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. It is therefore appropriate that Grant has taken the lead with three Eco external modules, available in outputs between 15 and 35 kW. 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. Eco external boilers can be converted to sealed system operation by purchasing a pre-assembled kit from Grant (Product code: VTXECOSSKIT35). The kit comprises: an expansion vessel (size varies), automatic air vent, pressure relief valve, circulating pump, filling loop and pressure gauge. These can be fitted within the module casing, or conveniently sited within the building, located between the cold main and central heating return.