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Viessmann · Heat pumps · Viessmann Vitocal 250-A (One Base, monobloc)

A.74Pressure drop in secondary circuit

Name in the manufacturer's documentation (service manual): Pressure drop in secondary circuit[1]

In plain words (editorial)

Pressure drop in the heating (secondary) circuit – you may hear unusual noise and notice unusual starting behaviour. The manual says to check the expansion vessel and to fill and vent the system.

When to call a service technician: If the pressure keeps dropping, contact your heating contractor.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 69 manufacturer document – copy from a distributor quote verified A.74
  2. [2] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 69 manufacturer document – copy from a distributor quote verified check the expansion vessel.
  3. [3] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 69 manufacturer document – copy from a distributor quote verified fill system and vent.
  4. [4] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 69 manufacturer document – copy from a distributor quote verified unusual operating noise