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
BOILER DOES NOT RESPOND TO CH DEMAND
FAN NOT RUNNING ON DHW
FAN RUNNING ON DHW DEMAND BUT BURNER NOT LIGHTING
SPARKING OK BUT BURNER DOES NOT LIGHT AND ESTABLISH
CH OPERATION UNSATISFACTORY
DHW OPERATION UNSATISFACTORY