Medium
D.35 on Vaillant Atmomax

Your boiler is struggling to bring the heating up to temperature, likely because there is air trapped in the system or the water pressure is too low.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Not relevant

DIY fix possible

Check the pressure gauge and top it up to 1.5 bar using the filling loopBleed all radiators in the house to release trapped airOnce bled and topped up, restart the boiler

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Related fault codes

F.22View →F.24View →D.34View →

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