Manufactured by Buderus, World Leader in Hydronic Heating, this series can be ordered factory assembled or knocked down for field assembly. It is constructed with a full 3.5” of thermal insulation for minimal standby heat losses, a full 3 pass flue design for maximum heat transfer and a deluxe, heavy gauge blue enameled jacket for a clean finished appearance. The G515 has a 4” supply manifold with N.P.T. control tappings and a precision push nipple sectional construction. It utilizes thermal shock proof boiler design at any return water temperature. The G515 has high combustion efficiencies – 88% on oil and 85.5% on gas.