| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To simplify a control circuit and to improve the reliability of a heat exchanger blockage state monitoring circuit by monitoring the variation of voltage of a primary side, at a secondary side with respect to the control circuit of a gas water heater. <P>SOLUTION: The blockage state of a heat exchanger is diagnosed by comparing a rotating frequency signal 7 from a microcomputer 4 with a rotating frequency feedback signal 8 from a combustion fan, and a degree of influence by the variation of voltage detected by a power source voltage variation detecting means and the variation of voltage determined on the basis of the relationship between a rotating frequency signal to the variation of power source voltage stored in advance and a rotating frequency feedback signal, is reflected on a result of the comparison, whereby the control circuit is simplified, and the reliability on the heat exchanger blockage state monitoring circuit is improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
