What does the Vaillant ecoTEC plus F44 fault code mean?
The F44 fault code on the Vaillant ecoTEC plus indicates a problem with the expansion vessel, which is responsible for maintaining system pressure and absorbing excess water expansion. A faulty expansion vessel can lead to pressure fluctuations and may cause the boiler to shut down to prevent damage.
Common Causes
- Loss of Pre-charge Pressure: The expansion vessel may have lost its pre-charge pressure, causing it to be ineffective in absorbing expansion.
- Physical Damage: The expansion vessel could be damaged or leaking, which would prevent it from functioning properly.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as working with the expansion vessel involves handling pressurised systems and could pose safety risks. Attempting to fix it yourself may lead to further complications.
Estimated Repair Cost (2026 UK Prices)
The estimated cost for replacing a faulty expansion vessel in a Vaillant ecoTEC plus boiler is around £250 to £350. This includes the cost of the part and labour, reflecting the complexity of the repair and the need for a qualified technician.