Electric Boiler Heating System UK: A Comprehensive Guide

Electric boilers have become a popular choice for home heating and hot water in the UK, particularly in properties without access to a gas supply or where gas boilers are not feasible. This comprehensive guide delves into the key aspects of electric boiler heating systems in the UK, including the size of boilers and radiators needed, the requirement for a hot water cylinder, and the efficiency of electric heating.

What Size of Boiler or Electric Radiators Do I Need?

The size of the boiler or electric radiators required depends on several factors, including the size of the property, the number of radiators, and the desired temperature. Here are some detailed guidelines:

Boiler Size

Electric boilers come in a wide range of sizes, ranging from 4kW to 48kW. The appropriate size for your home depends on the following factors:

Property Size: As a general rule, a 12kW electric boiler can heat a small to medium-sized property, while a 24kW boiler is suitable for larger homes. For example, a 12kW boiler can typically heat a 3-bedroom house with an average floor area of around 100 square meters.
Number of Radiators: The number of radiators required will also influence the boiler size. As a guideline, a 12kW boiler can typically power around 10-12 standard-sized radiators, while a 24kW boiler can handle 16-20 radiators.
Insulation and Thermal Efficiency: Well-insulated homes with good thermal efficiency may require a smaller boiler size, as less energy is needed to maintain the desired temperature.

Electric Radiators

The number and size of electric radiators needed depend on the size of the rooms and the desired temperature. Here are some general guidelines:

Minimum Radiator Size: As a rule of thumb, you should have at least one radiator per room, with a minimum of 500W per radiator.
Radiator Sizing: To calculate the required radiator size, you can use the formula: Radiator Output (in Watts) = Room Volume (in cubic meters) x 10. For example, a room with a volume of 30 cubic meters would require a radiator with an output of at least 300W.
Radiator Placement: It’s important to position the radiators in the most effective locations, such as under windows or in areas with high heat loss, to ensure optimal heat distribution throughout the room.

Do I Need a Hot Water Cylinder?

A hot water cylinder is necessary if you want to store hot water for later use. Electric boilers can be used with both vented and unvented cylinders, which can be indirect or direct:

Indirect Cylinders: These are the most common type and use a coil to heat the water, with the boiler providing the heat source.
Direct Cylinders: These heat the water directly using electricity, without the need for a coil.

The size of the hot water cylinder required will depend on the number of occupants in the household and their hot water usage. As a general guideline, a 150-liter cylinder is suitable for a 1-2 bedroom property, while a 210-liter cylinder is more appropriate for a 3-4 bedroom home.

Is Electric Heating Efficient?

Electric boilers are highly efficient, with some models reaching efficiencies of up to 99.8%. This is because they do not lose heat through flues like gas boilers, making them a good option for well-insulated homes. However, the overall efficiency also depends on the source of electricity used to power the boiler:

Renewable Energy: If the electricity is generated from renewable sources, such as solar, wind, or hydroelectric power, the electric boiler system can be highly efficient and environmentally friendly.
Grid Electricity: When using grid electricity, the efficiency of the system is influenced by the energy mix used to generate the electricity. The more renewable sources in the grid, the more efficient the electric boiler system will be.

Technical Specification of Electric Boiler Heating System UK

Here are some detailed technical specifications to consider when choosing an electric boiler heating system for your UK home:

Electric Boiler Types

There are two main types of electric boilers:

Direct Electric Boilers: These heat water on demand, providing hot water and heating as needed.
Storage Electric Boilers: These heat and store water in a hot water cylinder for later use.

Boiler Efficiency

Electric boilers typically have very high efficiencies, ranging from 99% to 100%. This is due to the lack of heat loss through flues, as well as the direct conversion of electricity into heat.

Hot Water Cylinder Compatibility

Electric boilers can be used with both vented and unvented hot water cylinders, which can be either indirect or direct:

Vented Cylinders: These use the mains water pressure to supply hot water and require a cold water storage tank.
Unvented Cylinders: These use the mains water pressure directly, without the need for a cold water storage tank.
Indirect Cylinders: These use a coil within the cylinder to heat the water, with the boiler providing the heat source.
Direct Cylinders: These heat the water directly using electricity, without the need for a coil.

Electricity Costs

The cost of running an electric boiler can vary depending on the size of the boiler and the household’s usage. On average, electricity costs around 14.4 pence per kWh in the UK. For example, a 12kW electric boiler running for 2 hours per day would cost approximately £1.73 per day (based on the average electricity rate).

DIY Considerations

While electric boilers are generally easier to install and maintain than gas boilers, it is still recommended to hire a professional heating engineer for the installation. This ensures that the system is installed correctly and safely, meeting all relevant building regulations and safety standards.