Boiler efficiency and SEDBUK

Boiler efficiency

In keeping with the Bosch tradition for excellence and energy efficiency, every Worcester Greenstar boiler is rated in the highest possible efficiency category – SEDBUK Band ‘A’. That’s at least 90% efficient, which means less natural gas, LPG or oil is wasted.

SEDBUK rating and condensing

SEDBUK is an acronym, standing for ‘Seasonal Efficiency of a Domestic Boiler in the UK’. The system was developed under the UK Government’s energy efficiency best practice programme with the co-operation of boiler manufacturers and provides a basis for fair comparison of different models of boilers.

The SEDBUK rating is the average annual efficiency achieved in typical domestic situations, making sensible assumptions about climate, control, pattern of usage and other similar factors. The rating is calculated from laboratory tests together with other important factors such as boiler type, fuel used, ignition type, UK climate, boiler water content and typical domestic usage patterns. For estimating annual fuel running costs SEDBUK is a better guide than laboratory test results alone.

The boiler’s performance is scored, enabling the boiler to be placed in a banding system using a scale from ‘A’ to ‘G’. ‘A’ rated boilers are the most efficient and usually termed ‘condensing’ boilers.

Condensing

The term ‘condensing’ is derived from the creation of condensation within a boiler’s heat exchanger or flue. When combustion of any kind takes place water vapour is always produced - this liquid usually needs to be conveyed away from the boiler to a drain via a plastic discharge pipe run by the installer.

In a standard efficiency boiler the flue gas temperature is kept relatively high to avoid condensation and its related issues. But in a high efficiency boiler, much of the heat produced in the combustion process is absorbed by the heat exchanger into the heating water and very little is wasted to the atmosphere via the flue, hence less fuel is burned to achieve the same results but the consequence is condensation which is dealt with in the appropriate manner.