PURPOSE: To utilize waste sawdust as a heat source for a boiler generating steam and hot water by drying waste sawdust accumulated in a fuel tank, supplying a predetermined quantity of waste sawdust at a time to a combustion chamber, and heating the pipeline of a boiler chamber provided at the upper part of the combustion chamber.

CONSTITUTION: Air is introduced into a combustion chamber 8 by a blower 9. The state at the upper part of a grate R of a combustion chamber 8 is that waste sawdust is formed in a conical shape. Control of air sent from the blower 9 is carried out by confirming the force of fire through a peep-hole provided on the wall surface of the combustion chamber 8. Waste dry heat from the combustion chamber 8 is passed through a tubular body part having pipes 7 in a boiler chamber 6 to generate steam and hot water. Then, the waste sawdust is passed through a drying chamber 2, and a second flue part 5' continuous to the drying chamber 2 is finally connected to the cyclone 11 of a dust collector. This dust collector has a trapping ratio of 60W75%. Granules having coarse grains trapped therein are taken out and recharged into the drying chamber 2 and mixed in the waste sawdust to be burnt. Furthermore, fine granules are recovered by a shower system. Thereby, the waste sawdust is burnt and it is possible to generate steam and hot water by the heat of the sawdust.