BoilerFaultCodesYour boiler is providing hot water to your cylinder correctly, but the central heating for your radiators is not working.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: No CH But Cylinder Temperature Ok
What causes this fault?
This fault occurs when the boiler receives a signal to heat your hot water tank successfully, but the separate command to turn on your radiators is failing to reach the system. The most common reason is a faulty motorized zone valve that is stuck or a room thermostat that isn't communicating with the boiler. Because the boiler itself is working fine for hot water, the issue almost always lies with these external controls rather than the internal parts of the boiler.
This issue is frequently identified during the first cold spell of autumn when homeowners switch their heating back on after months of only using the boiler for hot water.
DIY fix possible
Check that your room thermostat or heating programmer is turned up and calling for heatEnsure any zone valves (usually found in the airing cupboard) are moving correctlyReset the boiler by turning the control knob to 'Reset' and then back to the original position
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 4.14 — no call-out fees, no surprises.
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