BoilerFaultCodesGlow-worm 2.7bar Fault Code
Also written as 27BAR — same fault.
The Glow-worm 2.7bar fault code means: your boiler has too much water inside it, which has caused the pressure to rise to a level where the system may shut down or leak to protect itself.. It appears on 3 Glow-worm models in our database.
Technical description: Upper water pressure (>2.7b)
What causes the Glow-worm 2.7bar fault?
This fault occurs when the water pressure inside your heating system exceeds safe operating limits, often because the filling loop was left open or has started to leak water back into the system. It can also happen if the internal expansion vessel, which manages pressure changes as water heats up, has lost its air charge or failed. Effectively, there is too much water or not enough room for it to expand, forcing the boiler to shut down for safety.
This fault is frequently seen in autumn when homeowners top up their boiler pressure after a summer of inactivity and accidentally overfill the system.
DIY fix possible
Check that the filling loop valves are fully closedBleed water from a radiator using a bleed key to reduce pressureMonitor the pressure gauge until it returns to between 1.0 and 1.5 barOnce pressure is lowered, press the reset button
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Gas Safe Register →Glow-worm models that show the 2.7bar fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm 2.7bar 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