When the Building Regulations changed in 2005, it became a requirement that all boilers installed were condensing, or high efficiency, boilers.  Replacing an old non-condensing, also known as standard efficiency or regular, boiler will save money on heating bills and reduce the carbon dioxide emissions that contribute to global warming.

The difference between an old non-condensing boiler and a new condensing model is the amount of useable heat it produces from the fuel it burns. Old boilers usually have a pilot light, which is burning all the time, whether the boiler is heating hot or not.  When the boiler turns on, it burns fuel in a combustion chamber which is surrounded by a jacket through which the water flows, and this heated water is circulated around the radiators to warm the home. Some of the heat generated in the boiler is lost to the surrounding air and through the flue.  A non-condensing boiler could be as little as 60 per cent efficient, meaning for every pound spent on gas, 40p is lost.

A condensing boiler is much more efficient at heating your home. It has a much larger heat exchanger, which extracts over 90 per cent of the heat from the fuel it burns, making it much more cost effective to run. It extracts the heat from the flue gases, which would otherwise be lost to the atmosphere, and recycles the heat back into the heating system. The water vapour in the flue gases can be so cool that it condenses (hence the name!), and is taken away to a waste pipe through a condensate pipe. Condensing boilers do not need a pilot light burning all the time, because they fire up when there is a demand for heat, using an electric spark.

The amount you save installing a new condensing boiler will depend on how old and inefficient your existing boiler is.

Combi (or combination) boilers are the UK’s most popular type of boiler for gas central heating and domestic hot water. They are easy to install, simple to use and economical to run. A combi boiler only heats water when a hot tap or shower is turned on, ensuring maximum efficiency. There is no need to find space for a water storage cylinder or have a tank in the loft. Hot water is delivered to your taps at mains pressure, so you can enjoy a powerful shower without the need for a pump.