bit of advice on fault finding

[pacplumber]

how to i go about testing the flow switch for hot water the boiler is only giving hot water when heating running hot but dont think it diverter valve as it has only been changed few months ago, not sure of it pcb heatingseems to be on all the time

any help would be much appreciated

 

[Agile]

Are you gas registered?

 

[Dan Robinson]

I'd certainly go about identifying the boiler first