BoilerFaultCodesYour heat pump has stopped working because water is not circulating correctly through the outdoor unit.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No Water Flow, through Outdoor Unit, 10 times in succession
What causes this fault?
This fault occurs when the system detects that water is not moving through the outdoor unit quickly enough to safely transfer heat. The most common reasons include a blockage in the pipework, a faulty internal pump, or a build-up of debris in the system filter that is choking the flow.
This issue is more frequent during the first cold snaps of winter when the system is under higher load and any existing debris or pump sluggishness becomes critical.
DIY fix possible
Check that your central heating system pressure is between 1.0 and 1.5 barEnsure all radiator valves and external isolation valves are fully openCheck the outdoor unit for any debris or ice blocking the areaReset the system at the control panel
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 9.1.2 — 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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