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.
Allow appliance to fire and system to heat.
Does the CH system heat satisfactorily?