BoilerFaultCodesWhat the manual says
Manufacturer manualDry fire protection | No water in appliance, pump cable defective, pump blocked or defective, pump output too low
What causes this fault?
This fault occurs when the boiler detects a critical lack of water or a failure in the circulation system, preventing it from moving heat away from the burner. The most common reason is a significant drop in system pressure, but it can also be triggered if the pump has seized or failed to start. Without sufficient water flow, the internal sensors shut the system down immediately to prevent the heat exchanger from melting or cracking.
This fault is frequently seen in autumn when heating systems are turned back on after being idle all summer, which can cause the internal pump to seize.
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.
Avoid the next call-out bill
A cover plan would handle faults like F.22: no call-out fees, no surprise bills.
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