Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Turn DHW thermostat to MAX
Use performance tester temperature probe to measure HW from taps
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow tap to run with an approx flow rate of 8 l/min.
Keep running tap for a minimum of 10 minutes to see if temperature from tap exceeds 65°C, runs hot then cool or cuts out on overheat.