i have a jaquar cobination boiler, its starts up o/k then it will shut down, f1 is displayed on the led display, i think it maybe the flame sensing elctrode because i removed this and heated it up on a gas ring and there was no alteration in resistance.

g steadman, October 2008

You won't get alteration in resistance
flame sensing electrode works on flame rectification through the spark (to hard to explain)
What does F1 display mean
dun know should say in makers instruction

yas, October 2008