Viessmann 39

High

Vitocal — Open circuit, primary circuit return temperature sensor (heat pump air or brine outlet) — emergency operation using flow value −2K.

Viessmann 39: Open circuit, primary circuit return temperature sensor (heat pump air or brine outlet) — emergency operation using flow value −2K. This fault noticeably affects operation.

Possible causes

Primary circuit return temperature sensor open circuit.

Check steps

Check resistance (Pt500A) at terminals X25.3/X25.4, replace sensor if needed.

Affected parts

Rücklauftemperaturfühler Primär

Safety note

Isolate power before testing.

Source: Viessmann Vitotronic 200 Typ WO1C Serviceanleitung für die Fachkraft (2017-01), "Übersicht der Meldungen" §Störungsbehebung, Art.-Nr. 5813961

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

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