In message , "Mungo \"two sheds\"
Toadfoot" writes
I've got a New World Royale 600 gas cooker with a self-lighting oven - you
turn the gas on and the sparker clicks away until the oven lights.

First, how's it do that then?

Mirrors and magic Si

As they say, keep up at t'back

Just the same as ignition circuits in central heating boilers (which
must get discussed at least once a month), a flame acts like a resistive
diode, which is what the flame sense circuit senses


Second, it only works when it feels like it - about 7 times in 10. Any idea
why?

Electrode not properly in the flame, intermittent contact on the HT
lead, bad earthing, gremlins just out to get you.

--
geoff