Adjusting a simple boiler setting can help keep your home cooler during hot weather and reduce energy bills, according to gas safety experts. Patrick Garner, a Gas Safe registered engineer at Heatable, explains that many households unknowingly waste energy and generate excess heat through their combi boiler's hot water settings, even when the heating is turned off.
Why Your Home May Be Hotter Than Necessary
Homes with gas combi boilers can still produce heat even with the heating switched off due to the hot water function. Every time you shower, run a hot tap, or wash dishes, the boiler fires up. Although each burst is brief, the boiler releases heat through its casing, pipework, and flue, contributing to the overall warmth in your home and consuming gas continuously.
"Once the heating is off, hot water becomes the main thing still using gas," said Garner. "And in homes with several people showering every day, the cost soon adds up."
Key Boiler Settings to Adjust
First, ensure your boiler is set to hot-water-only mode. Leaving both heating and hot water enabled could cause the heating to activate unexpectedly if the temperature drops or a thermostat is poorly positioned.
Second, check the hot water temperature setting on the boiler. For combi boilers, a range of 45°C to 50°C is typically sufficient for taps and showers. "Importantly, this only applies to combi boilers," Garner warned. "If your home has a hot water cylinder, do not reduce the stored water temperature below 60°C to avoid the risk of Legionella."
Finally, disable the pre-heat or comfort mode if your boiler has it. This function keeps a small amount of water warm inside the boiler to deliver hot water faster, but it causes the boiler to cycle on and off throughout the day, even when no hot water is being used. "Pre-heat mode constantly adds heat to your home and inflates your bills," Garner added.
Additional Cost-Cutting Tips
Other simple changes can further reduce energy consumption. Leaving washing up until you can do one large load at the end of the day eliminates short heating cycles that increase bills. Repairing any dripping hot taps can lower both gas and water bills. Avoid unnecessary upgrades like solar diverters unless you already have solar panels, a hot water cylinder, and an immersion heater; they are not suitable for standard combi boilers.
"You pay a standing charge of around 30p a day for being connected to the gas network, so you'll never get your bill down to zero," Garner said. "But a few changes can make a big difference overall."
