| 摘要 |
PURPOSE:To prevent unburnt gas from flowing to the outside of a device, by a method wherein an exhaust fan is driven by means of a delay circuit after a specified time elapsed after the starting of combustion. CONSTITUTION:Water flows through a heat exchanger 7, gas flows through a burner 2, and when combustion is started in a combustion part 1, the flame of each burner 2 is detected by means of a combustion detecting part 3. After such flame is detected, a combustion detecting signal is inputted to a delay circuit 4, a signal is delayed a specified time by means of the delay circuit 4, and the signal is inputted to a fan driving circuit 35. By means of such signal, an exhaust fan 6 is started to rotate to guide combustion exhaust gas to the outside of a device. This prevents unburnt gas from flowing to the outside of the device, resulting in prevention of production of uneasy feeling of a user. |
