The Hood That Only Hums: Is Your Kitchen Extractor Doing Anything at All?

There is a particular kind of comfort in switching on the cooker hood. It rumbles into life, the kitchen feels a bit more professional, and you get on with the onions. But in a British winter, when the windows stay shut and the kettle is never far away, that reassuring hum can be misleading. A hood can make all the right noises while doing very little about the steam, grease and cooking smells that build up in the room.

That matters more than many of us realise. Kitchens produce a surprising amount of moisture — boiling pasta, simmering stews, steaming vegetables, even a long hot wash-up. In a sealed-up house, that moisture has to go somewhere. Often it ends up on the windows, in the corners, or behind the tiles. A working extractor is one of the simplest ways to give it a way out.

First, work out what kind of hood you have

Not every cooker hood is an extractor. Broadly speaking, there are two types.

Ducted hoods pull air from above the hob and send it outside through a duct. That is true extraction. The moisture, smells and grease particles leave the building.

Recirculating hoods pull air through a filter and then push it back into the kitchen. They can trap some grease and reduce odours, but they do not remove moisture. The steam from your Sunday roast is still in the room. If your home has no external wall nearby, or the duct route was never installed, you may well have a recirculating model without realising it.

A quick clue: look above the hood. If you can see a rigid or flexible duct heading towards a wall or ceiling, it is probably ducted. If the hood sits flat against the wall or under a cupboard with no obvious route out, it may be recirculating. The manual or model number will confirm it.

The signs that your hood is mostly decorative

A hood that is not extracting properly rarely fails dramatically. It just becomes part of the background. Watch for these clues:

• Steam hangs around after cooking, especially on nearby windows or the wall behind the hob.
• Smells linger for hours, even when the hood has been running throughout.
• A faint greasy film appears on surfaces near the cooker.
• The hood is noisy, but a piece of kitchen roll held near the grille is barely pulled towards it.
• The external flap — if you can see one — does not move when the fan is on.
• Condensation forms on the window while you are cooking, then clears slowly afterwards.

None of these prove the hood is broken. But together they suggest it is worth a closer look.

Four checks you can do yourself

Before you book a visit, a few simple checks can rule out the most common problems. Switch off the hood at the wall first, and give it time to stop.

1. Check the filter

Ducted hoods usually have metal mesh filters. These catch grease and can be washed in hot soapy water — check the manufacturer's instructions. A clogged mesh filter restricts airflow and makes the motor work harder. Recirculating hoods often use a charcoal or carbon filter, which cannot be washed and needs replacing every few months depending on use. If you have been running a recirculating hood with an exhausted charcoal filter, it is doing even less than you think.

2. Look at the outside vent

If your hood is ducted, find the external terminal. It might be on a wall, under a soffit or through the roof. With the hood running, check whether air is coming out and whether the flap opens. Sometimes the flap is stuck, painted shut, blocked by a bird's nest or simply facing the wrong way in the wind. Do not poke around on a ladder in bad weather — a mirror or a phone camera from a safe position may be enough for a first look.

3. Follow the duct route if you can

Long, twisting runs of flexible corrugated duct are notorious for killing airflow. Every bend and every metre of unnecessary pipe adds resistance. If the duct has come loose behind a cupboard, or was never connected properly in the first place, the hood may be blowing air into a void rather than outside. Access panels and cupboard backs can sometimes reveal the truth.

4. Give the fan blades and grille a wipe

Grease builds up quietly. A sticky grille and dirty blades reduce performance and can make the hood sound rougher than it should. A gentle degrease with a suitable cleaner — again, after isolating the power — can make a noticeable difference.

Why this matters more in the closed-window season

In summer, an open window does a lot of quiet work. In winter, most of us keep them shut. Modern UK homes are also much more airtight than older ones, which is good for heat retention but means moisture and cooking fumes have fewer escape routes.

When a kitchen hood is not extracting, that moisture spreads. It can condense on cold glass, settle into window reveals and make the kitchen feel clammy. Over time, repeated dampness can encourage mould on walls and sealant. Better kitchen ventilation does not solve every condensation problem in a home, but it takes pressure off the rest of the house at the point where a lot of moisture is created.

If you have a recirculating hood

Recirculating hoods are not useless. A clean, well-fitted model can reduce grease and some odours, and they are often the only practical option in flats or internal kitchens. But be realistic: they are not removing moisture. Use pan lids, run the hood while cooking, and consider short bursts of background ventilation if you have trickle vents or a window that can be opened safely. A simple hygrometer can help you see how quickly the kitchen humidity climbs.

When to call someone in

If you have cleaned the filter, checked the outside flap and still get weak airflow, the problem may be deeper: a disconnected duct, an undersized motor, a blocked route or an installation that never worked properly. That is the point to bring in a professional. The same applies if the ducting is inaccessible, if the hood is under warranty, or if you rent and are not sure what you are allowed to touch.

A cooker hood is not the most glamorous piece of kit in the home, but in winter it earns its keep. The test is simple: is it moving air, or just making a noise? Once you know which, you can decide what to do next — and your windows, walls and lungs will thank you for it.