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What’s inside an electric radiator?

Electric radiator profiles

Electric radiators have come a long way from the unsightly heat blasters they used to be. 

In fact, most of our designer radiators are now available as electric options. So you don’t have to sacrifice excellent design for quality technology and performance. They offer all the above. 

There are also some similarities in the way that electric radiators and central heating radiators work in terms of fluid heating up, expanding and transferring through the surface of the radiator to heat the cold air.  

But what is inside electric radiators that allows them to work so well?

Please note:

Forget about electric fan heaters, storage heaters, infrared radiators, electric heat pumps and other types of electric heaters for now. This article will focus on what’s inside our electric designer radiators.

What are electric radiators filled with?

Unlike standard radiators, electric radiators are not filled with water. 

Instead, electric radiators are filled with oil or a thermodynamic fluid called glycol. 

All of our electric radiators at BestHeating come pre-filled with glycol.

But what is it and why do we use it to power electric radiators?

Milano Windsor Traditional Anthracite 3 Column Electric Radiator
Chemicals dropping into test tube

What is glycol?

The glycol inside our electric radiators is a ready to use propylene glycol based non-toxic heat transfer fluid with anti-freeze and anti-corrosion inhibitor functions designed for heating systems and sealed radiators. 

This means it has a low freezing point and has inhibitors which don’t cause the metal to rust. 

Propylene glycol is commonly used in Heating, Ventilation and Air Conditioning (HVAC) but it is also used in food and pharmaceutical process cooling applications.

Why are electric radiators filled with glycol?

There are lots of benefits of filling electric radiators with glycol. 

Glycol is great at:

  • Retaining heat.

This thermodynamic fluid is designed to cool down slowly. So even when the electric radiator has stopped using power from the mains, you’ll still experience ambient heat in the room.

  • Preventing a build-up of rust and limescale. 

Since glycol contains anti-corrosion inhibitor, it is designed to prevent the metal inside the radiator rusting and filling the system with sludge. This means that the system will function efficiently and reduce maintenance costs for corrosion damage. 

  • Transferring heat.

Although glycol is around 5-10% less efficient than water at transferring heat, as little as 1/16″ of scale reduces heat transfer by 40%. And since glycol prevents the build up of dirt and scale, this more than makes up for the slight loss of efficiency. 

  • Eliminating the kettle type noise from inside the radiator.

When water boils it can create kettle noises in central heating systems. Whereas this non-toxic glycol fluid insulates sound, meaning reduction of noise during use.

  • No need to bleed or balance the radiators.

Glycol filled electric radiators require very little maintenance and don’t require bleeding or balancing like central heating radiators.  

  • Antifreeze protection.

The glycol solution contains antifreeze to protect the radiator if temperature falls below -7°C. So there is no danger of the system freezing up even during the harsh winter.

Is glycol safe?

There are two different types of glycol:

  1. Ethylene glycol
  2. Propylene glycol

Ethylene glycol used to be used in the HVAC industry. However, experts have moved away from this compound because of its toxicity. 

However, propylene glycol is a safe, non-toxic compound that is now commonly used by HVAC experts (including us!).

The Food and Drug Administration (FDA) has also classified propylene glycol as an additive that is “generally recognized as safe” for use in food.

When it comes to installing your electric radiator, in some cases you may notice a slight leakage of the glycol solution. 

This sometimes happens to our electric radiators in transit and is nothing to worry about.

If that is the case you can easily top up the radiator with water, making sure to leave a small space for the heating element.

Propylene glycol under a magnifying glass

What else is inside electric radiators?

So glycol does a great job of conducting heat. But how does it heat up in the first place? 

That’s where the heating element comes in.

Each one of our electric radiators and heated towel rails is supplied with a heating element which is a type of a submersible electrical resistor that transforms electrical energy into heat energy.

These clever elements are what make electric radiators 100% efficient because they turn every unit of electrical energy drawn from the wall into heat energy.

As the heating element heats up the glycol, the radiator surface area heats up and the warm air flow circulates throughout the room via convection.

Since electric power is expressed in Watts, instead of measuring the heat output in BTUs like we are used to with central heating radiators, electric radiators measure heat output in Watts. 

The higher the wattage, the more heat is provided.

But don’t worry, our BTU calculator does the conversion for you to give you more of an idea of how much heat to expect from your electric radiator.

And therefore, whether an electric towel radiator can heat a bathroom or any other space, to give a specific example.

Terma heating element
Milano heating element

The element is a chrome rod that simply slides into the bottom of the radiator. We stock a couple of different models with various functions depending which type of radiator you choose. 

For example, the Terma elements are Bluetooth controlled. Whereas the Milano Connect range is Wi-Fi connected.

The heating elements also have an IP rating (Ingress Protection) which tells you how protected the element is against dust and water.

All our heating elements are IP64 and above designed to offer a high level of dust and water protection for the preservation and maintenance of electric radiators.

Do electric radiators plug in?

There are lots of different types of wall mounted and portable electric radiators and some of them are designed to plug in to your electrics with a standard plug. 

However, at BestHeating we only stock electric radiators that must be hardwired into the mains electrics. We would always recommend that this should be carried out by a qualified electrician.

Ready to go electric?

Now we have finished delving into what’s inside our electric radiators, go and check out the different ranges we stock below.

shop link to electric designer radiators category

electric heated towel rails link to the store

Concerned about running costs? We’ve got all the info you need right here.

Still unsure whether an electric radiator is right for you? Head over to our should I buy an electric designer radiator guide.

Ready to find your favourite? Shop our stylish collection of electric radiators.

If there’s anything you think we haven’t covered and would like to ask us a few questions, leave a comment below, or say hello on social!

Frequently Asked Questions

All electric radiators from BestHeating are filled with a thermodynamic fluid called glycol, which enables them to operate with the utmost efficiency.

Glycol is used because it is excellent at retaining and transferring heat, and incorporates an anti-corrosion inhibitor to prevent rusting.

Further information can be found in our blog, What’s Inside an Electric Radiator?

Electric radiators are filled with a thermodynamic fluid known as glycol, which enables them to operate with such extreme efficiency.

This solution is then warmed up by an efficient electrical heating element, that transfers energy to the solution, enabling all touchpoints within the radiator to get to a nice warm and comfortable temperature.

Find out more about the solution, and the make-up of electric radiators in our Advice Centre blog, What’s Inside an Electric Radiator?

There are a multitude of benefits to both electric and plumbed radiators, with both types offering unique properties and advantages.

Electric radiators, filled with glycol, can operate independently of a central heating system, whilst plumbed rads rely on the central heating to work.

Consult the BestHeating Radiator Buying Guide to help you decide on the perfect style of radiator to suit your space.

Our electric radiators are supplied pre-filled with glycol, a rust and corrosion-resistant heating solution.

The glycol used in the Milano range of electric radiators is PM20 Solaris Inhibited Heat Transfer Fluid.

If you want to know more about electric radiators and how they operate, check out or guide on what’s inside an electric radiator. Or, for inspiration surrounding all styles of radiators, explore our definitive radiator buying guide.

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