Observation:

USE THE FULL XSOL MODEL
or
Select from the list below if you are confident that the appliance has reached up to that point in the sequence correctly.
BOILER DOES NOT RESPOND TO DHW DEMAND
DHW DEMAND RECOGNISED BUT PUMP NOT RUNNING
PUMP OK BUT FAN NOT RUNNING ON DHW
FAN OK BUT NO SPARKING AT BURNER
BOILER DOES NOT LIGHT FOR A CH DEMAND
CH OPERATION UNSATISFACTORY
DHW OPERATION UNSATISFACTORY