BoilerFaultCodesYour boiler is unable to switch between heating your house and providing hot water because an internal diverter component is stuck or broken.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: 3-Way Valve does not Operate and No DHW
What causes this fault?
This fault occurs when the mechanical part responsible for directing hot water to either your taps or your radiators becomes stuck or suffers an electrical failure. The most common reason is that the moving parts inside the valve have become seized by debris in the system water, or the small motor that pushes the valve has burnt out. Because the boiler cannot safely confirm where the heat is going, it stops operating to prevent overheating.
This issue is more frequent in autumn when the heating is turned on for the first time after summer, as the valve can seize up due to months of inactivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 9.1.35 — no call-out fees, no surprises.
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