Set Appliance State:

Mains Power Off
CH Demand
Boiler Thermal Store must be at MAXIMUM TEMPERATURE, to ensure this, run the boiler until the Green Neon extinguishes then;
Models with Programmer: Rocker Switch to Timed, Programmer C/H demand to ON.
Models without Programmer: Central Heating Switch to ON.
Note:
If the Appliance is only utilised for Hot Water (no CH System) select the "Boiler flow pipe/radiators heating rapidly" option below.
Gas On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Does the Boiler Flow Pipe and/or the Radiators get hot?