I have an Ariston Eurocombi (A23). The problem is it doesn't realise the flame is lit. When I start it up and cause demand (run hot tap or turn on heating) it fires up the flame correctly, however, you can hear the igniter still clicking away. After about 7 seconds of this (flame working correctly, but igniter clicking) the boiler then shuts itself down and lights up the "Ignition failure" light. I can press the reset button but the same thing just happens again.
I don't think the problem is related to over-heating because if I leave it alone for a few hours, then try running hot water again, the problem is still there. However, If I turn it off, and off at the wall, then wait for at least an hour or so, I can get it to work again for about 1/2 an hour.
I assume the problem is either with whatever detects the flame is lit, or the board that responds to that sensor.
Any suggestions for how to diagnose (or better still, fix) the problem?