Set Appliance State:

CH Demand
Attach temperature clamp to boiler flow pipe as shown
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to run up to temperature while monitoring the flow temperature.
Does the boiler reach approximately 80°C and shut down without going to lockout?
Note:
To reduce time taken for this test you may wish to turn off some radiators.