Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Unlock and remove wireless controls key (pull downwards)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

CLICK HERE if you want information on the reason for this test.
Allow the appliance to run for CH, does the system now heat correctly?
Note:
Boiler will take approximately 45 seconds after power on before reacting to demand and the system temperature will need to be monitored to see if it is now satisfactory.