Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
CH Demand
Gain access to fan assembly
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset the appliance as necessary.
Does the fan run with the demand?
Please select from one of the following outcomes:
FAN RUNS
FAN DOES NOT RUN
APPLIANCE WILL NOT RESET