Problem with Glow worm fuel saver 50?

Very odd. When was it last serviced? Odd because the boiler cannot differentiate between heating or hot water. As far as it is concerned it has only been instructed to light. Maybe the boiler doesn't go out when heating the water because it doesn't need to be on for as long so doesn't reach the point where it shuts down when in central heating mode.

Gas Safe Engineer in West Yorkshire
November 2013