All boilers serve a common purpose, but their efficiency can vary massively. Boilers are categorized by an Energy Efficiency Rating, which indicates how much energy they use and how much is wasted. Modern condensing boilers are labelled between 92 to 94% efficiency – this means they are given an efficiency rating of A. Boiler efficiency is ranked from to A to G, with G-Rated boilers converting just 70% of Gas into useful heating.
