EKO DUO 15 hybrid boiler, 65K BTUEKO DUO 15 hybrid boiler, 65K BTU Automatic self cleaning hybrid boiler for smaller hydronic systems, combining multi fuel flexibility, smart control, and long unattended operation in a compact EKO DUO platform. Key Benefits Automatic self cleaning burner with rotary cast iron design for reliable solid fuel combustion Flexible multi fuel capability for coal, pellets, grains, and biomass up to 1 1 2", plus manual feeding for wood chips and peat