Malfunctioning CH system

[trickyrad]

I have a 7 year old Potterton 80E pumped system with a Grundfos 15/50 pump. The system has stopped working. When it is switched on, the boiler comes on and switches off after about 1 minute. ( I've had to switch it on using the reset button under boiler ). Previous to this the pump was making a coffee grinder noise on startup and which eventually disappeared. When I put my ear to the pump I can hear it whirring. Any ideas? If the pump is kaput how can I confirm that it is the pump? I know the information is probably very basic but I can supply more.

 

[ChrisR]

Fair bet your pump is knackd. Once they've made grinding noises they often run slow. You could also take the head off it to feel for play, check the impeller isn't blocked.
If you have a suitable meter check the capacitor.