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Vaillant · Heat pumps · Vaillant aroTHERM plus with uniTOWER plus

F.731High-pressure switch open

Name in the manufacturer's documentation (service manual): High-pressure switch open[1]

In plain words (editorial)

The high-pressure switch in the outdoor unit tripped – the refrigerant pressure is too high. The manual names too little heat taken away by the condenser, too low water flow (e.g. single-room controls closing in an underfloor heating system), a blocked dirt filter, or too low refrigerant flow.

When to call a service technician: Make sure the room/underfloor valves are not all closed. If it repeats, contact a heating engineer.

✎ 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] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified High-pressure switch open
  2. [2] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Refrigerant pressure too high. The
  3. [3] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Insufficient energy output via the
  4. [4] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Too low a volume flow as a result
  5. [5] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Inform customer service.
  6. [6] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Purging the building circuit
  7. [7] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Check that the dirt filter that is in
  8. [8] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Inform customer service.
  9. [9] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Cooling mode: Check the fan unit for
  10. [10] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Check the high-pressure switch and
  11. [11] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 60 official manufacturer document quote verified Reset the high-pressure switch and