Fault Codes / Viessmann / A4

Viessmann A4

High

Vitocal — Check valve — impermissible flow/temp rise.

Viessmann A4: Check valve — impermissible flow/temp rise. This fault noticeably affects operation.

Possible causes

Check valve not closing / gravity circulation.

Check steps

Check check valve(s) function & seating.
Check hydraulics & gravity brake.

Affected parts

Rückschlagklappe

Safety note

Hot water — scald risk.

Source: Viessmann resmi servis kılavuzu — Manual p.36: 'A4 Rückschlagklappe' = Informationsanzeige; Rückschlagklappe Solaranlage klemmt/defekt. Matches Enthalio DB in substance.

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

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