BoilerFaultCodesYour boiler has shut down because a safety component has detected that the internal temperature reached a level high enough to potentially damage the system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Thermal fuse
What causes this fault?
This fault occurs when a safety sensor detects that the heat exchanger has reached an dangerously high temperature, often due to a lack of water flow or a buildup of debris. Because this component is designed to permanently break to protect the boiler from melting or catching fire, it means the system has suffered a significant overheat event. The most common reasons are a failed pump, a severe blockage in the pipework, or a lack of water in the system.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F29 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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