Households with combi boilers could reduce their annual energy costs by around £57 simply by adjusting the flow temperature dial, according to research from the foundation Nesta. The organisation found that many boilers heat radiator water to temperatures far higher than necessary, wasting energy in the process.
Condensing combi boilers are often set to send water to radiators at 75C or 80C, but Nesta calculates that lowering this to 60C could cut a household's total gas consumption by roughly 7%. This adjustment costs nothing to check and could deliver average annual savings of about £57.
Understanding boiler flow temperature
The flow temperature is how hot the boiler makes the water before pumping it to the radiators. As the water circulates, it cools down and returns to the boiler at a lower temperature, known as the return temperature.
For households with a combi boiler and no hot water cylinder, the Energy Saving Trust advises that there will be two dials or controls - one for the radiators and one for hot water. The radiator control, which may be marked with a radiator icon rather than a tap symbol, is the one to adjust.
How to adjust the setting safely
Experts recommend taking a photo or noting the current settings before making any changes, so you can revert if needed. They add that in mild weather, a lower flow temperature of around 50 or 55 degrees may be sufficient to heat the home, while colder conditions may require a higher setting.
Adjusting the flow temperature to 60C is a simple step that could reduce gas consumption and lower annual bills without upfront cost.
