BoilerFaultCodesYour boiler is currently pre-heating a small amount of water to ensure hot water arrives at your taps quickly when you turn them on.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: domestic hot water cycling mode active
What causes this fault?
This is not a fault, but rather a status message indicating that the boiler is warming up its internal heat exchanger. It happens periodically to ensure that you don't have to wait as long for hot water to reach your taps when you turn them on. Once the internal water reaches the required temperature, the code will disappear and the boiler will return to its normal standby state.
DIY fix possible
Check your user manual to see if you want to keep the 'Pre-heat' function on or offIf you wish to save energy, turn the hot water temperature dial slightly to deactivate the 'Eco' or 'Cycling' modeMonitor the boiler to ensure it transitions to 'S.24' or 'S.3' when a hot tap is actually opened
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A boiler cover plan would cover faults like S.20 — no call-out fees, no surprises.
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