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Poor-quality water

Poor-quality heating water detected

Vaillant · ecoTEC plus Boilers

What does Poor-quality water mean?

The heating water in your system may appear discoloured, contain sediment, or metallic particles, or have an unbalanced pH value. These issues can lead to material damage within the heating system.

Common Causes

  • Sediment buildup in the system
  • Presence of magnetite (iron oxide) from corrosion
  • Incorrect pH balance of the water (below 8.2 or above 10.0)
  • Oxygen entering the heating circuit

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Carefully remove a small amount of water from the heating circuit for visual inspection.

  2. 2

    If the water contains sedimentary materials, the system needs professional desludging.

  3. 3

    Check the water for magnetite using a magnetic rod; if present, the system requires professional cleaning and corrosion protection.

  4. 4

    Measure the pH value of the water; if it's outside the range of 8.2 to 10.0, the system water needs professional treatment.

  5. 5

    Ensure that no new oxygen can get into the heating water by checking system integrity and pressure.

Browse all codes in this manual (146)
Verified technical data. Last updated: April 2026

Related Faults

Communication fault (display/PCB)Communication fault - No communication with the PCBD.092 = 1D.092 = 1 — actoSTOR module connection errorF.0F.0 — Flow–NTC open circuit
Source: Vaillant ecoTEC plus Boilers
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