Glow-worm · Ultimate 3 Regular
F.10 boiler fault code
Ultimate 3 25r -A (H-GB)
What F.10 means
Short circuit: Flow temperature sensor
Safe check: Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
Gas Safe registered engineer: The code remains or returns after the step above, or no home step applies; arrange diagnosis by a Gas Safe registered engineer.
Find a Gas Safe engineerA boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, or someone has possible carbon-monoxide symptoms, leave and call 0800 111 999 from outside.
Official source: Glow-worm Ultimate 3 Regular (25r -A H-GB) Installation and maintenance instructions · Appendix E “Overview of fault codes”, F.10, printed p.38