The F75 fault code on the Vaillant Ecotec boiler range refers to a pressure issue when the pump starts. The pump provides the circulation of water around the boiler and to the radiators and hot water cylinders if installed. The sensor triggers when the pressure drops. There are several reasons why the F75 fault code comes on, some of which you can check yourself.
The reasons for a F75 fault code are:
- Low water pressure
- Air lock
- Pump sticking or seizing up
- Blockage in boiler/system
- Fault with expansion vessel
- Faulty sensor
F75 faults you can check yourself
Low water pressure is most common reason for this fault. Check the gauge to see if the needle is pointing towards the correct area. If required, add more pressure to the boiler (it may only require a small amount to fix the issue). Reset the boiler and observe the operational steps. The pump should make a low rumble noise. If it isn’t, there could be air in the system. This happens when you haven’t used the boiler for a while. For instance, if you have drained the heating for system upgrades or long periods of down time. Check and bleed the system thoroughly and adjust the boiler pressure. The boiler should now clear the air automatically.
Faults that need a Gas Safe Qualified Engineer
The remaining faults on the list will require the expertise of a qualified professional. They will diagnose the issue and provide you with any other recommendations to ensure the boiler works smoothly. It may require parts for some issues and we highly recommend a check on the condition of the central heating water because this can lead to further problems if the water condition is poor.