We may have found other answers which could help you.
Click here for Boiler Heating GreenstarBosch W275 water heater fault?
Grundfos UPS 15 45 x18 central heating pump?
boiler wont stay alight?
Bosch 24i Combi-boiler?
How to heat water when therm. is off?
Bosch W275 water heater, diaphragm leaking?