F.11 High
Your boiler has detected that water isn't moving through the internal pipes correctly, causing it to shut down to prevent overheating.
Technical description: A blockage in the appliance is preventing the system from flowing as it should.
Typical repair cost: £180-£350 (including labour)
DIY fix possible
Check that all radiator valves are fully openEnsure the internal boiler valves underneath the unit are in the open positionCheck if the pump is making a humming sound, which may indicate it is stuck
Protect yourself from future repair bills
A boiler cover plan would cover faults like F.11 — no call-out fees, no surprises.
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Parts commonly replaced
- Central heating pump
- Main heat exchanger (flushing)
- Flow/Return thermistor
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