| 摘要 |
PURPOSE:To prevent the temperature of exhaust gas from dropping excessively while increasing the heat-exchangeable capacity of a heat exchanger for heating water and enable water and air to be heated satisfactorily by bonding a heat insulating material to the inner wall of combustion gas header. CONSTITUTION:A heat insulating material 20 is bonded to the inner wall of a combustion gas header 7 to raise combustion gas temperature T1 and the stream of a combustion gas is restrained between plate fins 25 to increase heat transmission coefficient K. Therefore, the radiation of heat from the combustion gas header 7 is reduced and the temperature of the combustion gas flowing from the combustion gas header into a heat exchanger 8 for heating water is raised by and equivalent portion of the reduced heat. Since the heat- exchangeable amount of the heat exchanger for heating water is proportional to the difference in temperature between the combustion gas and water, a drop in the temperature of exhaust gas can be prevented by the part of a rise in the combustion gas temperature while increasing the heat-exchangeable amount. |
