If your current boiler is over 12 years old it is likely to be around only 65% efficient. This means that for every £1 spent on fuel, only 65p is effectively being used to heat your home and 35p is wasted in hot air up the chimney.
Modern boilers are up to 96% efficient — an improvement of at least 15% on the above.
What are Condensing boilers?
Most types of boiler are also available as high efficiency or "condensing" boilers. There are high efficiency combination boilers, system boilers, or conventional boilers. The term `condensing' or high efficiency applies to the technology which is used to maximise boiler efficiency to use less fuel for more heat.
A condensing boiler is a high efficiency modern boiler that incorporates either a larger heat exchanger or even a second heat exchanger. It produces lower flue gas temperatures, lower flue gas emissions, and reduced fuel consumption . It typically converts more than 88% of the fuel used into useful heat, compared to, typically, 78% for modern conventional types.
By recovering and using heat that would otherwise be lost up the flue the best high efficiency boilers can operate with seasonal efficiencies in excess of 96%. Recovering the heat from the flue reduces the temperature of the flue gases to a point where water vapour produced during combustion is 'condensed out'. Thus the name high efficiency condensing boiler. A side effect is that this 'condensed out' water, known as condensate, which is acidic, has to be piped away to a drain or soakaway. All condensing boilers will produce ‘pluming’ from the flue terminal which appears as steam. This pluming can drift into neighbouring property causing annoyance and possible condensation on window glass or frames so careful consideration should be given to siting of the flue terminal especially if it may effect neighbouring property.
Although high efficiency boilers require a higher initial investment, they are very economical, and repay the extra initial cost in fuel savings.
A condensing boiler can work at over 96% efficiency.
New regulations have been in effect since April 2005, whereby new boilers have to be high-efficiency A and B-rated condensing boilers.
The Energy Efficiency Partnership for Homes have produced the following information:
Benefits & Myths about Condensing Boilers