Little-Known Boiler Setting Could Be Wasting Hundreds on Heating, Expert Warns

Households are being urged to check a simple setting on their combi boiler, as many across the UK could be spending far more than necessary to heat their homes this winter.

With colder weather increasing heating use, energy bills are already expected to rise again in the new year. But experts say a common mistake with boiler temperature settings means many families are wasting money without realising.

Most modern homes have a condensing combi boiler designed to run efficiently at lower flow temperatures. However, many are still set much higher by default, often between 70°C and 80°C.

Gordon Wallis, energy expert at Your NRG, explained that adjusting the boiler’s flow temperature could help reduce gas usage without turning the heating off.

He said: “If your boiler’s flow temperature is set too high, your system will burn more gas than it needs to heat your radiators. By lowering the radiator flow temperature to around 55°C or 60°C, you can often heat your home just as effectively while using less energy.”

The flow temperature controls how hot the water leaving the boiler is, which then circulates around radiators. Crucially, this is not the same as turning down your thermostat.

Wallis added: “It will not make your house colder, but it may take radiators slightly longer to heat up. Once they are warm, the home will feel the same, but you will be using less fuel to get there.”

Social media advice has recently highlighted the issue, with many energy suppliers also recommending lower flow temperatures for better boiler efficiency.

However, Wallis warns that this change is most effective for homes with combi boilers and reasonably well-insulated properties.

He said: “If you have a hot water tank system or an older boiler, do check with a qualified engineer first. But for most modern combi boilers, this is a very simple and effective adjustment that households can make themselves.”

Households are also advised to check their hot water temperature setting, as this is often set unnecessarily high.

Wallis said: “If your tap water is so hot that you have to add cold water to use it, you are paying for heat you do not need.”

With energy costs still a major concern this winter, simple boiler efficiency steps could help reduce bills without sacrificing warmth.

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