Electric boilers

Electric boilers

There are a few different types of electric boiler:

Electric Combi Boilers

An electric combi boiler is similar to a gas combi boiler and provides both central heating and hot water from a single unit, usually mounted on a wall. They are often the cheapest and easiest type of electric boiler to install. As a direct, ‘on-demand’ system an electric combi boiler does not store hot water, so you don’t need a hot water tank, which saves space. However, this means you can’t take advantage of smart tariffs by heating your water overnight at a cheaper rate.

Electric Storage Boilers

Storage electric boilers use electricity to heat and store hot water in a built-in hot water cylinder or a separate hot water tank. Water can therefore be heated using off-peak electricity, like economy 7, providing potentially cheaper running costs. However, they are often more expensive to buy and install and take up more room than an electric combi boiler.

Dry Core Storage boilers

Dry core storage boilers are similar to electric storage boilers in that they utilise electricity during off-peak hours but they store the heat in a dry medium, usually bricks. The heat can then be released into water when it’s needed, and used for central heating or hot water, which often provides savings since electricity prices are usually higher in the daytime. 

Electric Combined Primary Storage Units

Electric combined primary storage units (CPSUs) are mainly suited to commercial buildings, such as hotels, with very high demands for hot water. They store a large volume of hot water within the boiler, so can provide hot water at a faster speeds and higher pressures than other kinds of electric boilers. Electric CPSUs are not suitable for most homes as they take up a lot of space and are far more expensive than standard boilers.

Solar PV Compatible electric boiler systems

A solar compatible boiler does not really refer to a type of electric boiler. It simply means a system with a hot water storage tank with an immersion heater, to which you can divert ‘excess’ electricity from your solar photovoltaic panels to heat water during the day. You can combine solar PV systems with a gas boiler and an immersion heater, or an electric storage boiler. 

How do electric boilers work?

Electric boilers are supplied with cold water from a homes’ mains water supply. When hot water is needed for the central heating or hot taps, the cold water is passed through an electric heating element to warm it and the hot water is pumped to your taps or radiators as needed. Electric boilers can have a limit to the amount of domestic hot water they can produce instantly, which is why an indirect cylinder is often used, especially if the home has a bath.

Electric boiler efficiency

Electric combi boilers are much more efficient than most gas boilers and typically have a 99%–100% efficiency rating. The higher efficiency means you wont need to burn as much energy to generate the same amount of heat, but since electricity is much more expensive than gas the running costs for electric are considerably more than gas boilers. Most electric boiler companies claim you will use less than half the amount of energy to heat your home and hot water using electricity in comparison to gas.

Advantages

  • Quick and easy to install
  • Relatively low installation costs in comparison to other forms of heating.
  • Relatively small so can easily fit in the place of an old gas combi boiler and hence are well suited to smaller homes.
  • Virtually silent
  • Electric boilers work well in conjunction with solar energy
  • No risks of carbon monoxide leak
  • Few moving parts mean less chance of any problems
  • Zero carbon when powered by renewable electricity
  • No need for a flue pipe, so can be installed anywhere in the home

Disadvantages

  • Electric boilers have higher running costs than other fuel types.
  • If the electricity is cut off due to a power cut, you won’t have access to any heating.
  • Not always able to meet higher demands for heating and hot water

Electric combi boiler costs

Prices for electric boilers are coming down as more manufacturers enter the market and prices are likely to reduce further in the coming years. That said, they’re already cheaper and easier to install than a gas boiler and a standard combi boiler can cost as little as £1,500 installed going up to £4,500 for a system with a storage tank. The biggest factors affecting the final price you pay will be the power rating of the boiler you choose and whether you need a hot water storage tank or not.

Running costs will vary depending on the size of your home, how many radiators you have and how well insulated it is, as well as how long you run your heating and what temperature you want to heat your home to. Typical running costs for an electric combi boiler rate at 11kWh, sufficient to power 8 radiators will currently cost you about £2,500 per year. (at early 2023 electricity prices)

Electric dry core storage boiler costs

An electric dry core storage boiler, which stores heat in bricks, will cost more to install but less to run than an electric combi boiler. Typical installation costs for an average 3 bedroom home will be between £4,500 to £6,500 and running costs will be approximately £1,700 per year, presuming you have access to economy 7, or cheaper night rates for electricity. If you can’t get cheaper electricity at night a dry core storage boiler does not have many advantages over an electric combi boiler – you might be able to get more hot water but you won’t see any savings.

Is an electric combi boiler worth it?

Whether an electric combi boiler is worth it depends on your home setup. For smaller homes, flats and properties which aren’t connected to the gas network, an electric boiler is definitely worth considering. Gas combi boilers do have lower running costs and are better suited to heating larger homes, or those with higher hot water requirements. But, when combined with solar PV, to either power the electric boiler directly, or from a battery, or when solar PV can be used to preheat stored water, electric combi boilers provide a smart, zero carbon option. The simple installation process and flexibility to locate an electric combi boiler anywhere in the home also offer significant advantages.

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Check out the other alternatives to gas boilers in our energy guide.