Observation:

Only jump into the sequence if you are confident that the appliance has reached up to that point in the sequence correctly
Please select from one of the options below:
BOILER DOES NOT RECOGNISE A DHW DEMAND
DHW DEMAND RECOGNISED BUT PUMP NOT RUNNING
DHW DEMAND RECOGNISED BUT FAN NOT RUNNING
FAN RUNS BUT BURNER DOES NOT IGNITE
FAN RUNS BURNER IGNITES BUT DOES NOT ESTABLISH
DHW OPERATION UNSATISFACTORY
BOILER DOES NOT RECOGNISE A CH DEMAND
CH OPERATION UNSATISFACTORY BUT DHW OPERATION OK
DHW AND CH OK BUT PREHEAT OPERATION UNSATISFACTORY