The best ways to use and maintain your dehumidifier

If your home suffers from mould and damp caused by excess moisture, a dehumidifier can be a powerful, cost-effective way to deal with the problem and keep clamminess at bay. However, not everyone knows how to use a dehumidifier effectively, or how to keep it in good working shape. It’s not that dehumidifiers are difficult to use or onerous to look after, but there are some basic mistakes that can affect how well it works, or even reduce its lifespan.

In our article below, we’ll give you some tips on how to get the best use of your dehumidifier, and how to keep it in tip-top condition.

How to get the most out of your dehumidifier

To get your dehumidifier working at its best, it helps to know a little about what it does. Dehumidifiers operate by sucking air in from around the room, drying it out, then pushing the dried air out through an exhaust. Most dehumidifiers use a compressor to cool the air so that the water condenses and drips into a tank, while others use a rotating wheel full of desiccant material that soaks in the moisture and is then heated to dry it out. In either case, airflow plays a vital role in how the dehumidifier does its job.

Find the right spot

Because of this airflow, dehumidifiers need space to work. While it seems sensible to put it close to a cold, damp wall where you know you’re battling mould and condensation, you might be limiting the airflow and preventing the dehumidifier from working at its best. While some dehumidifiers are designed to work closer to a wall – from maybe 20cm away – most work better if pulled out towards the centre of the room. This gives them plenty of space to draw in moist air from all around the room, and expel the warm, dry air.

Focus on your dampest rooms

You probably know which rooms are most affected by damp and mould, and where you’re struggling most with condensation. If you’re not sure, bear in mind that in the UK east-facing rooms tend to get less sun and build up higher levels of humidity. The same will be true of rooms with large external walls or windows, and less-used rooms that don’t get as much heating. Some of the larger, higher-capacity dehumidifiers can deal with a whole floor or apartment at once, but moving a smaller dehumidifier from room to room can help you tackle the worst-hit spaces.

Close your windows but keep internal doors ajar

Opening your windows when it’s a little warmer outside or after you’ve been cooking, showering or ironing will help you reduce the humidity inside.

However, you’ll also bring cold air in during the winter, which could add to your heating bills. Crucially, you don’t want those windows open when your dehumidifier is active, as it will endeavour – ineffectively – to dry this cool air coming in on top of the warmer air inside the home. So, close your windows while your dehumidifier is at work, but leave internal doors slightly ajar. This helps keep that all-important airflow moving, so that your dehumidifier can do its job in style.

Stay on top of the problem

One mistake people sometimes make is to use their dehumidifier sparingly, letting moisture build up between runs. Instead, use it regularly to keep on top of problem areas or rooms. Automatic or eco modes can be a big help here: they’re designed to run your dehumidifier at the most effective level to reach your target humidity and hold it there. Scheduling features in app-enabled smart dehumidifiers can also work well to make sure your dehumidifier isn’t sitting around doing nothing. You can even set up routines for some models using Google Home or Alexa, so that your dehumidifier is triggered when the humidity level hits a certain point. For this, you’ll need a smart dehumidifier and compatible air-quality monitor, but it could be worth it.

Don’t go too wet or dry

Be sensible about your target humidity. The ideal relative humidity level in the UK is between 50% and 60%. Go higher, and you’re more likely to have problems with damp and mould. Go lower and your air could be too dry, aggravating conditions like asthma or eczema. You’ll be using energy unnecessarily with diminishing returns, and you might even create conditions that some bacteria enjoy. Usually, 50% to 55% is the sweet spot.

Dry your laundry the right way

There’s little point using a dehumidifier if you’re going to dry your clothes on radiators in the room. You’re just releasing more moisture back into the air and undoing your appliance’s hard work. Instead, get a clothes airer and use your dehumidifier’s drying function. Set up the dehumidifier near the laundry rack and position the outlet so that it blasts warm air towards your clothes – this will help them dry that bit faster. Turning the rack around halfway through is another great idea. Don’t worry if your dehumidifier doesn’t have a laundry mode. Running it in continuous mode with a six-hour timer can work well, or even just using it in its normal or automatic mode. If you’re looking to buy a dehumidifier and your main reason for doing so is to dry clothes, then consider one of our favourite dehumidifiers for drying clothes.

Keep it warm

Warm rooms are easier to dry, so try to avoid low temperatures and set your dehumidifier running while the room’s still fairly cosy. If it’s a sunny day, let in as much sunlight as possible to get the temperature rising. It all helps. Some spaces, especially conservatories or garages, can be too cold for compressor dehumidifiers to work. If that’s the case, think about investing in a desiccant dehumidifier. These are usually more effective in cold spaces.

Maintaining your dehumidifier

Dehumidifiers aren’t particularly complex or breakdown-prone appliances and should last you for years of use, provided you take some simple steps to keep them clean and working properly.

Empty the water tank often

Most dehumidifiers will pause and give you an alert if the water tank needs emptying, but it’s a good idea to empty it at least daily, and preferably after every use. The water isn’t distilled and may contain dust, bacteria, airborne particles and mould spores, but that doesn’t mean it needs to go to waste. It’s safe to water houseplants or ornamental plants and trees outside, provided you’re not using it to water fruits or vegetables that you’re going to eat. You also shouldn’t drink it. You could use it in a steam iron or steam cleaner, as it will have fewer minerals than tap water. Alternatively, pour it in your compost bin. It can help speed up decomposition.

Clean the filter

Every dehumidifier has a filter to clean out dust and other impurities as the air travels through the machine. It’s best to remove and clean this roughly every two to four weeks, according to the manufacturer’s instructions. A quick brush and a gentle clean with a vacuum cleaner’s nozzle should do it, but you might need to wash the filter in warm water with a mild detergent. Once it’s washed, air dry it thoroughly before you put it back in the machine. Generally speaking, the filter should last as long as the dehumidifier, but spares should be available if yours has got damaged – or if you’ve let it get so spectacularly filthy that it’s beyond salvation.

Some dehumidifiers may also work as air purifiers and have an additional HEPA filter. These are often more fragile and more difficult to clean. Instead, they’re usually designed to be replaced every six to nine months. Follow the manufacturer’s advice to keep it working well.

Steer clear of the coils

The condensing coils in a compressor dehumidifier can get dirty if the filter isn’t working at its best, but it’s not a good idea to clean them directly. In fact, accessing them and cleaning them manually might invalidate the warranty, and break safety regulations too. If there’s obvious build-up of dust, disconnect the dehumidifier from the mains and use a vacuum cleaner and brush without removing any grille. Otherwise, leave well alone.

Turn off before you unplug

When you’ve finished using your dehumidifier, turn it off on the control panel before you turn it off at the wall. Most need to spin down fans, drain the system and cool elements before shutting down, and can’t do so if you yank out the plug or turn it off at the mains. This can cause problems for the components and reduce the dehumidifier’s useful life.

Keep it clean

Keeping the body of the unit and the water tank clean will also keep your dehumidifier working effectively for longer. Wipe the surfaces down, remove the water tank and give it a good clean with a sponge or cloth and soapy water. Make sure the vents are clean of dust and hair. This all goes double if you’re packing a dehumidifier away for the summer – and double check that you’ve emptied the water tank. For one thing, you’ll get nasty smells next time you turn it on. And take it from one who’s learnt the hard way: tipping a litre of six-month stagnant water down your trousers isn’t something that you want to do.