Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
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.
DHW temperature selector to maximum position.
Allow appliance burner to ignite and appliance to run.
Does the primary flow reach a temperature above 50 degrees C
(this may take between 50 and 60 seconds)?