High
F.33 on Glow-worm Flexicom 24c / 28c

Your boiler is struggling to breathe properly because there is a blockage or a problem with the pipes that bring in fresh air and push out exhaust fumes.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Excessive pressure losses from the air/flue system

From this model's manual
Verified against the Glow Worm Flexicom 24c 28c installation & service manual, page 49.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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F.32View →F.61View →

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