Need to Replace a Part?
If your Ferroli boiler shows an F40 error, this usually means the water pressure is too high. To fix this issue effectively, you may need to replace a faulty component. At Suner, we have a full catalog of original Ferroli parts available for fast delivery.
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What Does the F40 Error Mean?
The F40 error indicates overpressure in the primary heating circuit. It’s a generic warning that may appear due to excess water, faulty safety components, or a failing expansion vessel.
This guide explains how to fix the error quickly based on the root cause.
Table of Causes and Solutions
| Possible Cause | Explanation | Recommended Solution |
| Filling valve accidentally left open | Water keeps entering the circuit | Close the filling valve and release pressure by draining water from a radiator or drain valve |
| Filling valve stuck open or leaking | Continuous water input due to valve failure | Replace the filling valve |
| Faulty safety valve | The valve doesn’t release excess pressure as it should | Replace the safety valve with a new one (typically rated for 3 bar) |
| Expansion vessel is deflated | The internal air charge is lost, can’t absorb pressure changes | Recharge the air section or replace the expansion vessel |
| Expansion vessel membrane is damaged | The vessel is split inside and filled with water | Replace the expansion vessel completely |
When Should You Take Action?
This error can appear sporadically or become constant, depending on how severe the overpressure is. If:
- The F40 error shows occasionally, and resetting the boiler solves it: check the pressure gauge and perform a manual drainage if necessary.
- The F40 error is constant, or pressure rises again after draining: one or more components are likely faulty and must be replaced.
Conclusion
The F40 error on Ferroli boilers is a clear sign that your system is operating under excessive pressure. In most cases, the problem is due to:
- A filling valve that was left open or is stuck
- A faulty safety valve that doesn’t release pressure
- A damaged expansion vessel that can’t balance the system
Fixing it is usually simple if you act quickly. And remember, for any component replacement, use original Ferroli parts from Suner to guarantee compatibility and performance.