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S.31

S.31 — No Heat Demand in Summer Operating Mode (EcoTEC 65kW)

Vaillant · Turbomax Plus Boilers

What does S.31 mean?

This status indicates that the EcoTEC 65kW boiler is currently set to 'Summer Mode' and therefore will not provide central heating. It will only operate for hot water demands.

Common Causes

  • Boiler set to Summer Operating Mode
  • No demand for central heating

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    If central heating is desired, check your boiler's operating mode and switch it to 'Winter' or 'Heating' mode.

  2. 2

    Ensure your room thermostat is set to a temperature higher than the current room temperature.

  3. 3

    Check your programmer/timer settings for heating schedules.

  4. 4

    If you've switched modes and heating still isn't working, restart the boiler.

Browse all codes in this manual (55)
Verified technical data. Last updated: April 2026

Related Faults

F.00F.00 — Flow NTC Cable Defective or Broken (Turbomax Plus)F.00, F.04, F.05, F.10, F.14, F.15F.00, F.04, F.05, F.10, F.14, F.15 — NTC Sensor Fault (Ecomax Pro 828E)F.01F.01 — Feed Temperature Sensor (NTC) Fault or Open Circuit (Turbomax Plus)
Source: Vaillant Turbomax Plus Boilers
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