Octopus Energy published boiler flow temperature guidance

Octopus Energy has published guidance telling households to set the flow temperature on a combi boiler to between 55 and 60 degrees, according to a report on the supplier's tips published on 5 October 2026¹. The guidance points readers to Nesta's Money Saving Boiler walkthrough, and the saving is put at "up to £65" depending on the boiler¹.

The figure differs from Nesta's own estimate. Nesta, a research and innovation foundation, says almost 8 million UK households could each save £57 by lowering combi boiler flow temperature, based on a reanalysis of the 2022 Salford Energy House experiment carried out in June and July 2026 and priced at the September to December 2026 gas unit rate of 7.97p per kWh². Nesta estimates that reducing flow temperature from 75C to 60C cuts overall gas consumption by about 7%, or 720 kWh a year for a household using 9,876 kWh of gas annually². It adds that the estimate assumes longer heating-up times, which depend on radiator sizes and the heating system².

Octopus's guidance sits within a list of 10 tips that the supplier says could save "up to £517" in total¹. The other items and their stated savings are below.

Source: Octopus Energy tips as reported¹.

Boiler flow temperatures are usually set by default at 75 to 80C, which stops condensing boilers running at peak efficiency¹. Octopus's guidance, as reported, says radiators may feel cooler after the change and rooms may take slightly longer to heat, which it describes as expected and says can be addressed by setting the heating to start 15 to 30 minutes earlier¹. The Energy Saving Trust says settings should be adjusted gradually and that finding the right level may involve some trial and error¹. Guidance attributed to the Trust also notes that a combi boiler without a hot water cylinder has two controls, one for radiators and one for hot water, and that mild weather may allow a lower flow temperature of 50 or 55 degrees³.

"When bills are biting, every penny counts. We need to get homes off expensive, unpredictable gas and onto cheaper electric heating - but in the meantime, there are simple ways to make the heating you've got work harder for your money."

Why it matters for households

Flow temperature is a setting on the boiler itself rather than a change of tariff, supplier or equipment, so the saving, where it materialises, comes from using less gas for the same rooms. For a gas-heated home that is a reduction in the fuel bill rather than a step towards energy independence: the household still relies on the gas network, and the size of the gain depends on the boiler, the radiators and how the heating is controlled². Nesta's £57 figure is an average across homes it judges suitable for the change, not a guarantee for any one property². The gap between Nesta's £57 and the "up to £65" cited in Octopus's guidance has not been explained in the reported material².

What happens next

Nesta published its research on 22 October 2026 and is promoting its Money Saving Boiler Challenge tool, which it says has helped 3.1 million households save almost £300 million since 2022². It estimates that a further 1 million households lowering flow temperature would add £57 million to savings, or £220 million if all six of its free measures were taken up by April². The campaign is supported by Which?, British Gas, NRLA, Octopus, Heating Hub, Energy UK, OVO and EDF². The reported guidance also notes that the Ofgem price cap is due to climb further in January after the 1 October rise¹.

Sources4 sources

1. Octopus Energy boiler check could save UK homeowners 'up to £65' - The Mirror, mirror.co.uk
2. Millions of households missing out on nearly £60 of energy savings | Nesta, nesta.org.uk
3. Two second boiler check could take £57 off energy bills | Personal Finance | Finance | Express.co.uk, express.co.uk
4. Exact temperature to set combi boiler to slash energy bills - The Mirror, mirror.co.uk