D6 — Internal heat bank overflow

What does D6 mean?

The boiler has detected an internal heat bank overflow. This indicates a problem with the internal hot water storage or expansion system.

• Overheating of the internal heat bank.
• Faulty expansion vessel or relief valve.
• sensor error related to the heat bank.

Click steps to track your progress.

1. 1

   Turn off the boiler at the mains and allow it to cool down completely.

2. 2

   Check the system pressure and ensure it is not excessively high.

3. 3

   Reset the boiler. If the overflow recurs, contact a qualified heating engineer for immediate inspection.