Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
CH temperature selector to MAX
Attach temperature clamp to the flow pipe near the APS
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the appliance to ignite and establish.
Monitor the appliance temperature.
Does the appliance reach a flow temperature of approximately 82°C then shut down, or does overheat occur?
Note:
To reduce time taken for this test you may wish to turn off some radiators.