Set Appliance State:

Mains Power Off
CH Demand
Boiler ON/OFF Switch OFF
CH Temperature Selector to Max
DHW Temperature Selector OFF
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Boiler ON/OFF Switch ON.
Allow Fan to run and Burner to ignite.
Does the CH System start to heat, and does the Boiler operate quietly? (Does not kettle).