has to work hardest with the least margin. A clean in spring or early summer sets the kitchen up for the season when it matters most.
Leaving it until the kitchen is already failing in a heatwave means booking a clean under pressure, during your busiest trade. Planning ahead of the hot months avoids that and keeps the room workable through the peak.
Phoenix Duct Clean restores full extract airflow so your kitchen goes into summer with its capture margin intact - ready for higher ambient heat, softer grease and peak demand together.
The service behind the guide
Sibling guides
Make-up air and airflow balance · Smoke and odour control · An extraction schedule you can prove
Questions
Higher ambient heat leaves less headroom to shed cooking heat, warmth keeps grease softer and more mobile so it spreads, and trade often peaks. All three hit at once, exposing a system that coped in cooler months.
It can spread it more freely. Warmer canopy and duct surfaces keep grease softer and mobile, so it re-coats surfaces rather than staying put, quietly raising resistance in a system that felt stable through winter.
Spring or early summer, before the hot months. That sets the kitchen up with full capture margin for the season when the extract works hardest, rather than booking a clean under pressure mid-heatwave.
Yes. HSE treats heat as a hazard to risk-assess under the Management of Health and Safety at Work Regulations 1999, and the UK Health Security Agency issues heat-health alerts. A kitchen that cannot shed heat is a real concern.
You end up booking a clean during your busiest trade, under heatwave pressure, with the room already struggling. Planning the clean ahead of summer avoids that and keeps service workable through the peak.
Phoenix Duct Clean · by the numbers
Summer is when your extract works hardest. Book a TR19 clean before the peak, not after.