Heating accounts for around 60% of what you spend a year on energy bills, so an efficient boiler makes a big difference.
Modern boilers are more efficient for several reasons, but their main advantage is that they are all condensing boilers. All well maintained boilers burn their fuel very efficiently, but they inevitably lose some heat in the hot gases that escape up the flue. A condensing boiler has a large heat exchanger, so it recovers more heat, sends cooler gases up the flue and is more efficient.
Sometimes the flue gases get so cool that the water vapour in the gas condenses out and even more energy is recovered from the condensing vapour.
How much you can save will depend on how old and inefficient your existing boiler is and the fuel your boiler uses. Below are some examples of potential savings for a home heated by gas central heating.
Upgrading an old gas boiler with a programmer and room thermostat, with a new A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator controls (TRVs) could save you:
Old boiler rating
Mid terrace house
Mid floor flat
These are estimated figures based on installing a new A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator controls (TRVs) in a gas-heated home from an older boiler with a programmer and room thermostat. Savings will vary depending on the size and thermal performance of your home. Figures are based on fuel prices as of March 2016.