Cooking smells that are welcome inside a restaurant can be a nuisance to the flats above or the offices next door. Many kitchens, especially in towns and mixed-use buildings, have odour control equipment fitted to the extract. That equipment only works if it’s looked after. A clogged carbon filter or a dirty electrostatic unit can let smells straight through and put extra strain on the fan. This guide explains the common types and what maintenance they need.
Why odour control is fitted
There are two common reasons. The first is complaints. Neighbours who smell cooking all day may complain to the business or to the council. The second is planning. When a new kitchen or change of use is approved, the planning permission may include conditions about extraction and odour control, and those may require the equipment to be kept in working order. If you’re not sure, check your planning documents or ask the council.
Either way, the equipment is only as good as its last service. A unit that was fitted to satisfy the planners and then forgotten will soon stop doing its job, and the complaints usually follow.
Carbon filters
Activated carbon filters absorb odour molecules as air passes through. Over time the carbon becomes saturated and stops working. Grease reaching the carbon makes this happen much faster, which is why carbon filters are usually fitted after pre-filters and grease filtration.
Maintenance means checking pre-filters regularly, because a blocked pre-filter cuts airflow through the whole system, and changing the carbon at intervals that suit how much the kitchen cooks. A sure sign that the carbon is spent is that smells come back even though nothing else has changed.
UV units
Some systems use ultraviolet lamps in the canopy or duct to break down grease and odour. The lamps lose output over time and need replacing at intervals, and their housings and lamp surfaces need cleaning, because grease on the lamps blocks the light. UV units need to be isolated before work, as UV light can harm skin and eyes.
Need it done? Duct Doctor cleans and tests kitchen extract and ventilation systems across London and the South East, with a certificate and photo report after every clean. Get a fixed quote.
Electrostatic precipitators (ESP)
Electrostatic units charge particles of grease and smoke so they stick to collector plates. As the plates fill up, the unit becomes less effective, and heavily loaded cells can trip or arc. Cells need cleaning regularly, often by removing them and washing them, then checking they’re dry and reseated before the power goes back on.
Odour control and the wider system
Odour control units are part of the extract system, so they affect airflow and the fan. A blocked filter or loaded cell makes the fan work harder and can reduce extraction in the kitchen. Grease that bypasses filtration also ends up in the ductwork beyond, which is why the rest of the system still needs TR19® Grease cleaning at the right interval (BESA).
Duct Doctor offers odour control maintenance, including carbon filter changes and cleaning of UV and ESP units, which can be done on the same visit as a kitchen extract clean.
Keeping on top of it
- Keep a log of filter changes and unit cleans.
- Keep grease filters in the canopy clean, so less grease reaches the odour control unit.
- Take complaints seriously, and check the equipment when one comes in.
- Check any planning conditions and keep evidence that you’re meeting them.
See signs your extract needs cleaning for other warning signs.
Quick answers
How often should carbon filters be changed?
It depends on how much the kitchen cooks and how well grease is filtered first. Smells returning is the usual sign.
Can a dirty ESP unit stop working?
Yes. Loaded cells become less effective and can trip. Regular cleaning keeps them working.
Does odour control replace extract cleaning?
No. The ductwork, fan and discharge still need TR19 Grease cleaning.
Related services
More advice
- Signs Your Kitchen Extract Needs Cleaning
- Takeaway and Dark Kitchen Extract Cleaning
- Kitchen Extract Fan Problems and What They Mean
- Grease Filter Cleaning: How Often and How
- All advice
This guide is general information. It isn’t legal or insurance advice: check your own policy wording and lease, and speak to a qualified adviser about your fire risk assessment.