Observation:

Please choose from one of the following 5 options:
FAN DOES NOT RUN WITH A DEMAND FOR DHW OR CH

FAN RUNS BUT BURNER DOES NOT IGNITE ON BOTH DHW AND CH
BURNER IGNITES BUT DOES NOT ESTABLISH ON BOTH DHW AND CH
FAULT IS WITH THE HOT WATER ONLY - CENTRAL HEATING IS OK
FAULT IS WITH THE CENTRAL HEATING ONLY - DHW IS OK
BOILER FIRES ON CENTRAL HEATING WITH NO DEMAND PRESENT