Vaillant VCW GB 242 EH, heating problem

[danellajoe1]

I have a problem on the heating side of a Vaillant VCW GB 242 EH. When the heating is put on it runs for about 5 mins then shuts down, it then tries to fire up again, this sometimes works but only for about 30 seconds then it goes to lockout, the reset button pops out and red light comes on. I have looked for any obvious visual faults and checked the workings of certain components but now would like a few pointers. DHW works ok.
Thanks

 

[Agile]

Sounds like a lack of flow in the cH circuit

Tony

 

[danellajoe1]

Thanks Tony, so a new pump may be the answer?

Mark

 

[kevplumb]

get the ntc connection checked