Manufactured by Buderus, World Leader in Hydronic Heating, the G615 series can be used with gas or oil – hot water only. It is manufactured with supply and return connections at the rear of the boiler, precision machined steel push nipple sectional construction, tongue and groove flue side sealing and a full swing door hinged for left or right. The G615 has a full 4” of thermal insulation for minimal standby heat losses and a 6” supply manifold with NPT control tappings. This product can be ordered factory assemble or knocked down for field assembly. Its precision casting eliminates the need for manual grinding. Due to the G615’s chamber geometry, there is no refractory or target cup needed. It is constructed of flexible GL-180M cast iron with a silicone “barrier skin” to resist corrosion and thermal shock.