I have an ariston eurocomi boiler, when you try to get hot water or heating it starts pumping water but not firing up, after a few minutes a warning light comes on, which is the Low System Water LED. I have tried topping the system up using the small tap underneath but no better, the pressure goes up but still doesn't work.

Benjamin Blackford, December 2008

Try giving the side of the boiler a sharp tap when a tap is running. If the burner then lights it may well be the air pressure switch sticking.

DL, December 2008