Every duct collects dust, and some collect worse. Gemini AMPM cleans ventilation systems to TR19®, the BESA standard for internal cleanliness, and verifies the result against BS EN 15780. Supply air, extract, laundry and kitchen systems — cleaned, measured and certificated, not just wiped and invoiced. The dirt is real; so is the paperwork.
TR19® is the BESA guide to the internal cleanliness of ventilation systems — the benchmark UK insurers, landlords and enforcing officers actually recognise. It works alongside BS EN 15780, the European standard that assigns buildings a cleanliness quality class — low, medium or high — and sets the deposit limits each class allows. Offices, hospitals and food premises do not share a definition of clean, and the standards reflect that.
Why it matters is simple. Dust in supply ductwork degrades indoor air quality and feeds microbial growth; dust in any ductwork is fuel. The Workplace (Health, Safety and Welfare) Regulations require mechanical ventilation to be kept clean, and kitchen extract carries its own fire regime under TR19® Grease — measured, certificated and covered by our grease testing service.
We survey first, measuring existing deposit levels so the clean has a before as well as an after. Then the work: access panels installed where needed, mechanical brushing and high-power vacuum collection through supply, extract, laundry and bathroom systems, disinfection where microbial contamination demands it. LEV and specialist extract get the same discipline. Systems are worked in sections, so the building keeps breathing while we clean.
Verification is what separates cleaning from tidying. Post-clean deposit measurements are checked against the BS EN 15780 class your building needs, and the certificate records the numbers, not just the visit. For evidence you can see, our ductwork CCTV surveys capture the internal condition on camera — before, after, or both. You get a report your insurer, your auditor and your own eyes can trust.
BS EN 15780 sets the rhythm: the standard assigns your building a cleanliness class based on use — an operating theatre is not an office — and recommends inspection intervals for each. Inspection results, not the calendar alone, then trigger cleaning. Kitchen extract is stricter: TR19® Grease works from cooking hours, with heavy-use systems typically cleaned every three months. We will tell you honestly if your ductwork does not need cleaning yet.
They are partners, not rivals. BS EN 15780 is the European standard that defines cleanliness classes and the deposit limits for each; TR19® is the BESA guide to good practice that sets out how UK contractors should survey, clean, verify and certificate against those limits. A competent hygiene contractor works to both: 15780 says how clean the system must be, TR19® governs how the work gets done and evidenced.
No. Ventilation systems are cleaned in sections, isolating one run at a time while the rest keeps working, and most of our hygiene work happens out of hours — overnight in offices, between services in kitchens, around clinical schedules in healthcare. Systems are reinstated and running before the building fills up again. Where a shutdown genuinely cannot be avoided, you will know the date, duration and reason in advance.
A named engineer, not a call centre, comes back within 24 hours. Tell us the building and what you’re dealing with, and we’ll scope it properly.