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How to use a dehumidifier

Updated: 21 October 2026

The tank is still dry after an evening, and you are wondering if the unit is broken. How to use a dehumidifier is the room you shut, the target you set, and the water you remove. Open windows, a dial left at 30%, or a tank you never check will make a working compressor look useless. This is the operating page for the machines in the [dehumidifier comparison](/hub/cooling/dehumidifier). It does not rank them. Peter F. used UK how-to sources and the listings on 20 October 2026. Placement figures are rules of thumb, not a lab trial. A qualifying purchase can earn a commission at no extra cost to you.

The tank is still dry after an evening, and you are wondering if the unit is broken. How to use a dehumidifier is the room you shut, the target you set, and the water you remove.

Our top picks

Pro Breeze Pro Breeze 12L/day

Best overall

Pro Breeze Pro Breeze 12L/day
8.8/10about £134.99
View offer
ARIBIO ARIBIO 12L/day

Best value

ARIBIO ARIBIO 12L/day
8.0/10about £129.99
View offer
Bosch Bosch Dry 1000

Rank 3

Bosch Bosch Dry 1000
7.3/10about £159
View offer
On this page
  1. 1.Where it has to stand
  2. 2.Windows, doors, and the setpoint
  3. 3.Tank, hose, and the first night
  4. 4.When it is not collecting water

Where it has to stand

Put it on a firm floor in the damp room, vents clear. Humidity Helper suggests about 20–30 cm from the walls. That is a rule of thumb, not a clearance on every listing. A Bosch or an ARIBIO at 10.5 kg stays on the floor. A mini can sit in the cupboard its millilitre rate can treat. Do not stand any of them in shower spray. None of these listings states an IP rating. Shut the worst room rather than every door in the flat. If the carton says to stand a compressor upright first, do that. Use a BS 1363 socket.

Windows, doors, and the setpoint

External windows and doors stay shut while it runs. You are drying a fixed volume of air, not the street. After a shower or after cooking, air the room briefly, then close up before you switch the dehumidifier on. An open fanlight all evening is the usual reason a tank stays empty. If there is a humidistat, start near 50%, inside a 40–60% comfort band. That is guidance, not a legal limit. The Pro Breeze and the ARIBIO run from 30–80%. Holding 30% all day keeps the compressor on after the windows have cleared. The ARIBIO does not remember the humidity limit, so check the display later.
Pro Breeze Pro Breeze 12L/day

Testsieger

Pro Breeze Pro Breeze 12L/day
8.8/10about £134.99
View offer

Tank, hose, and the first night

Compressor tanks in this set hold 1.7 to 2.5 litres. A real multi-litre day means several trips unless a hose is on. The ARIBIO, Pro Breeze and Devola describe a hose. The Bosch listing does not, so plan to empty the 2.5 litre tank. Route the hose downhill to a drain you are allowed to use. If it rises, the water stays in the tank. These boxes do not include a pump. Humidity Helper suggests 12 hours or more at first, and about 4–8 hours beside laundry. Both are a starting range. Drying a wash is on the dehumidifier for drying clothes page. Do not leave it on overnight unless the manufacturer allows unattended use. A full-tank shut-off is not that permission.

When it is not collecting water

An empty tank in a cold room is often a limit, not a defect. One Bosch review says automatic mode will not run if the room is too cold. Meaco’s class example is that a basic compressor can stop extracting below about 12°C. Heat the room and try again before you return the unit. One Senelux note recorded about 50 ml in 8 hours, against about 250 ml a day at 30°C. Check the window, the tank seating and the timer before you assume a fault. On the ARIBIO, a forgotten setpoint can mean it never stops. Unplug a plug that is too hot to hold. A growing patch or a tide mark needs a plumber, a landlord or a surveyor.

Common questions

Should the windows be open?
No, not while it is running. You are drying the air in that room, and an open fanlight replaces it with outdoor air. Air the room briefly after a shower or after cooking, then close the windows and switch the dehumidifier on. A permanently open window is the usual reason a tank stays empty in a home that still feels damp at breakfast.
What humidity should you set?
If you have a humidistat, start around 50% relative humidity, inside a 40–60% comfort band. The Pro Breeze and the ARIBIO can be set from 30–80%. Leaving the target at 30% all day keeps the machine on harder than an occupied room needs. The ARIBIO may forget the setting, so check it again later. A mini with no setpoint simply runs until the tank is full or the timer ends.
Why is the tank still empty?
The usual causes are an open window, a room that is too cold for the coil, a tank that is not clicked home, or a mini whose real collection is a few tens of millilitres. Heat a cold room and close it before you assume a fault. One Bosch review says automatic mode will not start if the room is too cold. A 30°C test-point claim on a Peltier unit will not appear as a full jug in a British winter evening.
How does a hose have to be routed?
Downhill, all the way, to a drain you are allowed to use. The ARIBIO, Pro Breeze and Devola describe a hose or tube. If the hose rises, water will not leave the tank. These boxes do not include a pump. The Bosch listing does not state continuous drainage, so that model is a tank you empty by hand. Check the joint after the first hour so a loose fitting does not wet the floor.
What do you do if the plug gets hot?
Unplug it and stop using it. One Senelux review says the wall adaptor became too hot to hold. That is a fault, not a warm-up. Do not cover the adaptor or move it to a thinner extension lead to share the heat. Use the returns route while you still can, and do not leave a hot plug in a socket overnight.

Related pages

Dehumidifier buying guide

Dehumidifier

Best dehumidifier: Pro Breeze top pick, ARIBIO value

Dehumidifier for condensation: what it can and cannot do

Dehumidifier for drying clothes beside an indoor airer

Sources

Public UK sources named below. amazon.co.uk prices, stars and review counts on these listings were read on 19 October 2026. Page updated 20 October 2026.

  1. GOV.UK damp and mould guidance (1 April 2026) (retrieved 2026-10-20)
  2. GOV.UK Awaab’s Law tenant guide (retrieved 2026-10-20)
  3. NHS inform (retrieved 2026-10-20)
  4. NICE NG (retrieved 2026-10-20)
  5. Electrical Safety First (retrieved 2026-10-20)
  6. Electrical Equipment (Safety) Regulations (retrieved 2026-10-20)
  7. Which? indoor clothes drying (retrieved 2026-10-20)
  8. energy.org.uk (3 October 2026) (retrieved 2026-10-20)