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 Terma SIM element operates at one fixed internal temperature of 65 °C.
- The element thermostatically regulates itself to maintain this operating temperature.
- No timer is built into the element itself; however, it is compatible with an external timer.
- There is no power button on the element — operation is controlled via a switch fused spur.
element specifics
- Straight cable supplied, no plug.
- 26 mm length measured from the thread down.
- 750 mm internal probe length.
- IP67 rated — safe for use in bathrooms.
- Class 1 electrical rating.
wattage selection advice
- Choosing the correct wattage heating element is essential for effective and safe performance.
- As a general rule, select an element with a wattage as close as possible to the radiator or towel rail’s central heating (hydronic) output measured in watts.
- If the heat output of your chosen radiator is listed in BTUs, you can convert this using the formula: BTUs ÷ 3.41 = Watts.
- Selecting a closely matched wattage helps ensure even heat distribution without overheating.
installation
- Full installation instructions are provided in the accompanying manual, but here are some useful notes before fitting.
- Never switch on the element in open air — it must be submerged in the heating medium to operate safely. The element has a safety cut-out if it runs dry, so your tradesman should not test it by powering it on before installation.
- The supplied cable is 1.5 metres long and can be extended (daisy chained only) or cut to length as needed.
- Elements that have been fitted cannot be accepted for change-of-mind returns.
- Note: The cable masking unit at the rear of the element is not supplied and needs to be purchased separately.
electrification advice
- Before electrifying any towel rail or radiator, confirm that the chosen model is suitable for use with a heating element.
- Not all towel rails or radiators are compatible, as internal design and heat circulation affect performance.
- Installing a heating element in an unsuitable radiator may result in failure, which will not be the fault of the element.
dual fuel advice
- When using this element as part of a dual fuel setup (electric in summer, central heating in winter), the towel rail should be bled regularly.
- Air build-up inside the system can cause overheating or damage if the element runs without water circulation.
- The element should never be operated “dry,” as this can cause excessive surface temperatures and damage towels.
- Treat it as you would a kettle — never run it without water inside.
guarantee & replacement
- 2-year manufacturer’s warranty.
- Usual lifespan of a heating element is 4 to 7 years depending on use.
- At end of life, you can simply unscrew and replace the SIM heating element as it is one complete unit.
