Set Appliance State:

Mains Power Off
DHW temperature selector to 0 position
CH temperature selector to 0 position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Reset lockout as necessary.
Allow appliance to return to standby mode.
All heating controls calling.
CH temperature selector to maximum position.
Does the appliance ignite and run with heating demand?