I am sensing a flame using a flame rod. I am using 12V AC at the input and at the output flame sensing circuit which is made of opamp, some resistors and capacitors, I get 1.6-2.4V when there is a flame, and 3.8-4V when there is a short circuit, and 5V when there is no flame. My flame sensing circuit seems to work fine but when there is a flame and short circuit happens at the same time my circuit only detects short and gives output of 3.8-4V. But I want my circuit to give output of 1.6-2.4V and see a flame instead of a short when both occur together. Is there any way I can achieve this? I would really appreciate your opinions on this.