BoilerFaultCodesWhat the manual says
Manufacturer manualDry fire protection (temperature gradient of flow NTC too steep) | .Air in boiler/system, pump blocked or defective, pump output too low
What causes this fault?
This fault occurs when the boiler detects a sudden, sharp rise in temperature because the heated water isn't moving away from the burner quickly enough. The most common reasons are a lack of water pressure in the system, a pump that has seized up, or a physical blockage like sludge or debris preventing circulation.
This issue is more frequent in autumn when heating systems are turned back on after being idle all summer, which can cause the internal pump to stick.
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.24: no call-out fees, no surprise bills.
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