Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Boiler CH thermostat set to MAX
Attach temperature clamp to the flow pipe after the thermistor as indicated by the red arrow
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the burner to ignite and the appliance to run with a central heating demand to maximum operating temperature.
The appliance should reach approximately 80°C and the burner should shut down.
When the temperature falls it should then re-ignite without going to lockout.
Does the appliance behave as described?