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
PUMP OK BUT FAN NOT RUNNING
FAN OK BUT NO SPARKING AT BURNER
SPARKING OK BUT BURNER DOES NOT LIGHT AND ESTABLISH
CH OPERATION UNSATISFACTORY
DHW OPERATION UNSATISFACTORY