Furnace

The invention provides a furnace which comprises a furnace body with a furnace mouth and a hearth. A first combustion chamber, a second combustion chamber and a third combustion chamber are arranged inside the furnace body. The first combustion chamber and the second combustion chamber are arranged inside the furnace body side by side and inner cavities are communicated; the first combustion chamber is located under the furnace mouth, a fire bar is arranged below the first combustion chamber, an ash bucket is arranged under the fire bar, the third combustion chamber is located above the end, opposite to the furnace mouth, in the furnace body, a smoke outlet is formed in the upper end of the third combustion chamber, a heat exchange water tank assembly A is arranged inside the first combustion chamber, a heat exchange water tank assembly B is arranged inside the second combustion chamber, a heat exchange water tank assembly C is arranged inside the third combustion chamber, and the heatexchange water tank asse