BoilerFaultCodesTechnical description
Flow rate in heat exchanger is too low
What causes this fault?
This fault occurs when water is unable to circulate through the boiler's main heat exchanger at the required speed to safely carry heat away. The most common reasons are a failing internal pump, a build-up of sludge or debris blocking the pipework, or a secondary heat exchanger that has become restricted over time.
This issue often comes to light during the first cold spell of autumn when the heating is turned back on and the pump or system is pushed to work harder after sitting idle all 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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