Low
F21 on Ferroli Bluehelix HiTech RRT

Your boiler has detected that there is a bit too much water pressure in the system, which may cause it to stop working for safety.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

System pressure slightly high — pressure too high or wrong parameter b04

From this model's manual
Verified against the Ferroli Bluehelix Hitech Rrt installation & service manual, page 47.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate a radiator bleed valve and use a radiator key to release a small amount of water into a cloth or bowl.Monitor the pressure gauge on the boiler front or display until it drops to between 1.0 and 1.5 bar.Restart the boiler to see if the fault code clears.

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