Set Appliance State:

CH Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler respond to a CH demand
(CH symbol flashing and temperature displayed)?
Notes.
1. It may take approximately 60 seconds for the boiler to recognise a CH demand after a DHW demand, this will depend upon the boiler status. (Status code guidance CLICK HERE)
2. On some appliances the pressure may also be displayed until CH demand is recognised.