How can I make my flame detector more reliable?
Another term you could search is &quot;flame proving sensor.&quot; This is the term we often use for the sensors in gas-fueled furnaces in the US.
Having only looked at the photos of your device, I'm guessing that its flame failure system may operate on the principle called &quot;flame rectification.&quot; In a nutshell, the flame allows a DC current of a few microamps to flow from the sensing rod, through the flame, to the burner. The technique depends on clean surfaces on the sensing rod and the burner; combustion of contaminated air can cause an invisible electrically insulating coating to form on either surface. It is easily corrected by cleaning the surfaces with a gentle abrasive.
My best guess is that ignition is achieved by causing a spark to jump from the little metal post to the burner ring. After the ignition spark is finished maybe the post then serves as the sensing electrode.
I'd suggest ensuring the metal surfaces of the burner ring and whatever it sits on are clean and that they seat together well. Also clean the spark igniter post. If it's easy to do, remove some covers and confirm wires and other parts are connected snugly.