CWNS series horizontal internal-combustion hot water furnace is pan-shell type horizontal three-return fuel oil (gas) boiler developed by absorbing domestic, foreign advanced technology and experience. It runs automatically. After the burner atomizes fuel, the produced torch is full of the wave-type boiler inner and transfers radiation heat through inner wall. This is the first return. The high-temperature smoke gas produced during burning accumulates in burning room and turns to the second return (screw smoke pipe bundle area).