F24 - Safety switch-off due to rapid temperature increase

What does F24 mean?

The Vaillant Ecotec Plus Boilers have shut down because they detected a very fast rise in temperature. This is a safety measure, often pointing to issues with water circulation or system pressure.

• The pump is blocked or has insufficient output.
• Air is trapped in the boiler or heating system.
• System pressure is too low.
• Non-return valve is blocked or incorrectly installed.

Click steps to track your progress.

1. 1

   Check that the pump is spinning correctly; if you are able, gently check with a screwdriver to feel it spinning strongly.

2. 2

   Verify NTC sensors are connected correctly and securely; check resistance and harness continuity if comfortable.

3. 3

   Try purging the system in case of an airlock by running the P00 deaeration program on your boiler.

4. 4

   Check the system pressure and top up if it's too low, following your boiler's instructions.

5. 5

   Drain the boiler and check the flow filter for any blockages.

6. 6

   Contact a professional to check the non-return valve or for other possible system blockages.