I've just moved house & inherited a boiler with attitude! When my ch or water is turned on, the flame lights & then dies back. It ususally works on the 2nd attempt but, means I can't set my ch on timed & I have to give guests a crash course in how to turn on the water (which incidentally works 1st time if the heating is on!) I've had the PCB, Thermistor & every connecting lead to the PCB replaced at great expense bur to no effect, the problem is still there. Can anyone suggest what it may be? I can't believe that this is a unique fault. Thanks in advance.