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Vaillant · Heat pumps · Vaillant aroTHERM plus with uniTOWER plus

M.200Building circuit : Brine pressure low

Name in the manufacturer's documentation (service manual): Building circuit : Brine pressure low[1]

In plain words (editorial)

The pressure in the heating (building) circuit is low. The manual names pressure loss caused by leaks or air pockets, or a defective pressure sensor; its fix includes checking for leaks, topping up with heating water and purging.

When to call a service technician: If you are not sure how to top up, or the pressure keeps dropping, 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. 59 official manufacturer document quote verified M.200 Building circuit : Brine pressure low
  2. [2] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified Pressure loss in the building circuit due to leakages or air pockets
  3. [3] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified Building circuit pressure sensor is defective
  4. [4] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified Check the building circuit for leaks, top up with heating water and purge
  5. [5] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 59 official manufacturer document quote verified Check the plug contact on the PCB and on the wiring harness; check that the pressure sensor is working correctly and, if required, replace the pressure sensor