What are the disadvantages of an electric combi boiler?

What are the disadvantages of an electric combi boiler? The biggest downside of an electric combi boiler is that it might struggle to supply large amounts of household hot water compared with a gas combi boiler. This is because the power supply to the property restricts the size of the electric boiler you can use. Many UK houses may not be able to sustain a very high-output electric combi boiler due to the incoming electrical supply, especially if other high-load appliances are being used at the same time.

Another downside is the running costs. Electric boilers are particularly efficient (99.9%) at the point of use (almost all the power is converted to heat), but electricity is normally pricier per kWh than mains gas. This makes an electric combi boiler pricier to run, especially in larger homes, poorly insulated premises or buildings with a high heating demand.

Hot water flow rate could potentially be a limiting factor. A small electric combi boiler may be fine for a kitchen sink, basin or single shower but not so good for many bathrooms or if hot water outlets are used at the same time. In certain instances, an electric system boiler with an indirect unvented cylinder may be more appropriate.

Larger electric combi boilers (anything over 15kW of output) will require a three-phase electrical supply to operate. Our full range is detailed here – Flexiheat electric combination boilers

They are suitable for small, well-insulated houses with low hot water requirements. Larger houses, business buildings or those with significant hot water demand may find electric combi-boilers less viable due to their limited hot-water performance.