Replacing a kitchen extractor fan: Can you use old ducts with a new unit?

We put our kitchen extractor fans through a lot. Or rather, we put a lot through them. Years of fan-powered fume extraction or purification wears out these appliances. As a result, kitchen extractors often need to be replaced within around 7-10 years.

There’s plenty to consider when replacing a kitchen extractor fan. You need to choose the right replacement extractor, safely uninstall the previous unit, and then install the new extractor – probably working with a kitchen layout that was designed around the previous kitchen appliance.

To help you get this right, we interviewed Harry Young, an extractor fan specialist and Director of ExtractorFanMan.co.uk, and Clive Holland, a DIY expert and presenter at Fix Radio. Read on for their advice on kitchen extractor replacement, from choosing the right new model to working with existing ducting and electrics.

Harry Young

As Director of ExtractorFanMan.co.uk, Harry Young installs and replaces kitchen extractors and cooker hoods in Southampton, Eastleigh and other parts of Hampshire. Young is also an experienced renovator and property developer.

Choosing the right kitchen extractor fan

Replacing a kitchen extractor is an opportunity to improve the appearance, condition and air quality of your kitchen. It pays to choose your replacement model carefully.

Harry Young, Director of ExtractorFanMan.co.uk, advises that it’s crucial to consider the new unit’s extraction rate.

“It is advisable to follow building regulation part f guidelines and install an extractor which meets these minimum levels, but above all I would suggest choosing an extractor that can provide you with at least 15 air changes an hour when extracting externally,” says Young.

“To calculate this, you need to work out the volume of air in your kitchen. For example, a 3m by 3m kitchen with a ceiling height of 2.4m would be calculated as 3 x 3 x 2.4 = 21.6m3 of air volume.

“Multiply this by 15 changes an hour = 324m3/h, meaning you would want to choose an extractor that has this level of extraction as a minimum,” he says.

Filter maintenance and energy efficiency are also important factors to consider.

“Charcoal filters in recirculating models need replacing every few months, while grease filters in vented extractors should be washed regularly,” says Clive Holland, a DIY expert and Fix Radio presenter.

“Also, if you’re keen on a sleek and modern look, integrated or downdraft extractors can be a good choice, but they are often more expensive,” he adds.

Clive Holland

Clive Holland is the former host of Cowboy Trap on the BBC. Now a broadcaster on Fix Radio, the UK’s only national radio station for builders and tradespeople, Holland is one of the UK’s leading property and DIY experts.

Recirculating vs vented: Is it easy to switch?

If you have been using your current extractor as a recirculating cooker hood, then you might consider switching to a vented system that extracts air from the building.

“The choice largely depends on your kitchen layout and personal preferences,” says Holland.

“A vented extractor which removes air directly outside is a good option for eliminating cooking odours and excess moisture. They help prevent condensation and grease build-up, which is ideal for busy kitchens where lots of frying and boiling take place. However, vented extractors require ducting, which can be tricky to install if your kitchen isn't positioned near an external wall,” he says.

Meanwhile, Holland recommends the use of recirculating cooker hoods in properties where adding ducting and a vent would be impractical.

“These models use filters to clean the air before releasing it back into the kitchen, making them easier to install and more flexible in terms of placement. They are useful for flats or kitchen islands where running a duct isn’t an option. However, they do require regular filter changes to stay effective, and they may not be as efficient at removing heat and steam as vented options,” he says.

Many of the best kitchen extractor fans can be used as either a recirculating or vented unit, depending on how you configure them.

How to ensure a new kitchen extractor will fit where an old one was installed

Young stresses the importance of choosing an extractor with parts that are suitably sized and shaped for the room.

“You may have existing ducting or an electrical connection that was in the chimney part of the old extractor – and if your new extractor has a chimney with different dimensions, these parts may be visible or in the way of fixing the new chimney, which can pose problems during installation,” he says.

The same type of problem could apply to both canopy and integrated kitchen extractors.

“The cut-out made in the kitchen unit accommodating the previous extractor may be too big or small for the new extractor, meaning alterations and adaptations would need to be made, ” says Young.

“Another point to consider is the minimum distance an extractor can be above a hob. Remember that the gap between the extractor and an electric hob must be at least 650mm, increasing to 750mm when above a gas hob.”

Try these stylish kitchen extractor fans to replace your old one

How to replace a kitchen extractor fan

Before you start any work on replacing a kitchen extractor fan, you must ensure the power to the extractor is isolated and switched off. If electrical alterations are required, get help from a qualified person such as an electrician or appliance technician.

1. Mitigate for potential damage to the kitchen

“Before attempting to uninstall a kitchen extractor, ensure that power to the extractor is isolated and switched off,” says Young.

“You should then cut away any silicone or sealant that has been applied around the edge of the extractor. Not doing this can lead to paint and plaster being pulled from the wall.

“Equally, if you have a tiled splashback, check if this goes behind the extractor, because if the tiles have been installed subsequently to the extractor, you run the risk of pulling tiles from the wall when uninstalling,” he adds.

2. Remove the old extractor unit

Uninstalling the old extractor should be relatively simple. You’ll need to unfasten the screws that secured the unit to the wall, and then lift the unit down (probably with help from another person). According to Young, it’s important to handle components carefully.

“Often the electrical connection can be located within the chimney part, so take care to avoid pulling on any wires or electrical connections,” he says.

“When uninstalling a ducted extractor, it is very easy to rip the ducting or pull it out of place. If you pull it out of place and the ducting disappears into a wall, you might have a job trying to find where it has come loose!”

3. Assess existing system components

Sometimes, you can save money and effort by reusing parts used with your old extractor – especially the duct and vent in a ducted system. However, this depends on the condition of the components.

“If you have existing ducting for extracting externally, it is wise to look inside and check if there is a significant amount of grease build up or rips and tears, and that the ducting is not misshapen,” says Young.

“Any significant deformations can reduce the airflow from your new extractor, making it work harder and ultimately reducing its lifespan. Rips in the ducting could lead to hot steamy air being released into somewhere like the wall cavity, which can lead to problems like damp.”

Before reusing existing ducting, you’ll also need to check whether it meets your new extractor’s specifications.

“Check what size ducting is recommended by the extractor’s manufacturer as this could affect any warranty – it usually ranges from 100mm to 150mm circular ducting,” says Young.

You’ll most likely be able to use the same electrical connection that powered your previous extractor with the new unit, but it’s essential to check the new model’s requirements before you connect it.

“In some cases you may need to alter the electrical outlet and install a fused connection, single socket outlet, or other type,” says Young.

“Additionally, you will need to ensure the supply you have is rated properly for the new extractor. If you do attempt any electrical work, ensure the power supply is isolated and switched off first.”

4. Install the new extractor unit

If you want detailed guidance on this step, see our guide to installing a kitchen extractor.

In short, you will need to isolate and switch off power to the relevant electrical outlet, assemble the extractor, mount it on the wall, and then either install its filters (for a recirculating model) or connect the ducting leading out of the building (for vented models).

“Take your time and be careful of hidden cables and pipework when drilling through, as kitchens can be high traffic areas for services running behind the wall,” says Young.

With ducted extractors, creating a tight connection between the extractor and the duct is crucial.

“A common pitfall is the use of incorrect ducting connectors and inadequate tape to seal the connections,” Young adds.

“Do not be tempted to use a piece of old pipe to provide a connection, as specifically made connectors (like this 100mm model) are available at very low prices and will give you better longevity. We use foil insulation tape combined with jubilee clips to ensure our connections do not come loose.”

FAQs

Is it better to get a professional to replace your kitchen extractor?

Some confident DIYers do replace their own kitchen extractor, although the complexity of the task depends greatly on the type of installation. For example, replacing one recirculating cooker hood with another is relatively straightforward, whereas adding ducting and a vent to create a new vented extraction system would be far more challenging.

“Although removing, replacing and installing an extractor fan can seem like a simple DIY task there are many pitfalls, from selection of an appropriate extractor to installation,” says Young.

“We would recommend contacting a professional to aid in replacing or installing a kitchen extractor. They may be able to give suggestions to help you improve your extraction system and will have all the various tools and sundries required to complete an effective kitchen extractor installation.”

What can go wrong when replacing a kitchen extractor fan?

According to Holland, one of the most common errors encountered during kitchen extractor fan replacement is choosing an extractor that’s not the right size for the hob.

“A unit that’s too small won’t effectively capture steam and grease, meaning your kitchen could still end up feeling hot and sticky after cooking,” he says.

“Check the extraction rate and make sure it matches your kitchen size, as bigger spaces need stronger airflow. You should also consider noise levels, especially if your kitchen is open-plan. A quieter model will make a huge difference when you’re having a conversation while cooking.”

Another pitfall to watch out for is selecting a low-quality or high-maintenance extractor.

“Don’t always go for the cheapest option just to save money, because a poor-quality extractor won’t last long and may struggle to do the job properly,” says Holland.

“Think about maintenance too – some models need more frequent filter changes than others, which can add to their long-term costs.”

Upgrading your kitchen extractor fan is one of the best things you can do for the air quality in your home. A good recirculating model will remove unhygienic particulates from cooking fumes, leaving you with cleaner air, while vented models remove stovetop fumes entirely. For more ideas to help you breathe cleaner air at home, see our guides on positive input ventilation (PIV) and air purifiers.