BoilerFaultCodesTechnical 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.
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.
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