Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Unscrew control panel and hook on lower hooks so condensate trap is visible
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to run and syphon to fill fully. Wait for the syphon to discharge.
Does the syphon side of the trap discharge completely within approx 5-7 seconds?
Or does the condensate trickle from the trap or appear not to drain at all?