Potterton Combi tripping out

[rolyatescort]

My Potterton Puma Combi has recently started tripping out. If you don't use any hot water for a few hours the boiler trips out and the red light comes on and the tap just runs cold, as soon as you reset you can get hot water from the tap. It is fine once in use, i.e. will fill a bath with hot water without tripping out. It has also started making some fairly loud clanking and gurgling sounds. The heating side of it has not been used for a couple of months so i have no idea if that is ok or not.

Have you any ideas what could be wrong with it? You've always managed to steer me right in the past, don't fail me now, please?

Thanks, Tony.

 

[ChrisR]

Standard problem, the Domestic (hot) Water Flow Switch has stuck on. You'll find more if you search here. You can dismantle and clean it or buy a new one. <£50.