Dehumidifier FAQ


What does a dehumidifier do?

Dehumidifiers remove water vapour from the air to create a cleaner, healthier environment; they’ll even help you dry your laundry more quickly too, especially in the winter.

“A compressor dehumidifier is almost like a mini-fridge that cools the air and converts it into water that you can pour away,” says Ryan Kandola, a dehumidifier expert from Aircon Centre, “whereas desiccants take the air and run it over a rotating flywheel which absorbs the moisture, before heating it so the wheel doesn’t get saturated.”

How do you know when you need a dehumidifier?

The recommended humidity for your home is 40-60 per cent in the summer months and between 30-50 per cent in the winter. You can measure it with a hygrometer (a humidity gauge – they’re not expensive).  If it goes over 70 per cent, you run the risk of condensation, damp, mould, fungi and bacteria. That’s when you need a dehumidifier.

Which is better, a compressor or desiccant dehumidifier?

Compressors are generally efficient at room temperature, but they can’t handle the winter cold so well. If the temperature drops below three or four centigrade, they will tend to stop working. That’s not the case with desiccants, although they can be more expensive to run.

How to use a dehumidifier

It’s simply a matter of setting the desired humidity level and the unit will do the rest. What you will need to do is empty the water tank from time to time.

Where should you place a dehumidifier?

For a bathroom, you should position the dehumidifier just outside the bathroom door and ensure the door is left open so the unit can draw the moist air towards it. If you’re drying clothes, just place the dehumidifier in the room, making sure the door and windows are all closed.

“If there’s a problem room, the dehumidifier should be kept in there, preferably with doors and windows closed,” says Chris Wood, also from Aircon Centre. “If it is to be used to control the moisture for the whole house, however, then it should be located centrally, on a landing or in the hallway, and the air from the rooms should be able to flow towards the units. So keep the interior doors open and the exterior windows shut.”

How much does a dehumidifier cost to run?

Look for one which draws less than 330 Watts and you will never spend more than 10p per hour. It’s often much less on lower power settings. Dehumidifiers are generally cheap to run. 

What size dehumidifier do I need?

Domestic dehumidifiers can extract up to 25 litres of water per day. We have largely focused on 20l models since these are the most popular for domestic use. For larger spaces, damper environments or colder temperatures, choose something more powerful. (Or vice versa for smaller spaces.)

* The cost of one kiloWatt-hour of electricity is capped at 30p under the Energy Price Guarantee as of July 2023. Although prices do vary by region and contract (economy 7 tariffs are more expensive by day and cheaper by night, for example), we use the capped price to estimate running costs.

View the latest John Lewis & Partners and Very deals

By admin

Leave a Reply

Your email address will not be published. Required fields are marked *