Unvented hot water systems have been commonplace for many years in Europe, South Africa, Australia and America but are a comparatively recent innovation in the UK, although ironically invented by an Englishman in 1861. Discerning householders are seeking increased performance from terminal fittings such as showers and continental style taps. Such fittings only function efficiently and effectively with hot and cold water at mains pressure, and this has encouraged the adoption of unvented systems in the UK.