Heating a cold bathroom

Start with the safety rules

UK wiring regulations divide a bathroom into zones based on distance from the bath and shower. Fixed heating for those zones must be specified and installed for the job, usually by an electrician. A portable plug-in heater is not a bathroom-zone appliance: it belongs outside the splash zones, ideally in a hallway or landing socket, or in a large bathroom well away from water and only where a suitable socket already exists.

Never take a portable heater into a room while you are bathing or showering, never handle one with wet hands, and always follow the instructions supplied with your specific model.

The approach that actually works: pre-heating

Warm the room before you use it, then remove or switch off the heater. Ten to fifteen minutes at 1,000 W to 1,200 W transforms a small bathroom, and costs around 5p to 8p at a 27p unit rate. With a timer you can have the bathroom warm at 6.45am without thinking about it.

Options for a permanently warm bathroom

• Heated towel rail on the central heating circuit — the standard solution, needs plumbing.
• Electric towel rail — installed by an electrician, cheap to run at low output.
• Fixed downflow heater — designed and rated for bathroom use.
• Underfloor heating — comfortable, but a renovation job.

All of these are installation work, which is exactly why so many people pre-heat instead.

Condensation and mould

Warm, damp air condenses on the coldest surface it can find. Three habits fix most bathroom mould: run the extractor fan during and for ten minutes after a shower, keep the room a little warmer so surfaces are not freezing, and wipe down tiles and the window. Heating alone without ventilation moves the problem around rather than solving it.

What size heater for an en-suite?

Most en-suites are 3 to 5 m² and need very little — 500 W to 1,000 W brings one up to temperature quickly. A full family bathroom of 6 to 9 m² is comfortable at 1,000 W to 1,200 W. See the small room heater guide for the method.

Using RapidHeat around a bathroom

RapidHeat is a portable plug-in room heater, not a bathroom-zone appliance. Used sensibly — plugged in outside the splash zones, on a timer, warming the room before you go in — it does the job most people actually want, and then moves on to the bedroom or study for the rest of the day. Read the safety notes supplied with the heater before you use it anywhere near water.