Cooker Hood Filters: Carbon, Charcoal and Grease Explained

Cooker hood filters are the part of the extractor most people ignore until the kitchen starts smelling of last week’s frying. There are two very different jobs happening inside that hood, done by two very different filters, and knowing which is which saves you money and keeps the fan working properly. One type you wash and reuse for years. The other you throw away and replace, and washing it does nothing at all. Here is how to tell them apart, look after each one, and work out which your hood actually needs.

The two types of cooker hood filter

Every extractor hood has a grease filter. Only some have a carbon filter. That single distinction is the source of most of the confusion.

Grease filters sit across the underside of the hood, facing the hob. Their job is to trap the greasy droplets thrown up by cooking so they do not coat the fan and ductwork. They are almost always a reusable metal mesh, either aluminium or stainless steel, and on bigger or pro-style hoods they take the form of stainless baffle plates. Because they only catch grease, they can be washed and put straight back, over and over, for the life of the hood.

Carbon filters, also called charcoal filters, do a completely different job: they absorb cooking smells from the air. They are packed with activated carbon and are fitted only to recirculating hoods, the type that filters the air and blows it back into the room rather than venting it outside. This is the filter people forget exists, and it is the one that has to be replaced rather than cleaned.

Do you even need a carbon filter?

This is the question worth answering first, because it decides half your maintenance. It comes down to how your hood is installed.

• A ducted (extracted) hood pushes the air outside through a pipe. The outdoors deals with the smell, so no carbon filter is needed. You only ever maintain the grease filter.
• A recirculating (ductless) hood cannot vent outside, so it relies on a carbon filter to scrub the smell out before the air returns to the kitchen. Without a working carbon filter, a recirculating hood removes grease and noise but does nothing about odours.

If you are still choosing a hood, our cooker hood buying guide explains ducted versus recirculating in full, because that choice affects far more than the filters. Ducted is more effective whenever an external wall or roof run is possible.

Cleaning grease filters

Metal grease filters are easy to look after and the single most useful thing you can do for your hood. Left clogged, they choke airflow, make the fan work harder and eventually let grease reach the motor.

Most aluminium and stainless mesh filters are dishwasher safe: pull them out, lay them flat in the machine and run a hot cycle. By hand, soak them in hot water with washing-up liquid or a spoon of soda crystals, scrub gently and dry before refitting. For everyday home cooking, once a month is a sensible rhythm; if you fry or wok-cook often, every couple of weeks keeps them from saturating. A telltale sign is when the mesh stops looking metallic and starts looking furred. Manufacturers such as Beko set out the same routine in their support guides.

One warning: aluminium can dull or discolour in a very hot dishwasher with harsh detergent. It is cosmetic and does not affect performance, but if it bothers you, wash those filters by hand.

Replacing carbon filters

Carbon filters cannot be cleaned. Washing them destroys the carbon or clogs it solid, and either way they stop absorbing smell. The activated carbon saturates invisibly over a few months, so you cannot judge a carbon filter by looking at it. That is why they are sold as replaceable consumables.

As a general rule, replace a carbon filter every three to six months with regular use, stretching towards nine to twelve months if you cook lightly. Heavy frying shortens that considerably. Always buy the filter specified for your exact hood model, as the shape and fitting vary between makes; the model number is usually on a plate inside the hood behind the grease filter. Some newer hoods have a saturation indicator light that tells you when the time has come, which takes the guesswork out of it.

A simple maintenance rhythm

Keep it easy and you will actually do it. Wash the metal grease filters monthly, or more often if you fry a lot. If you have a recirculating hood, diary a carbon filter change every three to six months. Wipe the hood canopy and controls at the same time so grease never builds into a sticky film. That is the whole routine, and it is the difference between a hood that clears steam and smells in seconds and one that grumbles along doing neither. If you are planning a wider kitchen refresh around your cooking zone, our cooker hood buying guide and range cooker buying guide cover what to fit and how to size it.

Frequently asked questions

What is the difference between a grease filter and a carbon filter? The grease filter is a reusable metal mesh that traps greasy droplets and is washed and refitted. The carbon (charcoal) filter absorbs cooking smells, is fitted only to recirculating hoods, and must be replaced rather than cleaned.

Can you wash a cooker hood carbon filter? No. Carbon filters are not washable. The activated carbon becomes saturated and washing it will not restore it, so a carbon filter has to be replaced, typically every three to six months.

How often should I clean my cooker hood grease filter? About once a month for normal home cooking, and every couple of weeks if you fry or cook at high heat often. Clean it sooner if the mesh looks furred or greasy, as a clogged filter strains the motor.

Does my cooker hood need a carbon filter? Only if it is a recirculating (ductless) hood that returns air to the room. Ducted hoods vent outside and never need a carbon filter, just the grease filter kept clean.

Are cooker hood grease filters dishwasher safe? Most aluminium and stainless steel mesh filters are dishwasher safe on a hot cycle. Aluminium can dull slightly in the dishwasher, which is cosmetic; wash those by hand in hot soapy water if you prefer to keep the shine.