High
F.24 on Vaillant ecoTEC plus Aquaplus

Your boiler has detected that it is heating up too quickly, which usually means there is air trapped inside the system or water is not circulating properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Dry fire protection (temperature gradient of flow NTC too steep) | Air in boiler/system, pump blocked or defective, pump output too low

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
Search the official register →

Related fault codes

F.22View →F.23View →

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Radiators cold at the bottom

Sludge build-up — needs flushing, not bleeding.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →