Skip to main content

Electric heating systems

05/06/2021

Chris Allen

Electric Heating Company

Chris poses the question is electric heating a low carbon option for my home?

Is electric heating a low carbon option for my home?

Electric boilers are clean, quiet and can run on 100% renewable energy, but they can also be costly to run and not always the right solution for hot water. Chris Allan of the Electric Heating Company gives a consumer guide to when electric heating is the right solution for you, what you’ll need to check before you buy one and their role in the future of domestic heat.

Contents

  1. What’s making you think about going electric?
  2. When an electric boiler is right for you
  3. When an electric boiler is wrong for you
  4. How can I reduce my electricity costs?
  5. An electric boiler seems right for me, what’s next?
  6. The role of the electric boiler in the future of heat

1) What’s making you think about going electric?

There are many reasons you may be considering an electric boiler: 

  • Gas boilers can be difficult to position as they require a flue to outside and pipework to a drain. Flats are often particularly tricky in this respect, particularly when they are high up.
  • For those off-grid, the presence of a fuel tank in your garden is often not desirable or possible.
  • Oil fuel lines can give rise to blockages that stop the boiler working, reducing reliability.
  • Many households simply want to move away from fossil fuel heating systems.

Customers are increasingly looking for cleaner, greener and more reliable alternatives. An electric boiler can solve all of these problems, but they are not a blanket solution for all households because running costs per kWh (kiloWatt hour) are currently much higher.

2) When an electric boiler is right for you:

As a company we are very careful not to sell electric boilers to customers where they are not the right solution. An electric boiler is suitable in very particular circumstances, namely:

  • Modern homes with low heat requirements
  • Flats where the heat demand is lower due to property size
  • Homes with solar PV panels and/or battery storage - but it will be on a case-by-case basis.
  • Off-grid homes that cannot have a bulk oil or LPG tank and would have to use small gas bottles

When they are right, electric boilers offer many clear benefits:

  • Safer – no risk of gas leaks or oil spills because electric boilers do not burn fuel
  • Cheaper to fit – no gas pipe, oil line, on site storage costs, flue or draining required.
  • Easier to fit – can be located anywhere in the home
  • Cleaner – electric boilers do not produce any local emissions as gas and oil boilers do
  • Renewable – if run on 100% renewable electric sources
  • 100% efficient – unlike gas and oil boilers no fuel is wasted

3) When an electric boiler is wrong for you:

When they are wrong, they can be too expensive to run. An average 2 bed UK home consumes around 7,500kWh of energy for heating and hot water per year (based on studies carried out by us). This would cost £1,125 per annum using electricity based on 15p per kWh compared with around £460 per annum for the same consumption of gas at 4p per kWh and accounting for inefficiencies. (Due to most gas boilers being grossly over sized and poorly set up, our studies have found that the actual consumption of gas for an identical property with gas boiler is around 11,500kWh.)

As a guide higher running costs will be experienced in older properties which have little or no insulation compared to well insulated properties. Electric boilers are also not always suited to larger 5 bed+ properties due to the higher kW capacity required to heat the property (unless 3 phase power is available).

Homes with a bath or large hot water demand will require a hot water cylinder to build up a store of hot water. Depending on the size of the cylinder and size of the coil used to heat the cylinder by the boiler, an electric boiler can be slower to re-heat the cylinder than a gas or oil boiler. This is because gas and oil boilers can provide 15-40kW of power to re-heat cylinders quickly whereas standard electric boilers provide a maximum of 14.4kW.

Households will have a similar re-heat time if they currently use a copper cylinder with foam insulation cover, but a slower re-heat time if they have an unvented hot water cylinder. Unvented cylinders re-heat much faster because they have a coil that can provide 20-30kW of power when re-heating.

4) How can I reduce my electricity costs?

There are number of innovative ways to reduce electricity costs, as follows:

  • A number of electricity suppliers offer off-peak tariffs that can be utilised during set hours of the day and night to boost the heating & hot water systems during the lower rates. Other appliances can also be programmed to come on during off-peak tariffs, such as washing machines and dish washers, likewise electric vehicle charging.
  • Solar PV panels often produce a surplus of energy that is exported back to the grid. This surplus can be better utilised by an electric heating system to further reduce carbon emissions and lower energy costs. One option is to combine the solar PV with ‘trickle feeding PV radiators’ to create background heat turning the property into a heat battery
  • For some homes battery storage will also be appropriate and this presents opportunities to charge the battery overnight on off-peak tariffs and supply your home through the day (along with the solar PV) panels at a much lower cost per kWh.

5) Electric heating seems right for me, what next?

If an electric boiler is right for you, the first step is to it is get an electrician to carry out a ‘load’ check. All homes have a limited amount of electricity supply, usually 60, 80 or 100 amps. Each household appliance will require some of those amps. Some appliances run all the time, like fridges, others come on and off and temporarily increase the number amps used, such as a kettle or electric shower.

As a rule, your home needs 40 amps spare after heating. Depending on your spare capacity, some high load appliances such as electric showers, instantaneous electric water heaters and hot tubs, will not be able to operate at the same time as the electric boiler. Extra controls can be fitted that will shut the boiler down temporarily whilst these appliances are in operation.

Do I have enough spare amps?

A 6kW boiler consumes 32amps, 9kW boiler needs 39 amps, 12kW boiler needs 52 amps and 14.4kW boiler need 63amps. An electrician can tell you how much your supply gives you and how much you have left over for an electric boiler. If you are fitting one of the larger models you will definitely need to upgrade to 100amp supply.

Can I increase the number of amps I have? Your electricity distributor, known as a DNO (Distribution Network Operator), will usually let you go one higher, i.e. if you have 60amps you can go to 80amps and if you have 80amps you can go to 100amps. You can contact your regional DNO to arrange a visit. To find out who your DNO is visit https://www.energynetworks.org/operating-the-networks/whos-my-network-operator

What size boiler will I need?

The good news is that you will not need a big boiler. Whilst 6-14.4kW boilers sound very small, the vast majority of modern homes need 6-12kW so the three smallest boilers in our range would cover most suitable properties. Getting the heat demand right is important as it can mean fitting a smaller model, although larger models to help with hot water re-heat times.

What type of electric boiler should I have?

Electric boilers usually work with a hot water cylinder in the same way as a gas or oil boiler, i.e. the boiler will heat the home directly via radiators and the hot water via a coil in the cylinder. Combi electric boilers are also available but have a limited application. As they can only supply at best 6 litres per minute they are only really suited to small one-bathroom properties with a sink, basin and a standard shower head.

Whilst some ‘storage combis’ have been developed that can offer higher flow rates, that is only for the period that the store of hot water is available. A storage combi is basically a boiler combined with a small hot water cylinder that can supplement your flow rates of the hot water but only until the cylinder is depleted. Once depleted the boiler will return to providing 3-6 litres per minute.

6) The role of the electric boiler in the future of domestic heat

The future of domestic heating is going to be largely electric. Electricity can be generated by renewable sources (such as wind and solar farms) via power stations or on our roofs. As we move away from fossil fuels, electric powered heating systems will be the main replacement.

Heat pumps have been identified as the primary technology, however they are bulky and not suitable for all properties. Electric boilers have been identified as having a roll to play in decarbonising homes. The cost of electricity remains the main barrier to take up, but it is anticipated that electricity costs will have to be subsidised to encourage take up in the long term.