High
Red Light on Glow-worm Swiftflow 100

Your boiler has stopped working because there is not enough water pressure in the central heating system.

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.

What the manual says

Manufacturer manual

‘LOW CENTRAL HEATING WATER PRESSURE’

From this model's manual
Verified against the Glow Worm Swift Flow 100 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the water level inside your heating system drops below the minimum level required for the boiler to operate safely. The most common reasons are a slow leak from a radiator valve or pipework, or a failure in internal components like the expansion vessel which helps manage system pressure.

This issue is frequently seen in autumn when the heating is turned on for the first time after summer, as the change in temperature can highlight existing small leaks or pressure drops.

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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