Set Appliance State:

Mains Power Off
CH Demand
Gas On; Pilot On
Boiler On/Off Switch ON
CH Switch ON
DHW Switch in INSTANT position
CH Temperature Control in Maximum position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler, flow pipe and/or radiators start to heat up correctly?