In 2005 the Building Regulations introduced the new Part L demanding all new boilers installed to be categorized as high efficiency systems. This includes condensing boilers and combination (also known as combi) boilers which use a secondary heat exchanger (or an extra large single heat exchanger) to recoup the heat that would otherwise be expelled into the atmosphere via the boiler flue. The new Building Regulations Part L also called for heating controls, system insulation and hot water cylinders among other components to improve their respective energy efficiency levels.



