Duct Doctor · London and the South East
Grease filter exchange
Dirty canopy grease filters swapped for clean ones on a regular schedule, so the first line of defence in your extract keeps working.
- Filters clogged with grease
- Staff losing time scrubbing filters
- Filters soaked in the sink and still greasy
What grease filter exchange involves
Grease filters sit in the canopy and catch a share of the fat in cooking vapour before it reaches the duct. They only work when they’re clean. A clogged filter slows the airflow, so the kitchen gets hotter and smokier, and grease that would have been caught carries on into the plenum and ductwork. Cleaning filters by hand in the pot wash takes time, and it rarely gets them properly clean. Our grease filter exchange takes the job away. On each visit we take out the dirty filters and fit clean ones, at a frequency that suits how hard your kitchen cooks. The dirty filters are taken away and cleaned. We check that each filter fits properly with no gaps, and we flag damaged ones so they can be replaced. It doesn’t replace a full TR19® Grease clean, but it helps keep the system cleaner in between. Our grease filter cleaning guide has more.
We cover London and the South East, and have done since 2009. We’re a BESCA Vent Hygiene Elite member, cleaning to BESA TR19® Grease, we hold CHAS, SafeContractor and ISO 9001, and we’re fully insured.
Problems we put right
- Filters clogged with grease
- Staff losing time scrubbing filters
- Filters soaked in the sink and still greasy
- Damaged or missing filters leaving gaps
- Grease getting past the filters into the duct
What we work on
- Baffle filters
- Mesh filters
- Wall canopies
- Island canopies
- Restaurants and pubs
- School and hospital kitchens

How it works
- We count and measure your filters and agree a visit frequency that suits your cooking.
- On each visit the dirty filters come out and clean ones go in.
- We check every filter fits properly, the right way round, with no gaps.
- Damaged or poorly fitting filters are flagged so they can be replaced.
- The dirty filters are taken away for cleaning, ready for the next swap.
Why clean filters matter
Baffle filters work by making the air change direction so the grease drops out. Clogged with fat, they can’t do that, and they choke the airflow too. A missing or damaged filter is worse, because it leaves a gap for grease to pass straight into the duct. Keeping a full set of clean, well-fitted filters in the canopy is one of the simplest things a kitchen can do.
Filters and TR19
Filters are part of the system TR19® Grease covers, and they’re cleaned on every full clean. A filter exchange keeps them working between cleans. It doesn’t clean the plenum, the duct or the fan, so you’ll still need full cleans at the frequency BESA sets for your hours of cooking. What it does do is slow down how fast grease reaches the duct, which helps the system stay in better shape between those cleans.
Why it’s worth doing now
Clogged filters slow your extract, make the kitchen hotter and let more grease into the duct, which means the duct fouls faster between cleans. Scrubbing filters by hand takes staff away from food and rarely gets them clean. If your filters are dark, sticky or damaged, or nobody is quite sure when they were last done, a regular exchange fixes that and keeps the canopy looking right for EHO visits. It also gives you a simple record that the filters are being looked after.
What affects the quote
We don’t publish set prices, because no two systems are the same. Send us a few details and photos, or book a survey, and we’ll give you a fixed price before any work starts. The main things that change it are:
- The size of the system: number of canopies, length of ductwork, risers and fans
- How much grease or dirt has built up since the last clean
- Access: roof-level fans, ceiling voids, risers and how many access panels there are
- When the work can happen: overnight, weekends or school holidays
- Whether extras are needed, such as new access panels, filter exchange or damper testing
- How many sites you want covered on one schedule
What a good quote includes
- A survey or clear photos before the price is given
- Exactly which parts of the system will be cleaned or tested
- How areas that can't be reached will be recorded
- A certificate or written report with before-and-after photos
- Proof of insurance and accreditations you can check
- The recommended date for the next visit
Afterwards
Clean filters are fitted on every visit, and we flag any that need replacing. Between visits, make sure filters stay in place and the right way round, and don’t run the canopy with gaps. Wipe the canopy down daily. If your menu or hours change, tell us so we can adjust the visit frequency. Keep booking your full TR19 cleans as usual; the exchange makes each one easier.
Grease filter exchange: common questions
How often should grease filters be changed?
It depends on how many hours a day you cook and what you cook. Busy kitchens with fryers and grills need more frequent swaps. We’ll suggest a frequency and adjust it once we see how quickly they foul.
Does a filter exchange mean we don’t need TR19 cleaning?
No. Filters are only the first stage. The plenum, ductwork and fan still need cleaning at the frequency BESA sets.
What if our filters are damaged?
We flag damaged or poorly fitting filters so they can be replaced. Gaps let grease straight into the duct.
Can we keep cleaning some filters ourselves?
Yes. Some kitchens use the exchange for the busiest canopies and clean others in-house. We’ll fit around how you work.
Do you need to come when the kitchen is closed?
Filters can only be swapped when the equipment below is off. We agree a visit time that fits around your service.
Do you give a fixed price before you start?
Yes. Send a few details and photos, or book a survey, and we’ll give you a fixed quote, usually within one working day.
Do you work out of hours?
Yes. We work evenings, overnight and at weekends so your kitchen or building doesn’t lose a day, and there’s a 24/7 line for emergencies.
Page updated 30 October 2026
Near you
We cover London and the South East. Find grease filter exchange in your town:
- London
- Brighton
- Southampton
- Portsmouth
- Reading
- Oxford
- Milton Keynes
- Guildford
- Chelmsford
- Maidstone
- Woking
- Crawley
- Croydon
- St Albans
- Canterbury
- Basingstoke
- Slough
- High Wycombe