BoilerFaultCodesYour boiler is temporarily heating the internal tank to ensure hot water is ready for use, which is a normal operating status rather than a fault.
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 status occurs when the boiler detects that the temperature in the integrated hot water storage tank has dropped below the required level. The boiler temporarily stops circulating heat to your radiators to focus all its energy on reheating the internal cylinder. Once the water inside the tank reaches the correct temperature, the boiler will automatically return to its normal heating schedule.
DIY fix possible
Check your hot water cylinder thermostat settingsEnsure your heating and hot water timers are set correctlyMonitor the boiler to see if it moves to a standard heating or standby mode once the water is warm
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A boiler cover plan would cover faults like S.20 — no call-out fees, no surprises.
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