Isolate Mains Power to appliance as per TOPs P4
Ensure the following system checks are completed

Measurement:

System/boiler is correctly charged as necessary.
System/boiler is bled of air.
Gas inlet pressure is correct.
System by-pass is correctly adjusted as necessary.
Manual reset devices are set.
Note: The appliance is fitted with a single digit display which is located on the front of the control box behind the hinged door.
The display serves two functions:
1. To display current boiler operating status.
2. To help identify fault areas.
If the display shows a '4' flashing then it is possible that the appliance has been fired without water, checks should be made on the heat exchanger and its seals for damage and or water leaks.