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D.77 on Vaillant ecoTEC plus Regular

Your boiler is intentionally limiting the amount of power it uses to heat your hot water cylinder, which may result in your water taking longer to heat up than usual.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

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

Limitation of cylinder charging in output in kW

What causes this fault?

This occurs when your boiler's internal settings have been adjusted to cap the amount of energy provided to heat your hot water tank. It usually happens because your external cylinder controls or thermostat are requesting less heat than the boiler is capable of providing, or a specific limit has been set during installation to prevent the system from overheating. As a result, the boiler intentionally holds back its full power, leading to slower heat-up times for your taps and showers.

DIY fix possible

Check the hot water temperature settings on the boiler control panelEnsure the cylinder thermostat is not set unnecessarily highMonitor the time it takes for hot water to recover to see if it meets your needs

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Related fault codes

D.71View →D.22View →S.24View →

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