Is it cheaper to run an electric boiler or a gas boiler?
In most UK homes, a gas boiler is usually cheaper to run than a direct electric boiler because gas normally costs less per unit of energy than electricity. Electric boilers are very efficient at the point of use, but the higher price of electricity often makes the total running cost higher.
However there are ways to reduce the cost of using an electric boiler
You can reduce the running cost of an electric boiler by using thermal storage, but it is important to understand that it does not make the boiler more efficient. A direct electric boiler is already close to 100% efficient at the point of use. What thermal storage does is allow you to buy electricity at a cheaper time, usually overnight, and store that heat for use during the day.
The usual approach is to install a large, well-insulated thermal store or buffer tank. The electric boiler heats the stored water overnight using an off-peak tariff such as Economy 7, Economy 10, or a smart time-of-use tariff. Ofgem says that Economy 7 can help customers save money when they use more electricity at night. According to the Energy Saving Trust, dual-rate tariffs provide cheaper electricity during specific overnight hours.
During the day, the heating system then draws heat from the thermal store instead of running the electric boiler on the more expensive daytime rate. This approach can be useful for underfloor heating, radiators, fan convectors, or domestic hot water preheating, depending on the system design.
To make this work properly, the thermal store needs to be large enough for the heat demand. This requirement is especially important in larger homes or commercial buildings. If the store is too small, the electric boiler will still need to run during the day at peak-rate electricity, reducing the saving.
Effective controls are essential. The system should prioritise charging the store during the cheapest electricity period, prevent unnecessary daytime top-ups, and use weather compensation or lower flow temperatures where possible. The lower the heating flow temperature, the longer the stored heat will last.
You can also improve the economics by combining the electric boiler and thermal store with solar PV, an immersion diverter, or battery storage. Fabric upgrades such as loft insulation, wall insulation, draught-proofing and better heating controls are also important because reducing heat loss reduces the size of the store and amount of electricity needed.
However, thermal storage does have limits. A large store takes up space, has standing heat losses, and must be carefully sized.
In simple terms, thermal storage helps by shifting electric boiler operation to cheaper off-peak electricity, rather than removing the cost completely.
A gas boiler may waste some heat through the flue, but the lower fuel cost can still make it cheaper overall. This is why gas boilers are still commonly used in larger homes or properties with higher heating demand.
However, the best option depends on the building. Electric boilers can make sense in small, well-insulated homes, flats, occasional-use buildings, extensions, offices, or properties without a gas supply. They may also be easier and cheaper to install because they do not need a flue, gas pipe, oil tank, or fuel storage.
For larger or poorly insulated homes, gas boilers or heat pumps are often cheaper to run. The correct choice depends on insulation, heating demand, electricity tariff, hot water usage, and installation cost.
For more detailed information on our electric boilers, please see the following webpage – Electric boiler system
