What does the Baxi Duo-tec F65 fault code mean?
The F65 fault code on a Baxi Duo-tec boiler indicates a problem with the domestic hot water (DHW) expansion vessel. This issue typically arises when the vessel is either waterlogged or has lost its charge, affecting the boiler’s ability to maintain proper pressure and function efficiently.
Common Causes
- Waterlogged Expansion Vessel: Over time, the expansion vessel can fill with water, preventing it from absorbing pressure fluctuations in the system.
- Loss of Air Charge: The air charge in the expansion vessel may diminish, leading to inadequate pressure management and triggering the fault code.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer for this issue, as working with the boiler’s pressure system can be dangerous and requires professional expertise. Attempting to fix it yourself may lead to further complications or safety hazards.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F65 fault code is around £150 to £250. This includes the cost of replacing the expansion vessel and any necessary labour, reflecting the complexity of the repair and the need for a qualified technician.