Boilers Buderus is widely recognized as the world leader in hot water heating technology with boilers made from special low-temperature adapted, flexible and corrosion resistant GL-180M cast iron sections.  Profiled and beveled steel push nipples ensure long leak-free life.  Special sealing material provides a gas tight seal for operation.  The G115 modified three pass boiler is unsurpassed in efficiency without leaving any residue due to: Optimized combustion with positive pressure fired boilers and optimum chamber geometry without a heat consuming refractory or target wall. Minimal stack losses with modified three pass flue design with large heat transfer areas. Low standby losses with 3” thermal insulation around the entire block (even underneath). G115 boilers feature full swing, reversible swing burner doors for easy access, and quick and thorough cleaning and adjustable screw-in feet for easier leveling.  All tappings and flue connections are located in the rear for a clean, finished appearance.  There are baffles and clips for adjusting stack temperatures.  The G115 is suitable for sealed combustion and direct vent installations.