Fast flash (blue) — Heat exchanger overheat

What does Fast flash mean?

The boiler's blue indicator light flashes quickly, indicating that the heat exchanger has overheated. This is a critical safety shutdown.

• Heat exchanger baffles are missing or incorrectly fitted
• Low water pressure or a dry system
• Air trapped in the system
• Issues with the pump or its connections
• Water leaks or blockages in the system
• Faulty safety thermostats

Click steps to track your progress.

1. 1

   Reset the boiler using the user control panel.

2. 2

   Check the system water pressure gauge and top up the system if it's below the recommended level (usually 1-1.5 bar).

3. 3

   Bleed radiators and pipes to ensure all air is removed from the heating system.

4. 4

   Check for any visible water leaks or obvious blockages in pipes around the boiler.

5. 5

   If the problem persists, contact a qualified service engineer to diagnose the circulation system.