Viessmann 28

Medium

Vitocal — Secondary flow temp sensor — open circuit.

Viessmann 28: Secondary flow temp sensor — open circuit. This fault usually isn't an immediate stop, but should be checked soon.

Possible causes

Sensor (Pt 500) interrupted.

Check steps

Check resistance (Pt 500) at F8 / X5.8-X5.9.
Check/replace lead & sensor.

Affected parts

Vorlauf-Temperatursensor (Pt 500)

Safety note

Isolate power.

Source: Viessmann resmi servis kılavuzu — Serviceanleitung WO1C, section '28 Vorlaufsens. Sekundär' (p.90-91): 'Ursache: Unterbrechung Vorlauftemperatursensor Sekundärkreis.'

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

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