| 摘要 |
PURPOSE:To provide a safety device adapted to stop combustion and resume operation readily in the event of abnormal thermister operation and abnormal combustion under a lack or shortness of water, etc. CONSTITUTION:The signal of thermister 3 is converted into a digital signal by means of an A/D converter 18, constantly inputting to a CPU5 which is adapted to judge and output in response to the digital signal. In the event of thermister 3 being open or short circuited, the resistance of thermister 3 reaches infinity OMEGA or 0OMEGA respectively, and an A/D converted value 8b<1> t is converted into &H ''00'' or &H ''FF'' which are the value definitely showing the unusual state of the device, and the abnormality of the thermister is determined. When a combustion under a lack or shortness of water or other abnormal combustion takes place, a water delivery tube 7 and a heat exchanger 8 is heated up to an unusual level, and the CPU5 is enabled to detect the abnormal combustion state, and a temperature fuse is melted. Thus, the combustion can be stopped before the actuation of high limit switch 2. In consequence, the resumption of the operation is made avaliable by the manipulation of power reset etc., resulting in an improved using convenience. |
