High Lockout
F.22 on Glow-worm Energy Heat

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Safety switch-off – low water pressure in boiler

What causes this fault?

This fault occurs when the water pressure inside your heating system drops below the minimum level required for the boiler to fire up safely. The most common reason is a slow leak from a radiator valve or pipework, though it can also happen if you have recently bled your radiators and haven't topped the pressure back up.

This fault often appears in autumn when homeowners turn their heating back on for the first time, as small leaks may have developed or radiators may have been bled during the summer break.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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