BoilerFaultCodesWhat the manual says
Manufacturer manualPressure drop in heating system too rapid
What causes this fault?
This fault occurs when the boiler detects a sudden and significant loss of water pressure within the central heating circuit. It is usually caused by a large leak in the pipework or a failure in internal components like the expansion vessel, which forces water out of the system. The boiler shuts down as a safety precaution to prevent the internal heat exchanger from overheating without enough water to cool it.
This fault is more common when the heating is first turned on after summer, as the change in temperature and pressure can stress weakened seals or joints, leading to new leaks.
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 2970 B: no call-out fees, no surprise bills.
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