Hertfordshire · Air handling unit cleaning
AHU Cleaning in Woolmer Green
Air handling unit cleaning for businesses, landlords and public buildings in Woolmer Green. BESCA Vent Hygiene Elite member, cleaning to BESA TR19® Grease.
- Dirty coils holding back the airflow
- Filters that are clogged or overdue
- Blocked condensate drains and slimy trays
AHU cleaning in Woolmer Green, done properly
The fan pushes every bit of air in the system, so dust on its blades and housing ends up in the airstream. Fan, housing and the surrounding panels are cleaned as part of the job, once the unit has been shut down and isolated. Common call-outs are for dirty filters cutting the airflow and drain trays holding standing water, on heating and cooling coils, drain trays and supply and extract fans.
Rural buildings with mechanical ventilation, such as care homes and country hotels, often keep their units in roof spaces or outbuildings, where filters and drain trays get forgotten.
Our accreditations include CHAS, SafeContractor and ISO 9001, and we are fully insured. On top of that, we are a BESCA Vent Hygiene Elite member, cleaning to BESA TR19® Grease, trading since 2009.
- Location
- Woolmer Green (SG3)
- Wider area
- Hertfordshire
- Paperwork
- Report and pictures after the visit
- Quotes
- Fixed quote, typically within a working day
- Working hours
- When your site is closed, plus a 24/7 line
- Call
- 0345 646 2711
- Page updated
- 30 October 2026
For landlords and multi-site operators
Facilities teams in offices, schools and healthcare sites book us too across Hertfordshire. Work can be phased by floor, building or site around the people who use them.
We regularly work with managing agents. Tell us the site, the work and the access arrangements and we’ll come back with a fixed quote.
What AHU cleaning looks like in Woolmer Green
Food Standards Agency data includes about 5 schools, colleges and universities and about 8 hospitals, care homes and childcare premises across Woolmer Green and its immediate surroundings (about a mile and a half). Many buildings of this kind have supply and extract ductwork that gathers dust and needs inspecting. About 25 miles out from central London, Woolmer Green is part of the South East area we work across. Visits are booked around your hours, evenings and weekends included. Woolmer Green’s nearest hospital, Queen Elizabeth II Hospital, is about 4.8 miles south. Clean air matters most where people are unwell, and that’s as true in a care home as in a hospital.
Wherever a school like St Michael's Woolmer Green CofE VA Primary School has ducted ventilation, a half-term visit keeps the work out of lesson time.
Woolmer Green is about 4 miles north of Welwyn Garden City, in Hertfordshire. Whatever kind of site you run in Woolmer Green, we can take on AHU cleaning. Visits can be booked for evenings, overnight or weekends so the site keeps running. Our Hertfordshire coverage runs to 381 places, Woolmer Green among them. London is in our area too, around 25 miles away.
Our technicians cover all of the SG3 postcode area for AHU cleaning and the streets around it. AHU cleaning is available to premises on London Road, Evergreen Close and New Court and nearby roads. Other places close to Woolmer Green include Oaklands (1 mile south-west), Datchworth (1 mile east), Knebworth (1 mile north), Bull's Green (1 mile south-east) and Burnham Green (1 mile south). We also work in nearby towns such as Hemel Hempstead (14 miles south-west), Stevenage (4 miles north), St Albans (9 miles south-west), Bishop's Stortford (14 miles east), Welwyn Garden City (4 miles south) and Harpenden (8 miles west).
Local landmarks in Woolmer Green
Typical jobs here are in premises near Danesbury Park and The North Star pub and the streets around them. The nearest railway station is Knebworth station, roughly 1 mile north. A little further out are Datchworth Museum (1 mile east) and Queen Elizabeth II Hospital (4.8 miles south). Open spaces near Woolmer Green include Mardley Heath.
What we do, step by step
We turn up at the time agreed with you, often in the evening, overnight or at the weekend so the site keeps working. Equipment that has to be off is switched off and allowed to cool before any work starts, and the area around the work is covered and protected. On site, it takes a single shift for a typical unit, longer for large or heavily soiled ones. Photos of the system and how to reach it help us plan a visit to Woolmer Green.
- We agree a shutdown window that suits the building.
- We take before photos of each section of the unit.
- Filters, coils and internal surfaces are cleaned from intake to discharge.
- The fan and drain tray are cleaned and the drain checked.
- After pictures are taken and the certificate issued.
How to prepare
- Let us know when the site is closed or quiet
- Find the previous report, if there is one
- Make sure equipment near the work can be switched off and left to cool
Get a fixed quote
Quotes are quick. Call or email with a few details and you will usually have a fixed price within one working day. If we need to see the system first, we book a survey around your hours.
Advice
Also near Woolmer Green
More services for Woolmer Green
Common questions in Woolmer Green
Can ventilation in schools around Woolmer Green be cleaned out of term?
Yes, and it’s the easiest time to do it. There are about 5 schools, colleges and universities on the FSA’s food hygiene register within about 1.5 miles of Woolmer Green. Just call us on 0345 646 2711 or use the quote form with your term dates and we’ll plan around them.
Do you work at weekends in Woolmer Green?
Yes, out-of-hours work is a big part of what we do. Your customers, staff or residents in Woolmer Green needn’t be disturbed. Your opening times are the first thing we ask for.
What about areas you cannot get to?
The report shows them clearly. In ductwork, new access panels are often the answer, and we can fit those.
Do you cover Woolmer Green?
Yes. Woolmer Green is part of the area we cover, as part of our area across London and the South East.
Do you give a certificate after the clean?
Yes, both a certificate and a report with pictures. The report also suggests when the unit should next be inspected.
What do you do with what you remove?
It’s contained and taken away. We collect grease, debris and waste water as we go rather than letting it spread.
What is TR19?
TR19® is the BESA specification for keeping ventilation systems clean. TR19® Grease, a standalone specification since 2019, covers grease in kitchen extract systems, while TR19® Air covers other supply and extract ductwork.
Do you work with multi-site operators?
Yes. You deal with one contact for every site in our area, and visits can be set on a regular cycle.
What happens if it’s left?
Cleaning a unit while it only has light dust is quick. Leave it for years and dirt bakes onto coils and casings, especially where there’s been moisture. Out of sight is the usual reason a rural system goes too long without attention.
What you pay depends on how big the system is, what state it’s in and how easy it is to reach. We give you a fixed price before any work starts, so you know where you stand.
Why book with us
- BESCA Vent Hygiene Elite member, cleaning to BESA TR19® Grease
- Fully insured
- A single point of contact for sites across the South East and London
- Ventilation hygiene specialists since 2009
Read what affects the cost or our accreditations and certificates.
Keeping the system healthy
Here’s the after-treatment advice, in brief:
- Look at the condensate drain whenever the unit is serviced
- Plan the next inspection before the last report gets filed away
- Keep inspection doors on the unit in good order
- Don’t ignore odours coming through the grilles
We recommend when the unit should next be inspected or cleaned, based on what we found. Under TR19® Air the timing is set by inspection and risk, not a fixed calendar.
Keep the unit’s doors and panels in working order. Sections that are awkward to open are the ones that get skipped.
In-house cleaning or a specialist?
For ventilation and air handling systems, in-house care is mostly about checks: clear grilles, a log of filter changes and reporting anything odd. Cleaning inside ducts and units is specialist work.
In-house cleaning and specialist cleaning do different jobs. A daily filter wipe and a weekly filter wash keep grease down at the front of the system, but grease that has passed the filters is out of reach. Reaching it takes a specialist with the right equipment.
When it’s something else
To be straight with you, there are a few things this work won’t fix:
- Breakdowns that need a mechanical engineer
- Ductwork downstream of the unit, which is a separate clean
- Damaged coils beyond cleaning
If in doubt, give us a ring on 0345 646 2711 or send us an email and we will say what we think.
Parts of the system we cover
- Heating and cooling coils
- Dampers and louvres
- Internal panels
- Drain trays
- Filter sections
- Supply and extract fans
When to call us in Woolmer Green
An overdue filter loads up with dirt, cutting airflow and sometimes letting dirty air bypass them altogether. After that, the coils and fan collect what the filter should have caught.
Clients normally contact us after spotting one of these:
- Drain trays holding standing water
- Air handling units never cleaned inside
- Dirty fans and fan housings
- Filters that are clogged or overdue
Healthcare buildings such as Queen Elizabeth II Hospital, about 4.8 miles south, depend on their ventilation; if you manage a surgery, clinic or care home near Woolmer Green, yours matters too.
Before you book anyone
- Proof of accreditation you can verify
- Whether inaccessible sections are listed on the report
- Exactly which parts of the system are covered
- Whether a survey comes first