Worried about fuel bills ? Check your boiler this autumn to avoid wasting fuel!

Together, the three suggestions below can save you 20% or more off your home energy bills, or about £500 for an average home. So, they are good for the wallet and good for the planet, without you feeling colder.

1. Replace an old boiler

First, how old is your boiler ? There are two reasons to replace any boiler over 15 years old. First, it’s likely to be an older design, not an efficient condensing boiler. Second, oil and gas are corrosive and erode the heat exchanger, reducing boiler efficiency over time. The result is that upgrading a 20 or 30 year old boiler to a new condensing boiler can cut your energy bills by 30%.

An alternative is to use the £7500 government grant to install a heat pump, which is much greener and more efficient as it uses renewable electricity.

2. Switch to eco mode

Our second suggestion is specific to oil and gas combi boilers. All combi boilers have a preheat “comfort” function which heats about five litres of water in the boiler to reduce the delay for hot water arriving at the tap. While convenient, this means the boiler comes on all day, even when heating is off in the summer. Over the year this uses a significant amount of fuel, so turning preheating off can save you 10% on energy bills. 

Unfortunately, it can be hard to check if your combi boiler is in preheat mode or fuel-saving Eco mode. Some boilers have an Eco button; a green light appears when Eco mode is on. You will have to check the boiler manual or online to discover which mode your boiler is in, and how to change it.

The slightly increased water use caused by waiting 10-15 seconds longer for hot water is very unlikely to outweigh your energy savings. Note that a power cut, switching your boiler off or other electricity interruption causes some combi boilers to come back on in preheat or comfort mode, not in Eco mode – even if you had activated this ! So, check occasionally that Eco mode is still on, especially after power cuts.

3. Turn the radiator heating temperature down

Our final suggestion applies to all condensing boilers (oil and gas, combi and normal "system" boilers). If the radiator heating temperature dial on the boiler is set above 65C, the boiler is not working in the efficient condensing range, wasting 10-15% of the energy it uses. To stop this waste, reduce the radiator heating temperature to between 50C and 60C. This means your radiators will be cooler, so your house will take slightly longer to warm up. Try to find the right balance for you by experimenting with different radiator temperatures and timings for your heating.