Set Appliance State:

CH Demand
Turn DHW control to 0 to deactivate preheat
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to reach approx 60°C
Remove CH demand
Burner will extinguish, Pump should continue to run for approx 15 secs (minimum) to clear heat.