F.76 — Overheating protection on primary heat exchanger responded

What does F.76 mean?

The overheating protection device on the primary heat exchanger has been activated, indicating an extreme overheating event. This is a critical safety shutdown.

• Cable or cable connections for the safety fuse in the primary heat exchanger are faulty.
• Primary heat exchanger itself is defective.

Click steps to track your progress.

1. 1

   Press the fault clearance key on the boiler to reset it.

2. 2

   Ensure all radiator valves are open and there is no restriction to water flow in the heating system.

3. 3

   If the fault persists, contact Vaillant Service Solutions immediately, as this is a serious safety concern.