All plumbing trainees very quickly learn that installing a condensing boiler provides the most efficient energy saving option when considering the best form of 'green energy' domestic heating.Condensing boilers have been widely used on the continent and in North America since the early eighties, but in the UK, condensing boilers still represent a small percentage of total boiler sales. Lack of awareness and the fear of new technology have been two key factors responsible for the delay, resulting in the British consumer paying more for winter gas supply than their European and North American counterparts.Condensing boilers have also been seen as expensive, even though payback periods and lower running costs were favourable, yet the price difference has been just too great. However, with the recent announcement of the boiler scrappage scheme, which will pay to replace old boilers with new ones, the benefits of installing an A rated condensing boiler will be now within reach of some 125, 000 homes urgently requiring replacement of their inefficient G rated boiler.It means a big challenge ahead for both experienced plumbers and those currently training to be a plumber in order to fully acquaint themselves with the necessary knowledge and practical training. Courses like the City & Guilds NVQ 6129 level 2 are a foundation course to prepare for NVQ 6129 level 3 and both involve green energy issues which can be followed on 'renewable' green energy courses. Condensing boilers are suitable for replacing most existing boilers, either floor standing or wall-hung with extended flue options, if required.Finding a location and installing a condensing boiler only differs from a conventional boiler in the requirement for a condensate drain, and consideration of pluming.They are available as regular or combination boilers and are installed similarly to non- condensing boilers and is not necessary to install oversized radiators to give a worthwhile gain as the main efficiency benefit from a condensing boiler comes from having a larger heat exchanger, typically 13 percentage points greater than for non-condensing boilers.