Bunnyman, have now taken the motherboard out inspected it and can find nothing that is immediately wrong so I guess I must now look to find a replacement, thanks for your input I will post with any further developments.
Agile,Yes the DHW diverter valve microswitch is open circuit when the DHW is off, the cam is in the correct position and when the microswitch is activated manually the DHW fires up.
Bunnyman, The thermostat shaft is plastic in answer to your question, why do you ask?
Bunnyman, I have already tried what you are asking and suspected it could be one of the boards, the only problem is which board. Everything works as it should when the DHW is running so the fan and pump control would appear ok, its either the main board or the thermostat board (so I am told)...
First time posting on here but here it goes.
I have an ageing Vaillant VCW242 boiler that up until now has been working fine.
I have not had any work done on this boiler in the last 3 years since the heat exchanger was replaced apart from regular services.
The problem I am having is...