The name ‘Combi’ comes from the boiler’s ability to efficiently ‘combine’ producing heat for hot water and central heating at the same time. A ‘combi’ differs from other types of boiler by delivering instant hot water. It uses the domestic water supply rather than feeding the hot tap from a storage tank. In contrast, an electric system boiler heats mains water and stores it in a tank.
Because a combi electric boiler only uses electricity as fuel, the installation and purchase costs of an electric boiler are cheaper. Costs start at about £500 up to models costing £2,500. The average cost to buy a 9kW electrical boiler works out about £1,500.
Although an electric boiler installation costs less than other boilers, using electricity as fuel will give you higher energy bills than using oil and gas as fuels. However, an electric central heating boiler needs less maintenance, fewer replacement parts and fewer safety inspections. It also has a smaller carbon footprint than other types of combi, with less carbon dioxide and other waste gas emissions. It also only uses just enough energy to heat the water. Whereas, burning its own fuel wastes a lot of heat. So, throughout the boiler’s lifetime, it probably works out to be at least the same overall costs, but probably significantly less. Also, it has the advantage of being ‘greener’ than oil and gas fuels.
We mustn’t forget too, that most homes in the UK draw power from the National Grid or can generate their own electricity. So, we don’t have to be connected to mains gas, don’t need to store oil at home or even use bottled gas. Let’s face it, electricity is convenient, and electric boilers for heating and hot water are probably most convenient of all.
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Main Topics
How Much Do Electric Boilers Cost?
Electric combi boilers are a great choice if you want to replace your gas boiler with an electric one. However, you need to ask a professional to calculate the correct size for your circumstances. The demand for hot water and how many radiators you have in your house will determine the size of the combi and the electric boiler efficiency. You may already have electric storage heaters. In which case, consider whether you want to continue with those or change to electric wet central heating using radiators or underfloor heating.
Electric boiler cost calculator
There are different combi boilers available for you to choose from. The prices shown in the table are for purchase only, exclude VAT and don’t include installation.
| Boiler type | Power (kW) | Price |
|---|---|---|
| Without built-in storage tank | 12kW | £900 to £1,500 |
| With built-in storage tank | 12kW | £1,500 to £2,500 |
| Wall-mounted with storage tank | 3 to 15kW | £1,750 to £2,000 |
| Floor-standing with storage tank and warranty | 10 to 18kW | £2,350 to £4,500 |
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Types of Electric Boilers
When you consider buying a boiler, the main factor that governs your choice should be the size of the boiler and power output. These determine the amount of hot water you receive and how hot the water becomes.
Assume your home has insulated cavity walls, double glazed doors and windows, and the recommended depth of loft insulation (270mm). You have 5 rooms and about 85m2 floorspace. As a general rule, you’ll need 1.5kW per radiator, or if you have underfloor heating then it’s 70W/m2. Therefore, we need 8kW for central heating or 6kW if you have underfloor heating. Most homes aren’t as perfectly insulated as this so ask a professional for a complete home survey to decide on the size boiler you need.
You should also consider the type of boiler you need, as some are better suited than others for different budgets and properties.
Direct
These small electric boilers heat water as needed rather than storing hot water. Therefore, there is a slight delay in hot water reaching the tap. However, its benefits include a lower cost to buy and install and needs less space.
Storage
These provide hot water as needed and store a reservoir of hot water so you can use Economy 7 tariff during the night. However, these cost more to buy and take up more space because they include a tank.
CPSU
Standing for ‘Combined Primary Storage Tanks’, these meet high demands by storing a lot of hot water. These are very large and use a lot of space. Therefore, they’re better suited to a large home with more than two bathrooms.
Dry Core
These boilers use Economy 7 during the night to store heat in bricks, which transfer the heat to stored water. These boilers are cost–effective, but they’re better suited to smaller homes with less demand for hot water.
Solar compatible
These are boilers that use solar panels during the day to heat water and a low-cost Economy 7 immersion heater during the night.
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Electric Combi Boiler Models
Many companies produce differently sized combi units suitable for various applications. Most professional heating engineers in the UK recommend the following electric boiler companies.
Electric Combo Boilers Co.
The Elektra boiler has a 2 to 12kW output. Also, it has a 2-year warranty and costs about £1190.
EHC
The Comet boiler comes in 9, 12, and 14kW models. Also, it has a 2-year warranty on the boiler and a 5-year warranty on the cylinder. It costs around £2570.
Elnur
The Mattira MAC15 boiler comes in 3 to 15kW models, with a 2-year warranty on the boiler and 5 years on cylinder. This one costs between £1750 and £2000.
Heatrae Sadia
The Electromax comes as a 6kWh or 9kW model. It comes with a 2-year warranty and 10 years on the cylinder. It costs between £1800 and £2000.
Energy Efficiency
Electric combi boilers have greater efficiency than other types (about 99% efficient) because they don’t burn fuel such as oil or gas. Electrical energy isn’t wasted and you only pay for what you use.
Compare these with other fuel types and we have gas boilers that use about 90 to 95% of the energy they produce. While oil-fired boilers use 85% t 95%.
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Electric boiler running costs
As a general rule, electric combi boilers have higher fuel costs than others, because daytime electricity costs are more expensive than oil or gas. Although fuel costs change regularly and vary depending on your supplier, oil will cost you around 5p/kWh while gas costs about 4.2p/kWh.
Economy 7 tariffs give night-time electricity charges of about 6p to 8p/kWh. But, daytime rates on the same tariff will be about 16p/kWh. You can see that night-time rates compare favourably with oil and gas prices. Especially, when you take into account the lower installation and maintenance costs of electric boilers, together with the better water heating efficiency. Electric boilers cost much less to install than gas or oil–fired boilers and don’t need the regular maintenance checks and the annual gas safety certificate costing about £75 per year.
In fact, the average running costs of a unit of electricity on Economy 7 works out at about £1000 per year cheaper than otherwise.
| Radiators | Power used (BTU) | Power (kWh) | Average cost per annum |
|---|---|---|---|
| 2 | 13,600 | 4 | £1,500 |
| 5 | 20,500 | 6 | £1,650 |
| 9 | 30,700 | 9 | £1,800 |
| 11 | 38,000 | 11 | £2,000 |
| 12 | 41,000 | 12 | £2,100 |
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Electricity tariffs
Although electricity is clean and less wasteful, it is expensive. So, the providers offer discounted rates at certain times of the day to encourage use.
Economy 7 tariffs charge discounted rates for 7 hours throughout the night, to encourage consumers to use electricity and store heat at when electricity demand is less. But, at the same time, they charge more for daytime power consumption. The cost of each tariff depends on the supplier and what contract you are tied to. But, if your lifestyle allows you to use more electricity at night than during the day, it can work out much cheaper for you.
Economy 10 is a different type of tariff. You receive 10 hours of electricity at the discounted rate. But, the hours are split so you receive 3 hours low rate in the afternoon, 4 hours in the evening, and 3 hours in the early morning. The ‘off-peak’ hours are when the provider specifies, but it’s possible to live a more ‘normal’ life using economy 10.
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Electric Boiler Benefits
An electric hot water boiler has many benefits compared to other central heating types.
Relatively small size
Although they come in many sizes depending on the power output and their function, electric combi boilers are generally smaller than their equivalent using other fuels. Also, they don’t need flues for exhaust gases or any special ventilation requirements. Usually, they will easily fit in a standard kitchen unit or under the stairs. You don’t have to worry about carbon monoxide build-up or about having a monitor. There’s no need to have storage tanks like oil–fired boilers or have gas pipes running through the house.
Quiet
Gas and oil boilers usually emit a low hum when working. Whereas, electric boilers make no noise at all, even when heating water.
Ease of use
Electric combi boilers are very easy to use. They have a digital display with a temperature reading, and a control knob to turn the heat up or down. You will also need a way to programme ON/OFF times throughout the day for central heating. Alternatively, these days you can connect the smart thermostat to the house’s Smart Hub.
Cost–effective
They are very easy to install by a professional and need fewer regular maintenance visits. Therefore, they cost less in labour charges.
Low maintenance
Electric combi boilers have fewer moving parts. So, will need fewer repairs and less maintenance.
Future proof
The world’s oil and gas resources will run out in the next 50 years or so. However, we can generate electricity from many different sources, such as hydroelectric, wind, solar, biomass, or nuclear.
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Electric Combi Boiler Disadvantages
Electric combi boilers aren’t all good news. There are disadvantages too.
Higher running costs
At present, electrical energy costs more than oil or gas unless you own a photovoltaic solar generator. Therefore, electricity bills will be significantly higher than those of other fuels. You can use the Economy 7 tariff at night time. But, beware, you’ll have much higher daytime rates.
Less hot water
Electric combi boilers heat water as you need it. This means that it might take a while for the hot water to reach the hot tap. They are, therefore, better for use in smaller homes with lower hot water demand. However, if you have a larger house with many hot water outlets, it might be worthwhile using gas or oil.
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Electric Boiler FAQ
How long does an electric boiler last?
An electric boiler lasts from between 10 to 15 years if you have it regularly maintained.
Are electric boilers cheaper than gas?
Electric boilers are more efficient, more compact, and easier to install than a gas system. But, a unit of electricity costs around 3 times the price of a unit of gas. So, although the boilers cost less to buy and install, they cost more to heat water.
Can I replace my gas boiler with an electric boiler?
Yes, you definitely can. And, an old oil boiler too. There are advantages to encourage you to make the change. Electricity is cleaner, has no exhaust gases so doesn’t need a flue or a continuous air ventilation supply, and you use a more compact boiler.
Do you need a water tank with an electric combi boiler?
No. The big advantage with combi boilers is that they heat water on demand so you don’t need a storage tank to store the hot water until needed. Usually, a combi will fit easily into a kitchen unit, on the wall or under the stairs.
Should I leave the heating on all day or only turn it on when needed?
Although a combi boiler only gives hot water on demand, it heats your central heating to the required temperature when it’s programmed to. The Energy Saving Trust advises us to turn on the central heating only when you need it and not leave it on low setting all day. Otherwise, you’re losing heat throughout the day, rather than just part of the day.
Are electric boilers reliable?
Definitely. They have less mechanical parts than other types of water heater, so need less maintenance and repair visits. And, because you aren’t burning fuel in your home, you need fewer safety checks too. However, they are just as reliable, if not more, than gas or oil boilers.
Do you need a cylinder with an electric boiler?
No, you don’t need a cylinder with an electric combi boiler. However, a system boiler does need one. Similarly, if you have a property with a bathtub rather than a shower, you will probably need to store hot water in which case you will need a storage boiler.
Do electric boilers need a water tank?
Electric combi boilers come in a variety of sizes. The small ones just produce hot water on demand and don’t need a storage cylinder or a header tank. However, a storage electric boiler has an in-built hot water tank or connects to a separate one. This means you can heat the water overnight using cheaper tariffs.
Electric combi boiler review
Switching to an electric boiler from gas or oil might cost you more in the short term with higher fuel costs. However, there are cheaper electricity tariffs available to reduce the utility bills. And, the long term repair, maintenance and inspection costs will be less too. Looking further ahead into the future, oil and gas will eventually run out, but electricity can be generated from a variety of methods.
If you want to find out about electric combi boiler costs for your house, complete the form on this page. Then, you will receive 3 or 4 quotes from heating engineers near you.
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