Here at the heat is on, we put the knowledge of what you need directly in your hands as the homeowner, so you needn’t ask or wait for information from your electrician. Here we give you complete expert guidance for this specific heating element — so you can source all parts needed to ensure a smooth and successful installation of your electric / dual fuel towel rail or radiator when your tradesman arrives.
what is a heating element?
- A heating element is used as the heat source in an electric towel rail or radiator.
- It works by heating the water or oil inside the radiator, in the same way an element heats water inside a kettle.
- We have a full guide on heating elements if you want to learn even more — click here to read the dedicated guide.
temperature control & operation
- The ONE is a unique element from Terma which has been manufactured in matching profiles to Terma radiators.
- Two heat settings: 45°C and 60°C, regulating the internal radiator temperature.
- Multi-colour LED indicator for temperature status.
- 2-hour drying function with automatic shut-off.
- Compatible with external timers and retains settings when powered off.
- Discreet underside control button and miniature front-facing LED panel.
- The shape of the element is 100% in line with the upright bar (collector) on the radiator or towel rail for a completely seamless look.
- There are five different shape options:
- ONE D (D Profile)
- ONE K (square profile)
- ONE R (round profile)
- ONE P (rectangle profile)
- ONE T (trapezium profile)
- When matching with Terma manufactured models (as seen in the images) it will be a seamless look as these are the profiles used by Terma.
- It is possible to fit these elements in other radiators, but the collector shape and size may differ, meaning the element may be slightly narrower or wider.
- This is the external version of ONE, a standard element which can be retro-fitted and screwed into any radiator.
- The internal ONE version has its electric components integrated inside the radiator and cannot be ordered separately - this has to be ordered at the same time as you order the electric towel rail.
remote control
- Includes an Infrared (IR) receiver for use with Terma TTIR portable thermostat/controllers or DTIR wall mounted controllers (sold separately).
- TTIR is a portable thermostat and 7-day timer.
- DTIR is a 24-hour wall mounted timer device.
- The infrared controller adds additional functions and more convenient control options.
- This system allows remote adjustment without needing direct access to the element.
element specifics
- Internal probe lengths vary depending on the selected wattage — refer to the diagram in the image gallery.
- Straight cable supplied, no plug.
- IPx5 rated, suitable for use in bathroom environments.
- Class 1 electrical rating.
colour selection
- We can paint the ONE element in a bespoke colour of your choice.
- RAL palette – any RAL colour which can be made standard "silk", "matt" or extra super matt "soft".
- Special colours – any Terma special colour (reference by name).
- Terma wet paint colours – a range of premium colours which are more metallic in finish.
wattage selection advice
- Choosing the correct wattage heating element is essential for safe and effective performance.
- Select an element with a wattage as close as possible to the radiator’s central heating (hydronic) output measured in watts.
- If the output is listed only in BTUs, convert using the formula: BTUs ÷ 3.41 = Watts.
installation
- Full installation instructions are supplied in the accompanying manual, but the following points are useful to read in advance.
- The element must never be switched on in open air — it must be fully submerged in the heating medium to operate safely.
- The supplied cable is 1.5 metres long and may be shortened or extended (daisy-chained only) as required.
- Heating elements that have been fitted cannot be accepted for change-of-mind returns.
- When installing the element, always use a spanner on the metal neck. Do not apply force to the plastic head.
electrification advice
- Before electrifying any towel rail or radiator, confirm with the manufacturer that the model is suitable for use with a heating element.
- Not all towel rails or radiators are compatible, as internal design and heat circulation vary between models.
- Installing an element into an unsuitable radiator may lead to poor performance or failure, which would not be a fault of the element.
dual fuel advice
- When using this element as part of a dual fuel installation (electric in summer, central heating in winter), the towel rail should be bled regularly.
- Air can gradually build up inside the system, which may cause overheating if the element operates without sufficient water circulation.
- A heating element must never be operated dry, as this can cause excessive surface temperatures and damage towels or clothing.
- This works on the same principle as a kettle — never run it without water inside.
guarantee & replacement
- Backed by a 2-year manufacturer’s warranty.
- The typical lifespan of a heating element is between 4 and 7 years, depending on usage.
- At end of life, the external ONE heating element can be fully unscrewed and replaced as a single complete unit.
