Living in a damp, mouldy property increases your chances of developing breathing problems, allergies and asthma, and can affect your immune system. A dehumidifier can help you keep excess moisture in check.
Many of us are spending almost all our time at home at the moment, so it’s more important than ever to think about indoor air quality.
Living in a damp environment can be harmful to your health in a number of ways, with children, elderly people, people with respiratory conditions, people with skin conditions and people with a weakened immune system at most risk, according to the NHS.
As well as affecting your health, damp can cause serious damage to your property, which will get ever more costly to repair the worse it gets.
Read on for five tips on tackling damp problems with a dehumidifier, and discover the latest models we’ve tested from Ecair, Inventor and Meaco.
1) Gauge the level (and cause) of your damp problem
Minor damp problems
Not every damp problem needs expensive solutions. For example, you may be able to tackle a touch of condensation on your window panes with a moisture absorber. These are cheap little things (often around £5) that sit on your window sill and contain crystals that absorb moisture.
Moderate damp problems
If you’ve tried a moisture absorber, but find you’re constantly emptying out the water it collects and topping up the crystals, it’s a good indication that you need the higher extraction power of a dehumidifier. Other signs of damp that would benefit from a dehumidifier include:
- Stains on your walls and ceilings
- Mould and mildew
- Persistent musty smells
- Laundry taking forever to dry
- Walls feeling very cold or damp
- Windows regularly streaming with condensation.
Serious damp problems
If your damp problem is severe – you’re noticing damaged skirting boards or plaster, floor coverings lifting up, or wet and leaking walls, for example – then a dehumidifier alone won’t be enough.
You’ll need to call in a professional before damp causes further damage to your home. They can help you identify what’s behind the damp so that the problem can be tackled at the source.
It might be something that’s easily remedied by a few simple lifestyle switches, or you might have a bigger structural problem on hour hands. Either way, the sooner you take action, the better.
Which? Trusted Traders can help you find a good damp proofing specialist that’s passed our rigorous assessment processes. 
How damp is your home?
Not all signs of damp are immediately obvious. If you suspect damp, but can’t spot any significant physical signs, you could try buying a hygrometer (humidity meter). These are pretty cheap – often less than £10 – and will give you an idea of how humid the air in your home is.
The table, below, gives an indication of ideal, too dry, and too humid levels.
| Relative humidity (RH) | Impact |
| Below 30% | Too dry – can lead to dry skin and dry nasal passages – increasing your vulnerability to respiratory illnesses |
| Between 30% and 60% | Good range of indoor humidity in cooler months |
| Above 60% | Dust mites reproduce faster |
| Above 68% for long periods of time | Mould is likely to grow |
Diagnose your damp problem: check out our guide to dealing with damp.
2) Pick the right type of dehumidifier
Dehumidifiers use one of two types of technology to dry out the air; each is suitable for different environments.
Refrigerant dehumidifiers (also called compressor dehumidifiers) are generally only suitable for warmer environments: typical, occupied homes which are heated when the weather gets chilly. We have found a couple of refrigerants that also work well in colder temperatures, but they’re very much the exception.
Desiccant dehumidifiers work well in both warm and cooler environments, so are the better choice if you want a dehumidifier for a garage, conservatory, caravan or boat, or if you want one that you can use in a range of conditions. They give out more heat than refrigerants, though, which you might not necessarily want if your home is already heated.
There are more refrigerants on the market, so you’ll have more choice if you’re looking for a refrigerant.
Our dehumidifier reviews let you filter by type, so you can narrow down your choice of the best dehumidifier for the environment you want to use it in.
3) Pick the right capacity dehumidifier
A dehumidifier’s capacity relates to how many litres of water it’s able to extract from the air each day.
Too small a capacity, and the dehumidifier will lack the power to draw water in rapidly enough to make a tangible impact on your damp problem.
But opting for a larger capacity than your home needs could mean you spend more money than you need to – and, if you have a tiny home, it’ll likely take up precious floor space, as larger capacity dehumidifiers are usually physically bigger too.
We’ve tested dehumidifiers with capacities ranging from as small as eight litres to as large as 25 litres. If you have a small home, there’s only one of you, and/ or your damp problem isn’t too bad, you can opt for a smaller capacity dehumidifier.
If you have a larger home, there’s more of you creating moisture, and/ or your damp problem is pretty bad, opt for one with a larger capacity.
It’s worth noting that, while capacity can be used as a guide, dehumidifier manufacturers make their capacity claims based on conditions that aren’t representative of the UK climate. So you shouldn’t literally expect a 25 litre capacity dehumidifier to extract 25 litres of water from the air per day.
In addition, our tests have found that dehumidifiers with the same claimed capacity can vary dramatically in performance – for example, we’ve found that you can sometimes get away with a smaller capacity if you buy a desiccant rather than a refrigerant dehumidifier, as they’re more powerful.
The only sure fire way to get a good dehumidifier is to check our dehumidifier reviews.
Read more about capacity and see our pick of some of the best dehumidifiers we’ve tested in our guide on how to buy the best dehumidifier.
4) Make sure your dehumidifier is set up correctly
Dehumidifiers aren’t the most beautiful of household appliances, but resist the temptation to tuck yours away in a corner.
To give it the best chance of extracting the moist air you want it to tackle, it needs to be positioned away from walls, furniture and curtains, so that air can move freely around it.
Keep internal doors open, and external doors and windows closed, while the dehumidifier is running.
You want the dehumidifier to capture humidity from sources all over your home, including the bathroom and kitchen, so placing it somewhere central in your home is ideal.
Closing windows prevents the dehumidifier working harder than it needs to. Damp air gravitates towards dryer spots, and you don’t want damp air outside to be attracted inwards.
5) Drying clothes with a dehumidifier
The best way to dry clothes is outdoors – but, British weather being famously disappointing, you’re probably obliged to hang wet washing indoors at least some of the time. Plus, not everyone has easy access to an outdoor space suitable for hanging laundry.
But drying laundry indoors can be one of the biggest contributors to moisture in the air (see ‘Keep your home as damp-free as possible’, below). A dehumidifier can help here, by speeding up the drying process.
Position your clothes horse in the centre of the room, with your dehumidifier nearby (though not so close that water could drip onto it) and close the doors and windows of that room.
Some dehumidifiers come with specific laundry features, which are designed to create the optimum conditions for clothes drying: low relative humidity (RH) and lots of air movement, such as you might get in your garden on a dry, breezy day.
Some laundry settings are more nuanced than others, and are designed to save you energy and effort by making sure that the dehumidifier works exactly as hard as it needs to, and no harder.
Even without a laundry setting, a dehumidifier will help dry your clothes faster, though, so there’s no need to worry too much if the dehumidifier you’re after doesn’t have a laundry setting. Think of it as a nice bonus if it does.
Which? dehumidifier reviews
We’ve tested more than 50 dehumidifiers and found big differences between the best and the worst. Buy one that’s no good, and you could find yourself more than a hundred pounds lighter but with all the same damp problems you had before.
Here are three we’ve tested in the last month that are designed for different needs. Head over to our full reviews of each to find out what our lab experts thought.
Inventor EVA II Pro 20L R290 (£149.99) – designed for large, heated homes
- Type: Large-capacity refrigerant dehumidifier
- Laundry mode? Yes
The EVA II Pro has three dehumidification modes: silent, medium or turbo. If you’re trying to work or study from home, you can dip the setting down to silent, or up it to turbo if you’ve just had a shower or bath.
It has a humidistat, which monitors moisture levels in the air and adjusts the dehumidifier to maintain the humidity level you’ve selected
The transparent tank allows you to see at a glance how much water it’s collecting and how soon it’ll need emptying.
As with most dehumidifiers, you can also set it up for continuous drainage, by using the hose that’s supplied to empty the dehumidifier directly into a drain.
Read our full review of the Inventor EVA II Pro 20L R290 to find out what we liked and didn’t like about it.
Meaco MeacoDry ABC 12L (£159.99) – designed for small or medium-sized heated homes
- Type: Small-to-medium-capacity refrigerant dehumidifier
- Laundry mode? Yes
The MeacoDry ABC has two fan speeds, a digital display showing the humidity level in the room (useful if you want to keep an eye on how your damp situation is improving), and a humidistat.
You can set this one up for continuous drainage too, although you’ll need to get a hose separately.
Read our full review of the Meaco MeacoDry ABC 12L to find out if it’s a Best Buy.
Ecoair DD3 Classic MK2 (£214.98) – designed for large or small heated homes and unheated rooms
- Type: Dessicant
- Laundry mode? Yes
Smaller-capacity desiccant dehumidifiers can tackle the same sized homes as larger-capacity refrigerants so, despite only having a 10-litre capacity, the Ecoair DD3 Classic MK2 is designed for use in homes of up to five bedrooms.
It has a humidistat, and can be set up for continuous drainage (hose not included).
This is one of the quieter models we’ve tested, but is it also energy-efficient and, most importantly, does it quickly pull plenty of water from the air?
Keep your home as damp-free as possible
You might not realise how much moisture everyday activities can release into the air. Here are a few examples:
| Activity | Typical amount of water vapour produced |
| Bathing or showering | 1.5 litres per person per day |
| Drying clothes in unvented conditions | 5.0 litres per load |
| Washing clothes | 0.5 litres per wash |
| Washing dishes | Up to 1 litre per day |
Table notes: Figures extrapolated from Oxford City Council – Preventing damp and mould
Of course, it’s hard to avoid or cut down on some of these things. But here are some actions you can take to minimise unwanted moisture in your home:
- Ventilate – particularly moisture-prone areas, such as your kitchen or bathroom. Make sure your bathroom fan is working, and not clogged up with dust. Use your cooker hood when cooking and replace the filter regularly. If the weather isn’t too awful, open your windows for at least 15 minutes after cooking or showering to let steam out and improve air quality.
- Keep on top of home-maintenance – check for anything that could lead to damp, such as roof damage after a storm or blocked gutters
- Wipe condensation off windows when you see it – so that the frame doesn’t rot
- Keep your home warm – at least 18 degrees Celsius if possible
- Dry clothes outdoors wherever possible. Avoid hanging clothes over radiators – this can lead to mould, and, if you’re in rented accommodation, make it harder to argue that you’ve used your home in a reasonable way if you get into a dispute with your landlord.
Head to our guide to improving your indoor air quality at home for more advice.
source https://www.which.co.uk/news/2020/12/dehumidifiers-for-tackling-damp-five-ways-to-get-the-most-out-of-your-dehumidifier/