Use a dehumidifier properly

Run a dehumidifier at the right humidity, empty and clean it regularly, and tackle damp's real cause.

DH-01Check why the room is damp firstA dehumidifier helps with condensation and drying laundry indoors, but it won't cure rising damp, a leak or penetrating damp from outside. Look for patches near skirting boards, mould in corners, or water on cold windows. If you find a leak, a crack outside, or damp coming up from the floor, get that sorted first — the dehumidifier will just be masking the real problem.

DH-02Pick the right spot for itStand the unit in the open, at least 150-200mm from walls and furniture so air can circulate all round it. Put it centrally in the room, or near the main source of moisture, such as a wet window or a laundry airer. Don't block the air intake grille or stand it right up against a wall.

1 each · Dehumidifier (compressor, 10-12L/day)

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DH-03Set it up safelyPlug it straight into a wall socket rather than a chain of extension leads. Route the cable so it doesn't cross a walkway or trip anyone. Keep curtains, clothes or anything else clear of the air outlet, and never sit anything on top of the unit while it's running.

DH-04Set the target humidityUse the humidistat dial or display and set it to 50-60% relative humidity. That's comfortable and stops mould growing. A lower setting makes it run more and cost more to use. Most units switch off automatically once the target is reached and start again if humidity rises.

DH-05Close the room up while it runsShut doors and windows so the unit isn't pulling in fresh damp air from outside. If you're drying clothes, keep the door closed and open a window briefly at the end to clear the muggy air. Running it with windows open all the time wastes electricity, as it can never catch up.

DH-06Empty the water tankCheck the tank daily at first — most hold 2-4 litres and stop automatically when full, usually with a light or beep. Empty it into a sink or drain. Don't leave water sitting in the tank for days, as it can start to smell or grow mould.

DH-07Clean the filterPull out the washable filter monthly, or weekly if you use the unit a lot. Rinse it under a tap and let it dry fully before refitting. A clogged filter cuts how well it works and can blow mould spores round the room.

DH-08Keep an eye on running cost and noiseA typical dehumidifier draws 150-350 watts. Running it 8 hours a day costs roughly £0.20-£0.50 a day at current electricity prices. Most units run at around 45-55 decibels, so only leave one running overnight if it has a quiet mode.

DH-09Tackle mould and tidy upOnce humidity is down, wipe any mould spots with a mould and mildew spray and a dry cloth. When you're finished using the unit for a while, empty and dry the tank fully, wipe down the casing, and store it upright somewhere dry — never on its side, as leftover water inside can leak out.

1 each · Mould and mildew spray

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