BoilerFaultCodes 23 High
Your boiler has detected that the internal exhaust fan is not spinning fast enough to safely clear fumes, so it has shut down to prevent a safety risk.
Call an engineer soon
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fan speed too low
Typical repair cost £180-350 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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 23 — no call-out fees, no surprises.
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Chaffoteaux Calydra 100 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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