Grant developed the first oil-fired external boiler in 1986 and although the concept was new to the oil market, it quite quickly became a popular addition to Grant's boiler range. Today, as around one in four oil boiler installations are external, Grant have expanded the number of options available with the launch of three competitively priced Eco External modules This high efficiency range has some unique features including a multi-directional factory fitted flue, external powder coated robust casing, built-in frost protection, mains isolating switch and a test switch. Sealed System Models Grant Vortex Eco External boilers are also available in sealed versions. These include a factory fitted expansion vessel, filling loop, pressure gauge, automatic air vent, pressure relief valve and high efficiency circulating pump, enabling boilers to be installed without the need for a feed and expansion tank in the loft.