EKO DUO 500 hybrid boiler, 1700K BTUEKO DUO 500 hybrid boiler, 1700K BTU Commercial use automatic self cleaning hybrid boiler for very large hydronic heating systems, offering high hopper capacity, multi fuel flexibility, and configurable commercial setup options. Key Benefits Automatic self cleaning burner with rotary cast iron design for continuous commercial duty operation Flexible multi fuel capability for coal, pellets, grains, and biomass up to 1 1 2", plus manual feeding for wood