| 摘要 |
PURPOSE:To contrive an improvement in safety by making combustion suspend prior to generation of incomplete combustion, by making a discharge part pipe and a suction part pipe into thin pipes and using them both as an orifice and an access hole for pressure detection. CONSTITUTION:A suction part pipe 14 and a discharge part pipe 15 are provided respectively on a suction part 12 and a discharge part 13 of a fan 7 positioned at a downstream of a heat exchanger 3, the respective pipes 14, 15 are communicated by a pressure leading pipe 16 through a suction orifice 14-1 and a discharge orifice 15-1 with each other, and their synthetic pressure is led to a pressure sensor 11. Although the synthetic pressure (pressure of the pressure sensor 11) varies up to dimensions of respective orifices 14-1, 15-1, supposing that, as for an inside area, the suction orifice 14-1 is 1 and the discharge orifice is 2, they are made into a state of two-dotted chain line and pressure of about 7mm.H2O, 3mm.H2O and -2mm.H2O respectively. In addition to the above, as a back-flow quantity of exhaust gas to the suction part 12 from the discharge part 13 of the fan 7 is increased and exhaust capacity is decreased as a whole when an orifice diameter is made large, the diameter is made generally less than 10mm.. |
