Set Appliance State:

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

Observation:

Press reset to cancel purge cycle countdown.
Allow boiler to fire and run for central heating.
Does the temperature reach Max (approximately 85°C) without overheating?
Note:
The time this takes can be reduced by turning off some radiators.