BoilerFaultCodesYour boiler has lost water pressure and has shut down to prevent damage, meaning you will not have any heating or hot water until the system is topped up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Lack of water fault (<0.5b)
What causes this fault?
This fault occurs when the water level inside your central heating system drops below the minimum safe limit. The most common reason is a slow leak from a radiator valve or pipework, but it can also happen if you have recently bled your radiators without topping the system back up.
This fault is frequently seen in autumn when homeowners turn their heating back on for the first time or bleed their radiators to remove air pockets.
DIY fix possible
Locate the filling loop, which is usually a flexible silver hose with two small taps underneath the boiler.Open both taps slowly until you hear water flowing and watch the pressure gauge rise.Close both taps firmly once the pressure gauge reaches between 1.0 and 1.5 bar.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 0.5bar — no call-out fees, no surprises.
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Glow-worm 18si 24ci is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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