Set Appliance State:

Mains Power Off
CH Demand
Selector switch to DHW and CH position
CH temperature selector to Max
DHW temperature selector to Min
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow burner to ignite and establish.
Turn selector switch to DHW position.
Does pump continue to run for approximately 30 seconds?