Vaillant · Heat pumps · Vaillant aroTHERM plus with uniTOWER plus
S.516De-icing mode active
Name in the manufacturer's documentation (service manual): De-icing mode active
[1]
In plain words (editorial)
This is a status message, not a fault. The heat pump is defrosting (de-icing) the outdoor unit's heat exchanger; heating is interrupted meanwhile. The maximum de-icing time is 16 minutes.
When to call a service technician: No action needed.
✎ 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] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 58 official manufacturer document quote verified
S.516 De-icing mode active
- [2] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 58 official manufacturer document quote verified
The heat pump de-ices the outdoor unit's heat exchanger. The
- [3] Vaillant uniTOWER plus VIH QW 190/6 E – Operating, installation and maintenance instructions (0020291525_05) (0020291525_05) , p. 58 official manufacturer document quote verified
The heat pump de-ices the outdoor unit's heat exchanger