The main advantage that modern boilers have over their elderly counterparts is that they are all condensing boilers. A well-maintained older boiler will still burn its fuel very efficiently, but it’ll inevitably lose heat in the hot gases that escape up the flue. In contrast, a condensing boiler has a bigger heat exchanger, recovering more heat, sending 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 (giving the boiler its name). When this happens, even more energy is recovered from the condensing vapour, and the efficiency gets higher still.


  • Your boiler accounts for around 60% of your annual energy bill
  • Replacing a G rated boiler with an A rated boiler could save you more than £300 per year*
  • Condensing boilers are about 90% efficient – so 90% of the energy used in the gas is converted into heating or hot water for your home.


Replacing your boiler is a sensible investment for anyone to make. Your boiler accounts for about 60% of what you spend on energy bills each year so having an efficient boiler is very important.

Many people may view this as an unnecessary expense but, with energy prices on the rise, the more efficient your heating system is, the more control you’ll have over your energy costs.

Boilers are rated A – G, with A being the most energy efficient and G being the least energy efficient. Replacing an old G-rated gas boiler with an A-rated, high efficiency condensing boiler could make a huge difference to your energy bills, potentially saving as much as £300 every year.


To make sure they’re safe and energy efficient boilers need to be serviced annually. Regular services are vital for checking that boilers are working correctly and ensure that the manufacturers warranty stays valid.


Mark Group offer a wide range of boilers and heating systems, all designed to suit your individual needs, with prices starting from as little as £1,799* for a boiler replacement, allowing you to reap the benefits of a more efficient heating system.It all depends on how old and inefficient your old boiler is but the following figures** demonstrate the approximate saving when replacing your old boiler for an A-rated condensing boiler:


* Subject to survey
**Source: Energy Saving Trust, 2013 based on a gas heated, semi-detached home with three bedrooms.