Combi boilers and the SEDBUK Rating

Combi boilers, also known as combination boilers, are a common and well relied upon boiler in the UK. Many homes use this kind of boiler to keep up with hot water and heating demands. Buying them can be difficult, however, as there are so many companies and models to choose from. And what does half of the jargon used mean?

Combi boilers are, for example, often advertised as having a ‘SEDBUK’ rating. Many of these are A, although sometimes they are B or even lower. SEDBUK is commonly used in an advertisement without an explanation, leaving buyers who know nothing about boilers scratching their heads. So what is the SEDBUK rating?

SEDBUK is a rather long acronym, standing for ‘Seasonal Efficiency of Domestic Boilers in the UK’. It was developed by the government’s Energy Efficiency Best Practice Programme. It was done in conjunction with major boiler manufacturers so that the ratings and usage of the description was fair across the board.

In short, the SEDBUK rating gives an indication of the average annual efficiency that the domestic boiler can achieve in a household. This is all tested in a laboratory, taking into account the average usage of UK households, the temperatures specific to the UK, and the intricacies of the boiler technology involved. The bands that boilers fit into are based on percentages of these average annual efficiency marks. Band A are for boilers that have the highest percentages, and the bands go all the way down to G.

Combi boilers are therefore typically placed on the scale of these bands. The higher it is, the better the efficiency of the boiler. This is particularly useful when comparing two boilers. If one is rated higher than the other, you might consider that one to save you more energy and money in the future.