BoilerFaultCodesYour boiler is getting too hot too quickly, usually because the water is not flowing through the system as fast as it should.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Temperature differential exceeded
What causes this fault?
This fault occurs when the internal sensors detect that the temperature of the water is rising much faster than the boiler can safely handle. It is usually caused by a blockage in the pipework, a build-up of sludge, or a pump that has failed and is no longer pushing water around your radiators. Essentially, the heat being generated has nowhere to go, so the boiler shuts down to prevent internal damage.
This issue often surfaces in autumn when the heating is turned back on for the first time, as internal pump parts can seize up after sitting idle over the summer.
DIY fix possible
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Ensure all radiator valves are fully open to allow water to circulate.Restart the boiler using the reset button/dial to see if the fault clears.
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A boiler cover plan would cover faults like E30 — no call-out fees, no surprises.
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Vokera Hydra is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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