Guide written by:
John, DIYer & IT developer, Brighton
If your bathroom radiator has trouble heating up, why not combine it with a additional heater? Choosing the right secondary heating system based on the size of your room and how fast you want your heater to warm up will allow you to warm up your bathroom by a few degrees and improve your day-to-day comfort.
- Operating mode
- Safety guidelines
- Size of bathroom
- Type of heater
- Heating options
Why use an additional heater?
As the name suggests, backup heating devices are made to complement an existing heating system, either because it's lacking in power or it only works intermittently. You might need to rely on one if your central heating ever gives up the ghost. If you live in a flat and the communal heating system is off, you'll need to sort something out so baby doesn't get cold coming out of the bath!
An electric radiator is always an option, but can be a bit lacking in power ‐ especially in the depths of winter. Inertia heaters produce a lovely gentle heat, but to warm you after a 5-minute morning shower it won't heat up in time! A bathroom heater should heat up quickly and powerfully to give you a sensation of warmth in a short period of time.
It should also be easy to move about, so you can put it away when not in use or use in another room if necessary. Finally, it should be easy to install and require minimal maintenance. Just set up, plug in and away you go!
What important safety guidelines are there?
Just like any electrical appliance, a space heater mustn't be placed on or near a water source such as a sink, shower or bathtub. Splashes of water interfering with the circuitry can have disastrous consequences.
Standard electric radiators should be placed at least 1.2m from a sink and 3m from a bathtub. These are big distances to stick to if you're looking at a tight bathroom space. However, heaters designed specifically for bathrooms will have some form of splash protection and can therefore be placed as near as 60cm from a bath or shower and right next to a sink.
Bathroom heating devices may be subject to specific design standards. (In France, standard IP21 indicates that water will run off the appliance, and objects larger than 12mm can't get in and disrupt its workings.) Basically, you're safe if you choose a specifically designed bathroom space heater and place it as far as practically possible from water sources to further minimize risk.
What type of space heater to choose for your bathroom?
Several types of heaters are available, varying in terms of tech level, purchase cost and mode of use as well as the level of heating comfort they provide.
First sold in the 1960s, this type of appliance heats the air via radiation, through the same principle of liquid intertia as a fixed liquid intertia radiator. Mounted on casters, oil heaters are easily recongized by their sheet steel ridges 5 to 10cm apart in which the oil circulates. These heaters are powerful and relatively economic (since the inertia principle allows them to keep returing heat once switched off), but also heavier and bulkier.
They can be used in any room of the house and are available at power ratings of up to 3000W – or enough to heat a room 30m² with normal insulation and ceiling height. One downside is that they take a while to heat up because the oil needs to rise in temperature.
Mobile radiating panel
The radiating panel emits a significant portion of the energy consumed as infrared radiation. This spreads around the space in inverse proportion to the distance from the heater. Essentially, anything near the heater heats up – including your legs if you happen to be standing in front of it. They can produce a feeling of warmth even in fairly cold ambient air. These heaters also have a weaker convective effect, achieving greater overall heating comfort than a traditional convector for less energy. They're quite quick to heat up, and should be set up a good distance from the user and from furniture (can discolour surfaces).
An electrical resistor, either in contact with the air or contained within a ceramic block, heats the air put in motion by a fan. This forced convection can heat a large volume of air in a very short time and limits the stratification effect produced by a traditional convector. It does inevitably make a noise, however, so if you like absolute peace in the bath, or listening to your favourite radio programme, make sure you choose a quieter model or one with adjustable fan speeds.
In larger bathrooms, an oscillating feature can be used to send hot air in all directions and thereby heat the entire room. Some fan heaters can also be fixed to the wall. Always follow manufacturers' guidelines and make sure the fan can take in enough air to avoid overheating. A clearance of 5cm at the back is usually sufficient. These heaters are light, easy to move around and store, and generally have a range of heating speeds. Last but definitely not least, make sure your model is intended for bathroom use. Unlike with the other types of heater, you'll find something to suit here if you have a smaller bathroom. Fan heaters can be ceramic-block (improved heating quality) or resistor-only (cheaper).
These consist of a heating element (>1000°C) protected by a grille, containing a filament and a halogen gas that emits infrared radiation. Often coming in the form of a strip installed above the sink or on a piece of bathroom furniture, these heaters are usually operated with either a pull-cord or a button. They heat up quickly and are mainly used in smaller bathrooms. The heating element needs to be replaced every 5000 hours and it's worth bearing in mind that they can be more dangerous than the alternatives.
What options and features are available?
All these types of heaters can be bought with extra features to enhance their use, economy and performance.
This feature allows the heater to reach its operating temperature more rapidly. Great if you're pushed for time. This is achieved at the expense of efficiency, leading to greater energy consumption.
The heater can be set to turn itself off when a set time has elapsed. Great if you want it on while you shower and don't want to fret all day about whether you turned it off. A timer socket can always be used to the same end.
Unlike with a mechanical thermostat, it limits temperature jolts resulting from sudden on-off switching. In high-efficiency operating conditions, it uses less energy while producing a superior heating effect.
An essential feature if you want to be able to use your heater in all seasons and temperatures. Heating speeds vary between appliance types: 2 on fan heaters; 2 or 3 on oil heaters, etc.
Which heater's best for my bathroom?
It's difficult to make a space heater truly efficient because efficiency depends on thermal inertia – and this process is drawn-out as it requires a solid or liquid body to heat up first (dry or liquid inertia) before returning the heat to the surrounding air via radiation.
If you can programme or start your heater at least 30-40 mins before you plan to use the bathroom for a long period of time (i.e. 2 hours!), an oil heater is perfect. Where these two conditions don't apply, it's not the one.
A spacious bathroom - over 6m² - justifies installing a radiating backup heater. If positioned wisely, it should heat the bathroom by several degrees within 15 mins.
If you're always on the go and want an almost immediate temperature gain in a small bathroom, then go for a fan heater: under normal operating conditions, it'll only take 5 mins to heat the room! Ideal for small areas (up to 5m²).
Convectors are basically not the best option for a bathroom. They can be OK if you're looking for a heater for general use around the house rather than a specific backup heater for the bathroom.
Learn more about bathroom design...
To find out more about bathroom design, follow our editors' advice and check out their other guides:
How to choose your bathroom sink?
How to choose your bathroom heater?
How to choose your household insulation?
How to create a good bathroom layout?
How to choose your heated towel rail?
How to choose your auxiliary heaters?
How to choose your electric radiators?
How to choose your hot water radiators?
How to choose your boiler?
How to choose your shower rail?
How to choose your shower cubicle?
How to choose your shower door and walls?
How to choose your shower handrail?
How to choose your bathtub?
How to choose your bathroom units?
How to choose your toilet?
How to furnish your bathroom?
Guide written by:
John, DIYer & IT developer, Brighton, 70 guides
Since I was a child, I was always interested in manual and technical works. Always fascinated by woodworking, I took advantage of my first flat as a playground. On the cards: electricity (of course, safety first!) and some partition walls; but also decorating with the help of the missus, made-to-measure furniture and little tricks to optimise the space, all the while remaining as original as possible. When the little one arrived, I started building bits and pieces for him! Lacking space, I have not got a permanent workshop and certain tools I dream about but are not part of my collection. Not to worry, I already know a lot about DIY and I have a high-tech profile that I hope will guide you in your decisions!