Electric Boiler Installation Guide to Fitting & Different Types

James Elston
Written by James Elston
Updated on 19th March 2024
Posted on 4th March 2024
Topic: Boiler Advice

Installing an electric boiler requires proper planning and understanding of the process. Start by selecting the right size and type of boiler, ensuring your home’s power supply matches the boiler’s needs, and engaging qualified professionals.

This article will guide you through each step of an electric boiler installation, providing clear instructions and tips to make the process straightforward and stress-free.

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Electric Combi Boiler Installation Overview

  • Choosing the correct electric boiler requires considering your home’s size, heating needs, and power output, with professional assessments recommended for optimal sizing.
  • Preparation for electric boiler installation includes hiring qualified professionals, obtaining necessary permits, and ensuring the installation site is ready for the high power demands of the boiler.
  • Electric boilers offer environmental benefits over traditional boilers, with zero on-site carbon emissions and the potential to integrate with renewable energy sources, aligning with future sustainability goals.

Determining the Right Electric Boiler for Your Home

Choosing the right electric boiler is a decision influenced by several factors, including the size of your home, your heating and hot water needs, and the power output required from the boiler.

A professional assessment by an electric heating company or a heating engineer can provide expert advice, ensuring that the boiler selected perfectly aligns with your specific needs.

Assessing Your Heating and Hot Water Requirements

  • The size of an electric boiler should match the size and number of radiators in your home, with a standard rule of allocating 1.5kW of boiler output per radiator.
  • Adjustments may be needed for homes with radiators of various sizes and usage patterns, as the standard 1.5kW per radiator may not always apply.
  • If the electric boiler is also needed for hot water, an additional 3kW should be factored into the required output.

This, of course, should be evaluated based on your individual household needs. Assessing your home’s hot water demands involves considering the number of bathrooms, the frequency of baths and showers, and the simultaneous usage of hot water.

Types of Electric Boilers

Electric boilers come in three main types:

  1. Electric combi boiler: These do not require hot water storage cylinders and provide hot water on demand. They are popular in flats and small to medium-sized homes where space is a premium.
  2. Heat-only boilers: These require a separate hot water storage cylinder and are suitable for larger homes with multiple bathrooms.
  3. System boilers: These also require a separate hot water storage cylinder, but they have built-in components, making installation easier and more efficient.

Each type of electric boiler has unique features that make them suited to different scenarios.

Conversely, electric system boilers, which include internal components like pumps, only need a hot water tank, making them ideal for homes with high hot water demands.

For larger homes with an existing traditional heating system involving a separate hot water tank and often a cold water storage tank in the loft, heat-only electric boilers are well-suited.

Single-Phase vs. Three-Phase Electricity Supply

The type of electricity supply your home has is another important factor to consider when choosing an electric boiler. Most domestic homes feature a single-phase electricity supply, typically used when lesser power is required, including homes with gas central heating.

  • Three-phase electricity supplies are typically used in larger properties and commercial buildings with a higher power demand.
  • Electric boilers up to 12kW can operate on a standard 230V single-phase supply.
  • Boilers ranging from 18 to 24kW require a 400V three-phase supply for operation.
  • It’s always best to consult a qualified electrician to assess your overall power requirements and determine the appropriate electricity supply (single-phase or three-phase) for your electric boiler installation.

Upgrading to a three-phase supply can be costly and should be considered only if the electric demand, including the boiler, exceeds what a single-phase supply can accommodate.

Preparing for Electric Boiler Installation

Once you’ve determined the right electric boiler for your home, it’s time to prepare for the installation process. This involves:

  1. Hiring qualified professionals
  2. Obtaining necessary permits
  3. Preparing the installation site to ensure a smooth and compliant electric boiler installation.

Hiring Qualified Professionals

The complexity of electrical and pressurised hot water systems involved in electric boiler installations necessitates hiring skilled electrical or heating engineers.

These professionals should be proficient in handling both plumbing and electrical activities, especially when converting from gas to electric heating systems.

Apart from the installation, heating engineers are also responsible for ensuring that the electric boiler complies with Building Regulations, which includes verifying the presence of a third-party electrical assessment label on the boiler.

Hence, it’s recommended to hire a company that provides certified electricians, plumbers, and Gas Safe engineers for a complete and compliant electric boiler installation service.

Obtaining Necessary Permits

Before commencing the installation of an electric boiler, it’s critical to acquire any necessary permits or approvals.

Electric boiler installations must adhere to relevant building regulations and safety standards. A reputable installation service will assure that your electric boiler installation is fully compliant with these regulations.

It’s also important to manage the proper disposal of the old boiler in accordance with local council regulations for safety and compliance.

Preparing the Installation Site

Before the electric boiler installation, the home’s electrical infrastructure should be checked to ensure it can handle the high power usage of an electric boiler. This includes:

  • Checking the condition of the wiring, especially in older buildings
  • Ensuring the installation site has a dedicated electrical supply circuit with a correctly sized circuit breaker
  • Making sure the electric boiler is not supplied from a ring main

Implementation of a dedicated breaker at the distribution board, connected with the correct size and type of electrical cable, is essential for safe operation.

It’s also important to install an isolation switch near the electric boiler for safe maintenance and emergency situations.

The space-saving design of electric boilers allows for flexible installation locations, often reducing installation complexity and costs.

The Electric Boiler Installation Process

With the groundwork laid, we can now proceed to the actual installation process. This involves:

  1. Safely disconnecting and removing the existing gas or oil boiler
  2. Installing the new electric boiler
  3. Performing necessary tests to ensure the boiler operates efficiently and safely.

Removing the Old Boiler

The first step in the installation process is to safely disconnect and remove the existing gas or oil boiler. The removal of a gas boiler includes the safe capping off of the gas line by a certified heating engineer.

For the removal of an oil boiler system, it’s necessary to also remove and safely dispose of the oil feed and the old oil tank.

The process of boiler removal also involves taking out the flue, which vents combustion gases, as well as the condensation pipe from condensing boilers. Any residual openings left by these components need to be properly sealed for safety.

Installing the New Electric Boiler

Once the old boiler is safely removed, it’s time to install the new electric boiler. The boiler is secured in place, ensuring it is correctly levelled and in the appropriate location for the power supply and plumbing connections.

Plumbing connections for electric boilers typically involve a simple cold input and hot output for system boilers, with additional connections for domestic hot water in combi boilers.

Control of an electric boiler is achieved through room thermostats that connect to a control circuit. For instance, ThermoSphere boilers require a wired connection to a °C terminal for heat call and a 3 Amp supply for controls.

Lastly, a system cleanse is performed to remove debris like black magnetite from the system, followed by the addition of a corrosion inhibitor to protect against rust and hydrogen gas formation, thereby ensuring long-term efficiency.

Testing and Commissioning

Following the installation, a series of checks, tests, and adjustments are performed to ensure efficient and safe operation of the boiler. This process, known as boiler commissioning, ensures that the new electric boiler meets performance and safety criteria.

Maximising Efficiency and Reducing Running Costs

With the electric boiler installed and operational, understanding how to maximise its efficiency and reduce electric boiler running costs becomes more important.

Proper use of energy-efficient settings, controls, and integration of renewable energy sources can significantly enhance the efficiency of your electric boiler.

Energy-Efficient Settings and Controls

One way to enhance the efficiency of your electric boiler is by setting a room thermostat to the lowest comfortable temperature, typically between 18 and 21 degrees Celsius.

This can save energy without compromising comfort. Programmable room thermostats allow different temperatures to be set for different times of the day, enabling users to heat their home more efficiently.

Thermostatic radiator valves (TRVs) enable individual room temperature control, and boiler interlocks can save energy by only operating the boiler when heating is needed.

Moreover, monitoring energy consumption through smart electric boiler controls can optimise boiler performance and indicate potential issues for proactive maintenance.

Integrating Renewable Energy Sources

In addition to smart controls and efficient settings, integrating renewable energy sources like solar panels can result in significant reductions in energy use and costs. Some benefits of solar thermal systems include:

  • Direct heat capture from the sun
  • On-demand hot water with storage tanks
  • Decreased electric boiler operation
  • Lower running costs
  • Enhanced energy independence

The use of solar batteries and hybrid solar thermal systems ensures that renewable energy is available even during periods with less sunlight, optimising heating systems to be more renewable-centric and reducing electric boiler dependency.

As the push for sustainable energy intensifies, electric boilers can be effectively integrated with renewable resources, such as solar and wind power, by using the appropriate inverters.

Maintenance and Troubleshooting

While electric boilers offer a safer installation option due to the absence of a flue and no risk of harmful gas leaks, they still require regular care and maintenance to ensure optimal performance.

From performing a system cleanse to eliminate sludge and debris to troubleshooting common issues, let’s delve into how to maintain and troubleshoot your electric boiler.

Annual Servicing

To maintain peak operating condition and ensure efficient performance, an annual boiler service for the electric boiler is key.

Even though it’s not legally required, it’s advisable to regularly service your electric boiler to prevent potential issues and maintain efficiency.

During the annual service visit, the professional will:

  • Check safety valves, components, and wiring to identify issues such as discoloration caused by improper connections or incorrect cable sizing
  • Test the system’s performance
  • Examine specific parts such as electrical connections and the heating element for proper function

Regular maintenance is important to ensure the safe and efficient operation of the system – see the cost of an electric boiler service here.

Common Electric Boiler Issues and Solutions

Despite their high efficiency and safety, electric boilers can sometimes encounter issues. One common problem is the boiler failing to turn on, which could be due to power supply problems and is often indicated by error messages or the absence of the power light.

Another common issue is low water pressure, which stops the boiler from operating and typically requires re-pressuring the system after checking for leaks.

RCD tripping may signal an overloaded circuit or an earth leak, requiring verification of the circuit load and checking for leaks.

And if the electric boiler is functioning but fails to produce heat, this could be due to an issue with the heating elements, diagnosable through current or resistance checks.

Regularly activating the electric heating system for short periods, even in warmer months, can help prevent the boiler components from seizing and thus reduce the risk of breakdowns.

Environmental Impact and Future Prospects

Switching to electric boilers provides not only energy efficiency and cost savings but also contributes to a greener future.

Electric boilers produce zero on-site carbon emissions and can significantly improve local air quality, making them a more environmentally friendly choice than gas boilers.

We will now further explore the environmental impact and future prospects of electric boilers.

Carbon Emissions and Climate Change

As a heating solution, electric boilers have a clear edge over gas boilers and gas and oil boilers in terms of carbon emissions.

Unlike gas boilers that emit greenhouse gases when burning natural gas, electric boilers do not produce onsite emissions during operation. This feature helps support efforts to reduce greenhouse gas emissions.

The overall carbon footprint of electric boilers currently depends on the carbon intensity of electricity generation. However, this can be mitigated by:

  • Increasing the proportion of renewable energy sources in electric power production
  • Implementing energy efficiency measures in the design and operation of electric boilers
  • Promoting the use of electric boilers in conjunction with other renewable energy technologies, such as solar panels or wind turbines

With the push towards carbon-neutral energy sources, electric boilers could play a significant role in achieving a sustainable future, as opposed to traditional oil boilers.

The Future of Electric Heating Systems

Looking at the future of electric heating systems such as air source heat pumps, flexible grid systems and demand side response technologies are expected to support the widespread use of electric heating solutions in both residential and commercial sectors.

Electrically heated buildings have a greater potential to participate in demand side response schemes, which not only allows them to manage energy consumption more effectively but also offers the opportunity for financial incentives.

The UK government’s Review of Electricity Market Arrangements (REMA) presents a strategic effort to improve energy security and reduce the cost of electricity.

This initiative is likely to facilitate the broader adoption of electric heating solutions, making electric combi boilers a more sustainable option for the future.


From determining the right electric boiler for your home to understanding the installation process, maintenance, and troubleshooting, we’ve explored the ins and outs of electric boilers.

Their high energy efficiency, zero on-site carbon emissions, compatibility with renewable energy sources, and suitability for a wide range of properties make them a promising solution for modern heating needs.

While electric boilers currently have higher running costs than gas boilers, advancements in technology, government initiatives, and a growing focus on sustainable energy sources are likely to make them a more cost-effective and eco-friendly option in the future.

It’s clear that electric boilers are not just a temporary trend, but a key player in the transition towards a sustainable, energy-efficient future.

Frequently Asked Questions

How much does it cost to have an electric boiler installed?

The cost of installing an electric boiler can range from £650 to £2,500. This range accounts for different factors such as the complexity of the installation and the need to move the boiler, but not all installations will be at the higher end.

Can I install an electric boiler myself?

It’s highly recommended to have a skilled electrical or heating engineer install an electric boiler, as it requires expertise in electrics and pressurised hot water systems, which can be dangerous if not handled properly.

What is the downside of electric boilers?

The downside of electric boilers is that they tend to be more expensive to run and the production of the electricity used as fuel emits greenhouse gases.

This means they are not recommended for homes with higher heating and hot water demands unless paired with a renewable energy source.

Is it worth installing an electric boiler?

Yes, installing an electric boiler is worth it due to its advantages, including safety from carbon monoxide leaks and the potential to reduce your home’s carbon footprint by using renewable energy sources.

What are the factors to consider when choosing an electric boiler?

Consider the size of your home, your heating and hot water needs, and the required power output when choosing an electric boiler. Seeking advice from a professional electric heating company or a heating engineer is recommended.

Written by
James Elston
James Elston Director Of Boiler Central
Posted on: 4th March 2024
Topic: Boiler Advice

James Elston is our resident boiler replacement and heating expert here at Boiler Central. With over 20 years experience in the boiler installation industry, James ensures that he knows everything there is about our Gas Safe boiler installations, energy saving and home heating solutions. This can be from simply procuring the latest best combi boilers, to reviewing and ensuring that Boiler Central maintains the highest standards across our boiler installation company.

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