Secret boiler hack that can slash £65 off your energy bills this winter

Customers with combi boilers are being encouraged to check their heating flow temperature and consider lowering it to between 55 and 60 degrees Celsius.

This setting controls how hot the water gets before it travels from the boiler to the radiators.

Most combi boilers leave the factory with flow temperatures set between 70 and 80 degrees Celsius. Installers often leave these settings unchanged, meaning some households could be using more gas than necessary.

Octopus included the adjustment among its winter money-saving tips and directed customers to a free online guide from innovation agency Nesta.

The walkthrough explains how to change the setting based on the type of boiler display.

Reducing the flow temperature can help a boiler recover more heat that would otherwise escape, allowing it to warm the home using less gas.

Nesta said that operating in “condensing mode” means the boiler “will recover heat that would otherwise be lost and will run more efficiently”.

Combi boilers work most efficiently when heating radiators to 60 degrees Celsius or below, according to Octopus.

However, radiators may feel slightly cooler after the adjustment, and rooms could take longer to warm up. This is normal, according to Nesta.

Setting the heating to come on 15 to 30 minutes earlier can allow extra time for rooms to reach a comfortable temperature.

Finding the best setting for a property may take a few adjustments.

The Energy Saving Trust recommends that homeowners “should adjust settings gradually and make sure your heating controls are set up correctly before making changes”.

It added that finding the right balance may involve “some trial-and-error”.

Octopus also highlighted the preheat feature found on some combi boilers, which keeps water ready for use even when the hot taps are off.

Switching this feature off can reduce gas use further, although it is separate from adjusting the radiator flow temperature.

The adjustment can be made directly through the boiler’s control panel, and the change is entirely reversible if needed.

Beyond the boiler adjustment, Octopus Energy shared a range of further tips for reducing household energy costs.

The biggest potential saving comes from managing the thermostat more carefully, which could trim bills by £90.

Draught-proofing gaps around the home could knock off £85, while air-drying clothes instead of using a tumble dryer could save £50.

Turning off devices left on standby could cut £45, as could reducing shower time and switching to energy-efficient lighting. Fitting an insulation jacket on a hot water tank could save £40.

Smaller but still worthwhile measures include washing clothes less frequently and at 30 degrees Celsius, saving £27, and swapping to a more efficient shower head, worth around £25.

Octopus Energy has also confirmed it is once again handing out electric blankets to its most vulnerable customers. The company said it exists to “support customers most in need, particularly people with really specific vulnerabilities and medical needs”.

The scheme began after one of the firm’s engineers calculated that heating an entire home costs roughly £4 a day, whereas an energy-efficient electric blanket can warm a person for just two to four pence an hour.

The blankets cost approximately £50 but could save a typical household around £300 compared with leaving the heating running constantly, according to the company’s research.

Octopus said it was “prioritising those customers” with specific needs and encouraged anyone else to consider buying a blanket independently. Those wishing to apply should do so through the Octo Assist fund, with decisions typically made within a week.