BoilerFaultCodesTechnical description
Return temperature higher than flow temperature
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water coming back from your heating system is hotter than the water it just sent out, which is physically impossible during normal operation. The most common reason is that one of the temperature sensors has failed or 'drifted' out of calibration, though it can also be triggered by a pump failure or a significant blockage that has completely stopped water from circulating.
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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