Heating elements are key aspects for electric and dual radiators which work off the main electricity supply rather than the central heating system. Electric radiators need to give off a lot of heat at a reasonable temperature, such as electric towel radiators. Effectively, a heating element is a sturdy electrical component designed to throw out heat when a big electric current flows through it.
What Is a Heating Element?
Typically, a heating element is a coil, ribbon or strip of wire that gives of heat. Much like a lamp filament, a heating element gives off heat when an electric current flows through it. It glows red hot and converts the electric current into heat, which then radiates out in all directions.
A heating element is usually nickel-based or iron-based, with some nichrome being a popular choice of material. Nichrome is an alloy – a mixture of metals and sometimes other chemical elements. The main reason why it’s a popular material used to make heating elements is because:
- It has a high melting point
- It doesn’t oxidise or expand under high temperature
- It has reasonable resistance
The shape and size of the heating element largely depends on the required heat output and the dimensions of the appliance it needs to fit inside. There are lots of different types of heating elements – you may be more aware of what one is than you think. There are many day-to-day examples of heating elements that provide heat in many day-to-day appliances and tools. Here are a few examples:
- Hair curlers – these have short, coiled heating elements because they need to produce heat over a thin tube around which hair can be curled.
- Electric stoves – these have coiled heating elements just the right size to heat cooking pans and pots with many stoves covered by metal, glass, or ceramic plates to ease the cleaning process.
- Electric radiators – these have long bar elements because they need to throw out enough heat to warm a large room. Electric convector heaters generally have concentric, circular heating elements positioned in front of or behind electric fans (so they transport heat more quickly by convection).
In some appliances, heating elements are very visible. For example, the ribbons of nichrome built into toaster walls, and the coiled electric element in the bottom of kettles.
Dual Radiators & Towel Rail Heating Elements
A great example of heating elements in radiators would be the type used in dual radiators. A dual fuel radiator is connected to both your central heating system and your electrics with the addition of an electrical heating element and a T-piece. This means that your radiator can be heated either by the central heating system, or electrically via the heating element. There are numerous benefits of investing in a dual radiator.
The main benefit of using dual radiators is the flexibility they provide homeowners. With unpredictable weather changes throughout the year, dual radiators allow you to heat rooms in your home without having to switch the central heating on. Since they can be turned on and heated without the need for central heating, they can be especially useful for keeping you warm during seasonal weather changes. For example, when we go from Summer to Autumn, it’s too warm to turn all the radiators back on, but you can feel the cold when you step out of the shower – our dual towel rails are perfect for this.
Towel rail heating elements are used to power normal towel radiators that are connected to the central heating, using mains electricity. Typically towel rail heating elements are inserted from underneath where the controls to moderate the temperature are easily accessible.
At Stelrad, we stock a great range of towel radiator heating elements in different lengths and wattage outputs to cater for many different sizes of towel rail radiators. You’ll find these among the many other radiator accessories we stock online.
Factors that Impact Radiator Heating Elements Performance & Longevity
Several factors determine the performance and longevity of radiator heating elements. Here is a handful of examples:
Watt Density – watt density is the heat delivered by a heating element per unit area. The right watt density must be used to ensure the efficiency of the heating elements. High-density elements can reach much higher temperatures which leads to premature burning or failure of the element. In selecting a heating element, check the manufacturer’s recommended watt densities for a particular application.
Temperature – the target operating temperature directly affects the watt density.
Power supply – the heating element must be able to operate with the available power supply. This is vital to its performance. Check the voltage rating which is typically 120V or 240V. It’s important not to exceed the power supply circuit breaker tripping point or the ratings of the power cables.
Fluid flow – stagnant fluids are easier to heat with controlled temperature than flowing fluids. Air or other gases do not generally absorb heat quickly because of their low density. A solution would be to slow down the flow, but most of the time, this is not an option. Thus, heaters with large surface areas are required. Finned surfaces and long wire coils (low-density heating elements) are the usual features of air heaters.
Temperature Sensor Location – conventional heaters come with a temperature sensor and a controller. In most applications, the sensing device only measures the temperature of the process fluid. Note that this does not usually represent the actual heating element temperature. Before installing the heater and the temperature sensing device, check if its location is appropriate for the heater unit. If the sensor is too far, the temperature reflected may be much lower due to heat dissipation and low heat transfer rate. This can lead to very high temperatures that can burn the heating element.
Corrosion – corrosion can be from the process fluid or the external environment. The sheathing material protects the heating element, leads, and insulators from chemical attack. Thus, the sheath must be able to maintain its strength in high temperatures while being resistant to corrosion. Widely used sheathing materials are stainless steel, brass, copper, and other special alloys. Moreover, the integrity of the sheath and terminal sealing must be sufficient for the application. For demanding applications, hermetic sealing is the best option in providing complete protection from the process fluid.
These are a handful of different specifications you can check over before investing in radiator heating elements.