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Vaillant · Heat pumps · Vaillant aroTHERM plus with uniTOWER plus

S.275Building circuit: Flow rate too low

Name in the manufacturer's documentation (service manual): Building circuit: Flow rate too low[1]

In plain words (editorial)

The flow rate in the heating circuit is too low. The manual names a defective pump or all consumers (radiators, underfloor loops) being closed. It says to check the dirt filter, the stopcocks and thermostatic valves, and that the flow rate is at least 35% of the nominal flow rate.

When to call a service technician: Make sure not all radiator / underfloor valves are 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. 57 official manufacturer document quote verified S.275 Building circuit: Flow
  2. [2] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Check that the dirt filter is permeable
  3. [3] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Check the stopcocks and thermostatic valves
  4. [4] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Ensure that the flow rate is at least 35% of the nominal flow rate
  5. [5] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Check that the building circuit pump functions correctly
  6. [6] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Building circuit pump defective. All consumers in the heating
  7. [7] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 57 official manufacturer document quote verified Building circuit pump defective