When should you use a dehumidifier?

If you’re dealing with problematic levels of humidity in your home, getting yourself the best dehumidifier can be a great solution. Increased humidity can lead to visible problems such as mould and damp patches, which are common telltale signs that you need to tackle the issue. Dehumidifiers can also be used to treat a room that has recently been plastered, or to dry laundry. But it’s not always immediately obvious when you need a dehumidifier.

In our guide below, we’ll cover how to tell if you need to use a dehumidifier, when you should use one and whether or not they are seasonal items. We’ve also spoken to some industry experts to bring you the most informed advice possible.

Do I need a dehumidifier and when should I use it?

Aneesa Khan, assistant home electricals buyer at VonHaus, says that a relative humidity of 40-60% is ideal.

“If your house has a high humidity level, this could lead to issues such as mould and mildew, which are bad for your health and can even cause issues such as asthma, allergies, skin irritation and headaches,” says Khan.

She adds that humidity can be too high or too low: “Low humidity (below 30%) can also be a problem, as this can lead to problems such as dry eyes or dry skin.”

Chris Michael, managing director at Meaco, has an even more precise target in mind: “The optimum humidity level is between 50% and 55% relative humidity,” he says. “Mould starts to grow at 68% relative humidity. The benefits of lowering the humidity are no condensation, no damp, no mould and clothes dry faster. It will be a more comfortable environment to live in. The air will feel warmer, so you don’t have to turn your heating on as much in the winter. Meanwhile, if the air is too dry, you could be dealing with dry skin, an itchy throat and a dry cough.”

What are the telltale signs I need a dehumidifier?

It’s not rocket science to tell if your home is too damp. Look out for condensation on the inside of windows and doors, sometimes even mould. You might also notice a damp smell or find that clothes are taking a long time to dry.

“Condensation on the inside of windows and doors is a common sign of high humidity levels,” says Aneesa Khan. “Mould and mildew grow in wet environments, so this is a sign that the humidity levels in your home may be very high. Peeling paint and discolouration on the walls or ceilings are also signs of water damage caused by high humidity levels.”

As mentioned above, you might also want to use a dehumidifier to dry laundry, especially if it’s a wet day. Tumble driers cost more to run and aren’t suitable for all clothes, while putting your clothes on the radiator is inefficient and can even make your home more humid. As such, a dehumidifier is a great option for drying laundry.

If you’ve got a recently plastered room or are facing the aftermath of flooding, a dehumidifier can be used to draw out moisture fast.

Are dehumidifiers seasonal items?

Dehumidifiers can be used all year round. In fact, it’s the case that warm air has the capacity to carry more moisture than cold air. Chris Michael, managing director of Meaco, explains: “It’s recommended they are kept on 24/7. Some dehumidifiers are combined dehumidifiers and air purifiers, making them ideal for year-round use, especially to help with seasonal allergies.” Of course, that might not be financially viable for everyone.

Aneesa Khan agrees that a dehumidifier is for life, not just for winter. But during autumn and winter, you might want another to help laundry dry inside.

“During the winter months when the temperature drops, we’re more likely to keep the windows closed. This leads to the perfect environment for damp and condensation,” she explains. “Using a dehumidifier will help to maintain suitable humidity levels and prevent problems such as mould in your home.”

“During the summer months, humidity levels can be higher due to the warmer weather and this can lead to mould as the moist air doesn’t have anywhere to escape to. A dehumidifier is a useful tool to help remove excess moisture from the air even during the warmer periods.”

Should I use a dehumidifier at certain times of the day?

The very best dehumidifiers shouldn’t dry your air constantly. Instead, they will measure relative humidity and dry the air when it’s needed. You can set the target, but experts agree that somewhere between 40 and 60% relative humidity is good.

Chris Michael is a big fan of the 24/7 approach: “For those on variable energy tariffs, running a dehumidifier overnight can be cheaper than in the daytime. Setting the dehumidifier to dry washing overnight can help alleviate laundry tasks if the household frequently uses the washing machine.”

Sleeping within earshot? Look out for quieter dehumidifiers or those that have night modes that dial back noise levels.

Can I leave a dehumidifier on all day?

So long as your dehumidifier has a target that’s in the 40-60% range, then leaving it on does no harm. They can be very energy efficient and the machine should only turn on when needed rather than be working constantly. The benefits far outweigh the cost.

And as Joshua Warren, air treatment expert at electrical retailer AO, says these benefits include “improved comfort, prevention of mould, reduced dust mites and protection for furniture and electronics”.