How efficient are electric boilers?

How efficient are electric boilers? Well, the answer is at point of use, electric boilers are 100% energy efficient at the immersion heaters, turning all of the electricity they consume into usable heat.

Could you please explain why they are sometimes quoted as being 99% to 100% energy efficient?

Although virtually all the electrical energy consumed is converted directly into heat through resistance heating (similar to a kettle), some argue that the overall efficiency is 99% because the boiler control panel uses a small amount of electricity during operation or standby mode, which does not contribute to heat output.

How do electric and gas boilers compare for energy efficiency?

Alternatives such as gas boilers are not and never will be 100 per cent efficient, not even a condensing gas boiler. A condensing gas boiler with an A+ energy rating will typically have an energy efficiency in the range of 92%–95%.

The heating system return water temperature must be under ≤ 55°C (ideally ≤ 40–50°C) for a gas boiler to condense optimally.

The efficiency of gas boilers older than 25 years can drop below 60% or even lower, as the heat exchanger becomes fouled up (something that doesn’t happen with electric boilers). Low efficiency results in a loss of both energy and wasted money, whilst electric boiler efficiency will always be 100%.

Dirty heat exchangers reduce condensation and the efficiency of gas boilers. That’s why they should be serviced annually, as well as to check for a gas leak, carbon monoxide leak, etc.

Ultimately, natural gas, or even LPG (propane) gas, are both derived from fossil fuels.

What is the situation with oil boilers?

A condensing oil boiler, when run with return temperatures lower than ≤ 50°C for full condensing operation (low-temperature operation, e.g., underfloor heating or oversized radiators), is between 92% and 96% energy efficient. But you’re also burning fossil fuels, which have a sulphur content that must be treated to avoid acidic condensate corrosion and ensure the longevity of the boiler.

Electric boiler pros

Electric boilers are 100% efficient on the immersion heaters, regardless of the flow and return temperatures—whether low or high—because the heating element simply draws power and heats water until the thermostat for the central heating system is satisfied.

The system produces no flue gases. There are no combustion losses. No latent heat to recover. No condensation is needed with an electric boiler installation as opposed to gas and oil boilers.

Electric boilers tend to be combined with an indirect unvented cylinder for domestic hot water production; the electric central heating boilers are detailed on this webpage – Electric central heating boilers 

and please see this webpage – for the indirect unvented cylinders, for the DHW production.

We also offer a range of electric combi boilers designed for central heating and instant domestic hot water needs, eliminating the requirement for a hot water cylinder; further details can be found on this webpage – Electric combi boilers

Electric boiler running costs

Renewable energy sources such as wind turbines, solar panels, and tidal or hydropower systems can not only reduce your carbon emissions and thus carbon footprint. They can also reduce the electric boiler running costs if you’re generating electricity yourself.

Contact Flexiheat UK

Hopefully the above has answered your “How efficient are electric boilers?” or “are electric boilers efficient?” question; however, should you have any further questions, please don’t hesitate to contact our Flexiheat UK sales team on 01202 822221 or click here for our email contact form.