How Often You Actually Need to Clean Your Range Hood Filter

I have a slightly embarrassing confession. For the first six years that I lived in our current house, I did not realise the range hood above the cooker had a filter. I had assumed it was decorative metal, or perhaps a vent cover. I knew it caught grease, but I had never thought of it as a thing that could be removed and cleaned. I had certainly never thought of it as a thing that needed to be cleaned.

I was wrong on every count. The metal grille at the underside of nearly every range hood is a mesh filter that traps grease before it can build up inside the ducting and the fan. When the filter is clean, the hood pulls cooking fumes away efficiently and quietly. When it is clogged with months of accumulated grease, the hood becomes noisy, ineffective, and a genuine fire risk.

How often, honestly

For a household that cooks most nights, every six to eight weeks. For occasional cookers, every three months. For anyone who does a lot of frying, deep-frying, or wok cooking, every three to four weeks.

The visual test is simpler than any rule: look up at the filter. If it is sticky to the touch, it is overdue. If you can see brown discolouration through the metal, it is well past time. If you can feel grease on it when you swipe a dry finger across, that is the upper limit.

The manufacturer’s manual will often suggest cleaning every month. This is conservative but reasonable for kitchens with heavy daily cooking. For most domestic kitchens, six to eight weeks is enough.

The cleaning method that actually works

Most range hood filters are made of aluminium mesh, which can be cleaned in three ways. In ascending order of effort and effectiveness:

Dishwasher

Many filters fit in the top rack of a dishwasher. Run on the hottest cycle with a normal tablet. This works for light grease but struggles with months of accumulation, and over time can dull the appearance of the aluminium.

Hot water and washing-up liquid

Fill the sink with the hottest tap water you can manage, add a generous squirt of washing-up liquid, and add half a cup of bicarbonate of soda. The bicarbonate makes a noticeable difference; it helps emulsify the grease that washing-up liquid alone struggles with. Drop the filters in. Soak for 30 minutes. Scrub with a non-scratch sponge. Rinse with hot water. Let air-dry.

Boiling water with soda crystals

For badly neglected filters (and I write from personal experience), the only method that fully works. Lay the filters in a large baking tray. Pour over a kettle of boiling water mixed with three or four tablespoons of soda crystals (washing soda, not bicarbonate). Let sit for 15 minutes. The grease will visibly dissolve. Scrub gently. Rinse. The first time I did this, I scrubbed off what looked like a year of solid grease in twenty minutes.

Wear gloves. Soda crystals are quite alkaline and unpleasant on the skin.

The often-forgotten second filter

Many range hoods have a second filter beyond the visible mesh: a charcoal filter that absorbs cooking odours. This is found in recirculating hoods (those that vent back into the kitchen rather than to the outside). Charcoal filters cannot be washed; they have a finite life and need replacing every six to twelve months depending on cooking habits.

If your kitchen has started to smell of last night’s dinner the morning after, the charcoal filter has probably reached the end of its usable life. Replacement filters cost between ten and forty pounds and are usually a slot-in part requiring no tools.

If you are unsure whether your hood vents outside or recirculates, look at the ducting above the hood. A duct that runs to an exterior vent means you do not need a charcoal filter at all. A duct that loops back into the kitchen, or no duct at all, means you do.

What lives in the fan housing

Beyond the filter, grease that escapes the filter ends up inside the fan housing. Once a year, take the filter out and look up into the housing. You may find a layer of brown grease on the blades and the inside of the housing. This is the kind of build-up that can ignite during a kitchen fire on the cooktop below.

With the hood unplugged or the kitchen breaker off, wipe down the inside of the housing with a degreasing cleaner (any kitchen degreaser, or hot water with washing soda) and a microfibre cloth. Do not run a wet cloth into the motor or the wiring. The cleaning is awkward because you are reaching up over your head, but it takes about fifteen minutes for a year of grease.

Why the bulbs almost always fail too early

Most range hoods have one or two lights underneath. These almost always fail before the rest of the hood does, partly because they sit in a hot, greasy environment. Replacement is usually a screw-in or twist-in change, takes thirty seconds, and the bulbs are inexpensive.

If the lights flicker or fail to turn on, the issue is usually the bulb, occasionally the switch, very occasionally the wiring. Try a new bulb first. If that fails, the switch may be sticky from grease and benefits from a careful wipe with a damp cloth (with the breaker off).

The bigger picture: ducted versus recirculating

If you are considering a new range hood, or installing one for the first time, ducted to the outside is significantly more effective than recirculating. Recirculating hoods filter air but do not remove moisture or grease from the room. Over years, that moisture and grease ends up on the ceiling, the upper cabinets, and the walls.

If a ducted installation is genuinely impossible (some flats and conversions), use the most powerful recirculating hood you can find, change the charcoal filter conscientiously, and accept that you will need to clean upper kitchen surfaces more often than you would in a ducted setup.

The small habit that matters most

Turn the hood on before you start cooking, not after the fumes have already filled the kitchen. Leave it running for two or three minutes after you finish to clear the residual moisture and grease. This single habit captures roughly twice as much grease as turning the hood on after smoke has already appeared.

It is one of those quietly effective things that nobody tells you when you move into a kitchen with a hood. It is also one of the easiest to adopt; the hood is right there, the switch is just over the cooker.

For the broader rhythm of small kitchen and appliance maintenance, our Sunday routine includes the filter check as part of the regular cycle.

For a related angle, our piece on How to Diagnose a Loud Washing Machine Without Calling Anyone covers a closely connected problem.