Vokera compact 24 has heating but cuts out on hot water

[julesverne]

Gotta go look at a vokera comact 24 this morning its an old stlye on with the twin pass hex. Heating works fine but when hot water it cuts out straight away.
not come across this fault before. So was wondering if you guys had any ideas.

thanks in advance

 

[julesverne]

Sorted it dhw thermistor