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Your dehumidifier questions answered: from when you need one to which are best

Find out how to choose a dehumidifier, whether you can get away with buying a cheap one and more

Your dehumidifier questions answered: from when you need one to which are best

High levels of humidity in your home can lead to a build-up of damp, dust mites, mould and fungi, damage to your home and possessions and even health problems. The right dehumidifier can help. 

There are plenty of dehumidifiers that you could buy, but how do you make sure you’re buying a good one and not wasting your money?

I asked our senior researcher for air quality, Christina Woodger, all your burning questions on buying and using a dehumidifier.

Just want to know which dehumidifiers aced our tests? Head straight to our list of Best Buy dehumidifiers

How do you know if you need a dehumidifier?

If you’re noticing the following things in your home, you more than likely need a dehumidifier:

  • Stains on your ceilings or walls
  • Lots of condensation on your windows
  • Mould or mildew
  • A musty smell
  • Laundry taking ages to dry

If your damp problem is severe, crumbling skirting boards, peeling paint and wallpaper or floor coverings lifting up, for example, you might need to call in a professional. Our guide to dealing with damp can help.

Which is the best dehumidifier to buy?

Dehumidifiers fall into two camps: refrigerant and desiccant. Each uses slightly different technology to draw water from the air.

Refrigerant dehumidifiers are the most common type in the UK. They’re generally only effective in heated rooms; desiccants are often better than refrigerants for unheated garages or outbuildings. However, we have found some versatile models of both types that work well in a range of conditions.

At Which?, we’ve been testing dehumidifiers for years, checking how well they pull water from the air in warmer and cooler rooms, whether they’re easy or a faff to use, whether they use energy efficiently and whether they run nice and quietly or make such a racket that you won’t want to use them.

Arm yourself with all the information you need by reading our guide to buying the best dehumidifier.

How big a dehumidifier do you need?

You’ll often see dehumidifiers described by their capacity. Capacity doesn’t relate to its size, or how much it can hold in its tank (although dehumidifiers with larger capacities will often also be bigger, with correspondingly bigger tanks). Instead it describes a dehumidifier’s extraction rate – the amount of water it can pull from the air each day.

To complicate matters further, the claimed capacity is often based on conditions you’re unlikely to actually have in your home. For refrigerant dehumidifiers, manufacturers frequently base their claims on 30ºC and 80% relative humidity (ie tropical rainforest conditions). That’s because the higher the temperature and the higher the humidity level, the more effectively a refrigerant dehumidifier will work.

So, if a dehumidifier has a capacity of 20 litres, this doesn’t mean it will extract 20 litres of water a day from your home.

But, you can use capacity as a rough guide. The higher the capacity, the more water it will collect. If your home is large, and there are plenty of you having showers, boiling the kettle and so forth, you’ll need a model with a larger capacity (18 or 20 litres). Whereas if your living space is only tiny, and you live alone, a 10 litre model might do – a large one would be too noisy and take up more floor space than you’d want to relinquish.

Should you buy a Currys or Argos dehumidifier?

Both Argos and Currys stock a wide range of dehumidifiers from other brands, but also sell own-brand dehumidifiers.

Challenge (Argos) dehumidifiers start at £50 for a mini 0.5 litre dehumidifier and go up to £140 for a 12 litre dehumidifier.

The Challenge Mini Dehumidifier MD-818 is a tiny little thing (22cm height x 16cm width x 16cm depth) with a water tank about the size of a large glass of wine. Because it’s so small, it’s not really comparable to a full-sized dehumidifier in terms of its ability to dry out a room.

The other two Challenge models currently on sale are the Challenge 10L 849/9493 (£120; above) and the Challenge 12L 820/9449 (£140) – both refrigerant models.

They can both be set up for continuous drainage into a drain hose outlet, such as a sink or floor drain, via a water tube. You’ll have to buy the tube separately, but garden hose will do for most dehumidifiers. This could save you having to keep emptying the tank.

They’re both easy to move around, if you need to dehumidify several parts of your home. Neither has wheels, but both come with a carry handle.

Find out what we thought of them of the Challenge 10L 849/9493 and the Challenge 12L 820/9449 by reading our full reviews.

Like the Challenge models above, Logik (Currys) own-brand dehumidifiers are fairly cheap. We recently tested the Logik LD20DH19 (£130; above), which is another refrigerant. This one has a larger capacity (20 litres), meaning it’s suitable for a larger home. Again, it can be set up to drain continuously, but this one comes with a hose. And it has castors for rolling across the floor.

Our full Logik L20DH19 review reveals whether it’s easy to use in other respects and, crucially, whether it will do a good job of drying out the air in your home.

Can you buy a good cheap dehumidifier?

Dehumidifiers vary wildly in price – you could spend as little as £50 or as much as £350.

You’ll need to spend at least £130 for a Best Buy dehumidifier. There’s no need to pay through the nose, though. Some of the most expensive ones we’ve tested haven’t especially impressed us.

Cheaper dehumidifiers have often tended to be smaller, and with fewer features – which is fine if you only have a small home to dehumidify, there aren’t many people living in your home, and you’re not looking for anything particularly sophisticated.

This isn’t universally true, though. For example, the Inventor EVA II Pro Wi-Fi dehumidifier (£159; pictured above), which we tested recently, has a large claimed capacity of 20 litres, has an ioniser, designed to freshen up musty rooms, and can be controlled from a smartphone app.

If your damp problem is very mild (you’ve just got a touch of condensation on your windows, for example), you might be able to get away with a damp trap, aka a moisture absorber. They contain crystals, which draw in moisture.

These are very cheap (£1-10) but you will need to buy replacement crystals every month or so. And they’re definitely not designed for serious damp problems.

How do you get rid of an old dehumidifier?

If your dehumidifier no longer works, and you want to get rid of it, don’t put it out with the rest of your household rubbish.

UK households dispose of more than 1.2 million tonnes of electrical waste each year – enough to fill Wembley Stadium six times over. Much of this ends up in landfill sites.

You should recycle your old electrical products wherever possible to avoid this.

Recycle Now, the national recycling campaign for England, says that there’s an easy way to tell if your electrical item is recyclable. If the answer is yes to one of the following questions:

  • does it have a plug?
  • does it use batteries?
  • does it need charging?
  • does it have a picture of a crossed-out wheelie bin on it?

then it is recyclable. All dehumidifiers use plugs, so all they all fall into this category.

The WEEE (Waste Electrical and Electronic Equipment) scheme is compulsory for all electrical retailers in Britain.

You can take your old dehumidifier to your local household waste recycling centre, back to any retailer selling dehumidifiers, or directly back to the manufacturer. The manufacturer will then break the dehumidifier down and send the individual components off for recycling.

Changes are planned to the WEEE scheme in the near future, though. We’ll update this story once we know more.

If it’s simply a case that you no longer need your dehumidifier, and you’re confident that it’s in good working order (see the next question), you could donate it to a friend in need, sell it or freecycle it via a site like Trash Nothing.

Be considerate and clean it first. Make sure the tank is empty, remove any debris from the collection tray, clean the air filter (following the manufacturer instructions) and wipe down the outside with a cloth.

Can you buy a used dehumidifier?

No one really wants to spend money on a dehumidifier.

There are plenty of cheap second-hand dehumidifiers on sale on sites like Amazon, eBay and Gumtree. It’s a case of ‘buyer beware’, though, as you won’t know for certain that it’s in good working order. It’s worth paying extra for a new one for peace of mind, if you can.

If you’re going to buy a second-hand dehumidifier, try to find out as much as possible about it before parting with your money.

In an ideal world, you would want to buy locally and see the machine running and collecting some water before agreeing to buy it.

If you’re buying online, check the returns policy of the site you’re buying it from.

Use Electrical Safety First’s online product recall checker to make sure the dehumidifier isn’t subject to a recall.

Make sure you get a copy of the instruction leaflet (you might be able to find this online).

Check it’s still under warranty, but be aware that the manufacturer may not be able to honour it. Popular dehumidifier manufacturer Meaco told us that if someone can prove that their dehumidifier came from a family member or friend, then they will transfer the warranty. But they, and many other dehumidifier manufacturers, can’t always honour the warranty on a second-hand electrical appliance, because they don’t know its history.

Before you use it for the first time, inspect it for any signs of damage, including cracks in the water tank and damage to the cord or plug. If in any doubt at all, don’t use it.

Find out more about your rights when buying second-hand goods. Or head straight to our dehumidifier reviews to see which are the best and worst.

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