Electric boilers: what you need to know

January 31, 2023

An electric boiler can be used to replace a gas boiler that burns fossil fuels. The answer is yes in smaller homes, but it’s not an easy swap. Electric boilers have both strengths and weaknesses.

An electric boiler solution is similar in size and installation costs to a traditional gas boiler. This could appeal to people who want to reduce their carbon footprint quickly. They could also be a good option for homes that don’t have a heat pump.

Continue reading to learn more about installation and operating costs, compare them to other options and decide if switching to an electric boiler is a good idea.

Existing gas boilers will still be installed, but they are not being phased out. You can still make the switch to electric if you are not ready. Our boiler buying guide offers expert advice on how to buy an efficient gas model.

Are electric boilers worth it?

There is no single solution. It’s important to take the time to compare different systems before you commit your hard earned money. We’ve summarized the main pros and cons of electric central heating boiler. Later in this article, we will go into more detail. Remember that every home is unique. Before making any major decisions, it’s important to get an engineer who can assess your home.

Pros of an electric boiler

  • The boiler produces no carbon emissions, but it emits zero emissions if it uses electricity from renewable sources.
  • Electric boilers can be nearly 100% energy-efficient. Compared to a gas boiler of the same type, they require fewer units (kWh) to produce the equivalent amount of heat.
  • Less moving parts – This reduces the chance of a fault.
  • Less noisy than gas boilers– mainly because there are fewer moving parts. An electric boiler may be more comfortable if it is in an area you spend a lot of time in.
  • They can be placed anywhere in your home – you don’t even need a gas pipe or flue to get to them.
  • There is no risk of carbon monoxide leaking if the gas isn’t burned completely due to lack of oxygen.

Cons of an electric boiler

  • More expensive to use – electricity costs more per unit (kWh) than gasoline. Although the difference in electricity and gas prices may narrow over time, this is a concern right now.
  • Less efficient that heat pumps– Electric boilers cannot achieve efficiencies above 100%, while heat pumps can produce greater heat units than energy used, giving them efficiencies up to 200%, 300% and even higher. Heat pumps are often cheaper to run than electricity-powered ones.
  • The warranties are usually shorter – most last between two and three years. While this does not reflect the likelihood that they will break, it does indicate that you are more likely to be responsible for any faults that occur.
  • Not suitable for larger homes Electric boilers have lower maximum outputs which means they might not be able to provide the hot water and heating needs of larger homes. However, they will work well in smaller homes. We’ll explain why shortly.

What is an Electric Boiler?

An electric boiler operates in a similar fashion to a traditional gas boiler. However, it heats water using an electric current that passes through a heating element. This is essentially a kettle.

To heat water from your radiators, electric boilers can be connected to a central heating system. They also provide hot water for your faucets and showers.

Different types of electric boilers

Electric boilers are similar to gas boilers. They can either be a combination (combi), or heat-only, (regular), boilers.

Combi boilers

Your radiators and taps will heat water ‘on demand. These devices don’t require external hot water storage cylinders and are therefore suitable for smaller properties. They heat water at the rate you require, so they use more power than either a heat-only boiler or system electric boiler.

Boilers that heat only

Heat your radiators directly and then connect to a water tank for hot water.

These are better suited to larger homes that have a higher hot water demand. They heat and store hotwater for you when you use it. This is in contrast to a combi boiler which heats it on demand but may not be able heat it quickly enough to meet your demand.

They take up more space that a combi boiler or system boiler because they require two tanks: a hot water tank to store hot water and a cold water feed container that is usually located in a loft. The latter tank fills up with main water.

Boilers for system boilers

These components are similar to a heat only option. However, the internal components of a heat only boiler, such as pumps or valves, are integrated into the boiler’s body. They do not require a hot-water tank and are therefore space-saving.

Some models come with an integrated hot-water cylinder. These units can be used in conjunction with standard airing cabinets, making them a great option if you have the space.

Read our guide to the various types of boiler for more information.

Electric boiler prices

There are three major costs that you should consider when purchasing a heating system: upfront costs for the boiler and installation, running costs, and maintenance costs.

Electric boilers currently have a lot in common with gas boilers, both in terms of equipment and maintenance, but the running costs are a different kettle.

Installation of an electric boiler costs

The prices for electric boilers off-the-shelf are comparable to those of gas boilers. An electric combi boiler can be purchased for as low as PS1,500 and up to PS2,000. The cost of heat-only electric boilers starts at as low as PS400. If you don’t have them, you will need to add the cost for water tanks.

Professional installation costs are generally similar for electric and gas boilers, as long as they are of the same size. Costs will vary depending on how complex the job is. Changing the location of a boiler will increase the cost.

This assumption is not true. Gas and electric boiler installation costs are generally comparable. You may need to upgrade the electrical infrastructure of your home to support the switch to an electric boiler. This can be affected by:

  • Determine the phase of your home and whether it is suitable for an electric boiler. An electric boiler must be compatible with your home’s electricity supply. Higher energy requirements may call for a switch from one-phase to three phase.
  • This is the size of your home’s incoming supply fuse. It limits the size of electric boilers you can install. We’ll explain more later.
  • The size and power consumption of an electric boiler in watts – the bigger the electric boiler, the more likely it is that your home will require upgrades (eg larger incoming supply fuse). System and heat-only electric boilers are more efficient than combi models.

It is possible for your electrics to need upgrading, which could significantly increase the cost of an installation of an electric boiler.

A local engineer can assess your home for suitability before you consider installing an electric boiler. They will be able to advise you on the best heating system.

Three-phase or single-phase electricity supply

UK households can have electricity supplied by either a single-phase or a three-phase supply. Three-phase is used for buildings with greater energy requirements.

The’main switch” on your fuse box will show you the ‘phase’ of your home’s supply. It’s three-phase if it looks like three switches merged into one, or single phase if it looks like one switch.

You may find that an electric boiler is not the right fit for your home. However, it’s worth having a local expert assess your home before you make any major changes.

Running an electric boiler costs

As it stands now, electricity is significantly more expensive than gas per kWh.

Although electric boilers are more efficient then gas boilers, they still use less energy to perform the same task. However, they are not as efficient as gas boilers that can offset the difference in price. Electric boilers are more expensive than comparable gas boilers because of this.

You may not need heating as much if you live in a small home or your home is well insulated (so heat doesn’t escape easily). In these cases, your heating will be less needed and your electric boiler costs may be lower.

An electric boiler can be run at a lower cost by heating hot water overnight under an off-peak tariff. However, this tariff has more expensive electricity during the day. This is only possible if the boiler has a hot-water tank that can be heated before it needs to be used.

Unless the cost per unit of electricity or gas drops significantly, electric boilers will not be comparable to gas boilers when it comes to running costs. It is possible. However, much of the electricity produced is still gas-generated and the price for electricity is currently tied to the price for gas.

Maintenance costs for electric boilers

Electric boilers are smaller than gas boilers in terms of moving parts. A gas boiler, for example, has a fan that moves air through the boiler to ignite gas and a gas valve that regulates the flow of gas to its burner. These are not necessary for an electric boiler.

On paper, they are less likely to be broken down than their gas counterparts. Although we cannot prove this, it is clear that electric boilers are no less reliable than their gas counterparts.

However, this does not mean that an electric boiler won’t need to be repaired. Parts can run into the hundreds if they are key components like the heat exchanger. To ensure that they are fault-free, manufacturers recommend that electric boilers be serviced every year. This will cost the same as a gas boiler service.

All this being said, the cost of maintaining an electric boiler over its lifetime is likely to be comparable to that of a regular gas boiler.

Garanties for electric boilers

The warranties for electric boilers are usually only good for 2 to 3 years. However, gas boiler manufacturers may offer warranties that can last 10 years or longer.

This is due at least partially to the fact that gas boilers have been a standard feature in most homes. Manufacturers are now competing for customers and offering longer warranties to make their products stand out.

We may see longer warranties as electric boilers become more popular among homeowners.

Are you paying too much for gas boiler repairs and service? Our expert guide will help you understand the costs of boiler repairs and how to get the best boiler service.

Which size electric boiler are you looking for?

An electric boiler’s power output is what determines its size in kW. The larger the output in kW, the more it can heat your home.

The output of electric boilers is typically lower than that of oil or gas boilers. The average size of an electric boiler is approximately 15kW, but you can find gas combi boilers ranging from 20kW up to 40kW.

Electric boilers can be sized well for smaller homes but they may not be able to handle the heating needs of larger homes. This is especially true if you don’t have enough space for a heat only or system boiler. You would need to opt for a combination electric boiler.

The size of the boiler you require will also depend on the size of your home, its insulation, and the number of radiators.

To determine the right size boiler for your home, it is best to have a qualified heating engineer assess it.

Make sure you have a Which engineer if you are looking for an engineer. Trusted Trader. All of them have been thoroughly vetted by the trading standards professionals. No one can be endorsed. 

Electric boilers produce lower power outputs than other types of boilers.

The power output of an electric boiler is limited by its typical capacity and the size of the supply fuse (also called the main electrical fuse). To prevent excessive current from damaging electrical devices or cables in your home, an incoming supply fuse is required.

It is possible to blow the fuse if you have too many electric devices on at once. This is not an issue day-to-day, since the pull of most household appliances won’t be sufficient to blow this fuse. However, electric boilers can be ‘current-hungry’ and will consume more current if it is larger.

It is not a good idea to have an electric boiler that is too big for your home. The size of your home’s incoming supply cable, and the supply fuse will limit this. Installers recommend that you limit the size and capacity of your electric boiler to 50% of the size of your supply fuse.

There are many supply fuse sizes available for UK homes. Let’s assume yours is 100 amps. This means that your home’s electrical equipment can draw up 100 amps at any one time, which includes your boiler.

For example, a 10kW boiler will draw approximately 45 amps while running. This is almost half the power of a 100-amp fuse. A 15kW electric boiler, however, would draw 65 amps while running. This is well over the limit of 50%.

It can be difficult to determine the right size electric boiler for your home. We recommend that you hire a qualified electrician to help you make this assessment.

Is it better for the environment to use electric boilers?

According to the government’s 2021 Heating and Building Strategy, approximately 17% of UK carbon dioxide emissions are caused by heating our homes.

Electric boilers produce no emissions when they are running. However, oil and gas boilers emit them. If you only consider emissions from your home, electric boilers will be better than gas boilers.

It’s not as simple as it seems. The carbon footprint of electricity production is a problem. This will continue until all electricity comes from renewable sources.

It’s not possible for an electric boiler to emit zero emissions at the moment. However, electricity will become more green as we shift towards renewable electricity sources. Comparing this to gas, a fossil fuel that has a large carbon footprint, we can safely say that electric boilers are overall better for the environment.

Gas boilers vs electric boilers

The most obvious benefit of electric boilers to their gas and oil counterparts is that they emit no carbon emissions at home. This helps you reduce your carbon footprint.

A flue is not required so they can be installed on interior walls. This gives you more options for where the boiler should be located in your house. It is easier to install and service high-rise electric boilers if there is no flue, provided that the building has the appropriate electrical infrastructure.

It is still cheaper to heat your home using a gas boiler. Although this could change in the future it is still the case right now.

Due to their limited size, electric boilers might not be able to heat larger homes. This could result in higher hot water demands and may not work well for homes with many bedrooms or bathrooms.

You may also need to upgrade your electrical system if you’re switching from a gas boiler to an electric one. This could significantly increase installation costs.

A gas boiler is still the best way to heat your home for those who live in the UK that are connected to the gas grid. However, this could change in the future and you might decide that the environmental benefits outweigh the higher cost.

If gas is your preferred option, this guide will show you how to make sure that your home has a low carbon footprint.

Alternatives to gas or electric boilers

The boiler, whether electric or gas, is only one method of heating your home. Heat pumps are the most popular option, but there will be other options in the future.

Heat pumps vs electric boilers

In essence, heat pumps work in reverse. Heat pumps take heat from the ground or air and then boost it to higher temperatures using a compressor. You can heat larger homes with them, but they require more space than usual to house an external unit. Your home must also be well insulated to avoid high running costs.

Heat pumps are more efficient than electric boilers in terms of energy consumption. Heat pumps are more cost-effective than electric boilers when installed in a suitable location. Although heat pumps and electric boilers can be more costly than gas to operate, heat pumps may prove to be the best option if gas and electricity prices are balanced in the future.

However, electric boilers can be installed more cheaply than heat pumps. This means that they may still be cheaper to run over their lifetime than an air source heatpump.

However, homeowners will now be able to receive PS5,000 vouchers towards the purchase of a heatpump. It could bring their installation costs closer to those of electric boilers.

For more information on air source heat pump and ground source heat pump, and to see if they are a good fit for you, please read our guides.

Other low-carbon heating options

Although there are not many low-carbon options today, they could increase as we move towards net zero. Here are some to think about:

  • Storage heaters use electricity to heat special heat-retaining bricks over night and then release heat during the day. Modern storage heaters are now available with timers and thermostats.
  • Immersion heating heaters are electric water heaters that heat hot water cylinders. They can be connected to their own power supply through a cable and used as either a primary or backup water heater for combi boilers.
  • Infrared panels  these provide heat by radiation. These panels use less electricity to heat the same amount as storage heaters and electric boilers. However, to enjoy the benefits, there must be no obstruction between you and the heater (just like how the sun warms you, but is cooler in the shade).
  • HeatWayV Microwave Boilers. These heat water the same way as a microwave, but they use a feedback system that allows you to adjust the power consumption. This ensures there is virtually no wasted energy. This year, the company will begin in-home trials.

For more information, see our storage heaters or immersion heaters guide.

Who should be considering an electric boiler?

Although the high operating costs of electric boilers may discourage many from making the switch, there are certain circumstances where an electric boiler might be the best choice.

A reliable local engineer should be sought out when choosing the right heating system for your home. However, an electric boiler may be more viable if:

  • You have a home that is not on the gas grid.
  • If you live in a high-rise apartment, an electric boiler is easier to maintain than a gas boiler.
  • You want to make a more environmentally-friendly heating choice, but your home isn’t suitable for a heat pump (for example, you don’t have the outdoor space).

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