Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach temperature clamp to flow pipe on right hand side of boiler
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to ignite and run on central heating operation.
Turn the CH temperature control to the maximum position - approximately 80°C.
The boiler should run to increase temperature to approximately 80°C then modulate to maintain flow temperature, shutting off completely if the temperature reaches approximately 85°C, without overheat occurring at any point.
Note.
1. To reduce the time taken for this test, reduce the heating circuit by turning off some radiators.
2. If the flow temperature is already at 80°C or greater the boiler should not fire until temperature reduces and then either maintain flow temperature or shut down as described above.