BoilerFaultCodesGlow-worm Fan hunts Fault Code
Also written as FANHUNTS — same fault.
The Glow-worm Fan hunts fault code means: your boiler is struggling to maintain a steady fan speed, which is preventing it from completing its startup sequence and heating your home.. It appears on 2 Glow-worm models in our database.
Technical description: Replace printed circuit board.
What causes the Glow-worm Fan hunts fault?
This fault occurs when the boiler's control centre is no longer able to send a consistent voltage to the fan, causing it to speed up and slow down erratically. The most common reason is that the electrical components on the main circuit board have aged and degraded, losing their ability to regulate the startup sequence correctly.
This issue often becomes apparent during the first cold spell of autumn, when the circuit board is suddenly tasked with constant operation after being idle over the summer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Glow-worm models that show the Fan hunts fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Fan hunts fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026