Electric Boilers: The Complete Guide

How much electricity does an electric boiler use?

Electric boilers are more expensive than gas-fueled boilers due to the rising costs of energy we are currently facing in the UK. 

As of April 2022, electricity in the UK costs on average 28.3 p/kWh. For those on an Economy 7 tariff, it costs 16.7 p/kWh during off-peak hours, and 34.1 p/kWh during peak hours. 

Economy 7 tariffs provide cheaper electricity rates during the night, and pricier ones during the day. They are intended for people with storage heaters, which draw electricity in the evening or through the night, and release the energy during the day when needed. 

Fuel prices from the Energy Saving Trust as of April 2022.

Types of electric boiler

Electric boilers are just as flexible as gas boilers in regards to their set up, with a boiler type available for most needs. 

Electric Combi Boilers

Electric combi boilers are the exact same as gas combi boilers, but obviously use electricity instead of gas to heat the water. It provides all the heating and hot water to a household from a single wall hung unit. 

They do not need a separate hot water tank to hold the water.

Storage Boilers

A storage electric boiler can help to reduce energy bills. It is supplied with a hot water tank, either within the unit or as a separate unit itself. They are often more expensive than electric combi boilers. 

Electric CPSU

A Combined Primary Storage Unit (CPSU) stores a lot of water within the boiler so it can meet demand much quicker and at a higher pressure. These boilers tend to be quite large, and are therefore more suited for commercial installations.

Dry Core Storage 

Dry core storage boilers are similar to storage boilers, and are designed to work alongside Economy 7 tariffs for cheaper energy prices at night. 

They work by heating bricks overnight, and then releasing this heat into the water for hot water and central heating.

Solar Compatible 

You can use solar panels to heat your water during the day for free if you have a storage tank with an immersion heater.

How do you know what size electric boiler you need?

The power output of a boiler is measured in kilowatts (kW), and helps to give an idea of the the level of heating and hot water demand that the boiler can meet. 

The higher the kW rating, the more taps and radiators the boiler can supply at one time. 

As a general rule of thumb, add 1.5kW per radiator in your home. For example, if you have 4 radiators, you will need a boiler with a power output of 6kW.

What are the running costs of an electric boiler?

The price you pay for electricity will depend on your tariff, as well as the area of the UK you live in. The average price of electricity in the UK is 14.4 p/kWh per unit, compared to gas boilers which is only 3.8 p/kWh. 

While this is quite a difference, many people cannot heat their homes with gas. 

There are several ways to reduce running costs:

• Install solar panels for free renewable energy
• Switch to an Economy 7 tariff that offers reduced rates of energy during the night
• Heat water stored in a hot water cylinder

The best electric boiler brands

If you are looking for an electric boiler, there are plenty of options with a range of models and manufacturers.  

Comet Combi Boiler by Electric Heating Company

The Comet Combi boiler includes a 140-litre Duplex stainless steel hot water cylinder to maximise the volume of hot water. It is also compact in design and is pre-wired and pre-plumbed for easy installation. 

This boiler is available in outputs of 9kW, 12kW or 14.4kW. You can also select heating only, hot water only or use both at the same time. The Comet includes a 2 year warranty on the boiler, with a 10 year warranty on the cylinder. 

Electromax by Heatrae Sadia 

The Electromax boiler provides both heating and hot water to your home at the same time, as it combines a hot water storage cylinder and circulating pump with an electric flow boiler. 

The boiler has a 180-litre Duplex stainless steel unvented cylinder, enabling it to deliver mains shower pressure, fast filling baths and a balanced supply of hot water to multiple tap outlets. 

It is available in two sizes for domestic use of 6kW and 9kW, and includes a 2 year warranty on the boiler and a 10 year warranty on the cylinder. 

THERMAflow

The THERMAflow High Efficiency Electric Boiler is designed to operate during periods of cheaper electricity tariffs to reduce your running costs and energy use, while still meeting your heating and hot water demands. They claim this can save users up to 40% on their heating. 

This boiler can be connected to a wood burning or solar thermal system to reduce your electricity usage, carbon footprint and heating bills. The THERMAflow is available in six outputs of between 10-18kW. It also includes a 1 year warranty on the boiler and 25 years on the cylinder. 

Electric boiler warranties

Generally, the warranty on boilers is split by the boiler itself and the cylinder. The two will not have the same warranty. 

Most boilers will come with a 1-2 year warranty on the boiler, and 10 or more years for the cylinder depending on the make and model.

Electric boilers vs gas boilers

Whilst natural gas is a great way of heating homes, there is no hiding from the environmental impact caused by homes up and down the country using gas boilers. 

Electric boilers are a great way to combat the damage gas causes to our environment, especially for smaller homes and apartments. However, they are unable to meet the same demands for heating and hot water in larger homes compared to gas boilers. 

Electricity is also more expensive to run than gas boilers, and most of the electricity is made up by burning fossil fuels, although renewable energy is also an option to power electric boilers. 

Gas boilers are the most affordable boilers on the market, but they do run the risk of breaking down or releasing carbon monoxide if they are not annually serviced. 

Each type of boiler has its own pros and cons, and which one you choose all depends on your household needs and affordability. 

Does an electric boiler cost more than a gas boiler?

Yes, as we mentioned earlier, electric boilers are more expensive to run than gas boilers. Natural gas is the cheapest way to heat your home, which is why gas boilers are the heating system choice of UK homeowners. 

Electricity in the UK costs on average 28.3 p/kWh. Whereas, gas boilers cost on average 7.4 p/kWh, making it the cheapest option out there. 

Fuel prices from the Energy Saving Trust as of April 2022.

Do electric or gas boilers heat your home better?

Electric boilers have an efficiency rating of 99-100%, and gas boilers have a maximum efficiency rating of 93%. This means with every £1 that is spent heating a home, 7p is lost on wasted energy. 

However, whilst electric boilers boast a 100% efficiency rating, they have an ErP D rating, compared to the A rating of many gas boilers which makes it hard to compare boilers of different fuel types. 

Despite this, renewable energy generation has increased massively over the past few years. This means there are times when electricity has a lower carbon intensity than natural gas. This could lead to the ErP ratings for boilers being increased sooner rather than later.