How to look after a dehumidifier

A dehumidifier needs very little care, but skipping it costs performance and can leave a musty smell. Here is a short routine.

Every couple of weeks: the filter

The washable dust filter stops fluff and dust reaching the coils. Homebuilding's maintenance guide advises cleaning it about every two weeks. Vacuum it gently, or wipe it with a damp cloth and warm soapy water no hotter than 40 °C. Dry it fully before refitting it. A clogged filter cuts airflow and makes the unit work harder.

When you notice it: the tank

Empty the tank when the unit stops or its light shows it is full, and do not leave standing water in it for days. Wipe the tank out roughly once a season. If your model has a hose drain, a hose lets it run continuously without you emptying anything. We show hose-drain support on each product page where the maker states it.

When it is a HEPA model

A few dehumidifiers include an air-purifying filter. Homebuilding says that where there is one it needs replacing roughly every three months. Check your model's manual, because intervals vary.

Before storing it for summer

Run it in fan-only or air-purification mode, if it has one, for several hours so the coils dry out. This lowers the chance of mould inside the machine. Then empty the tank and store it upright.

Where to put it

• Near where the moisture is worst, with the door closed.
• Clear of walls and furniture. Which? advises at least 20 cm.
• Not in a bathroom. Keep electrical appliances out of wet rooms.
• Homebuilding advises against a compressor model in a room smaller than 4 m².

Signs something is wrong

• It runs but the tank stays empty. The air may already be dry, or the room may be too cold. See cold rooms.
• A musty smell. Clean the filter and tank, and dry the coils with fan-only mode.
• Ice on the coils. Common in a cold room with a compressor model. Turn it off and let it defrost.

Always follow your model's own manual, and unplug the unit before cleaning. If the machine is faulty, use the warranty. Warranty lengths are on each product page.

Sources: Homebuilding, Dehumidifier maintenance; Which? for placement. General information only.