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Vaillant aroTHERM fault M32

Low heating installation filling pressure warning

Heat pump

What it means

Message M32 appears when the filling pressure of the heating installation falls below 0.07 MPa (0.7 bar). This is a warning indication, not a lockout fault, and is accompanied by a symbol displayed after approximately one minute.

Likely causes

  1. Loss of heating water pressure
  2. Leak in heating installation
  3. Loss of heating water from the installation
  4. Leak in the heating circuit
  5. Insufficient initial filling pressure
  6. Pressure drop in heating installation
  7. Low filling pressure in heating installation
  8. Heating water leak
  9. Loss of system pressure
  10. Pressure drop in system
  11. Filling pressure outside permitted range causes flashing indication
  12. Low or high system filling pressure
  13. Air in system
  14. Pressure drop below minimum threshold

Where to start

  1. Use Menu → Live Monitor → Water pressure to display current filling pressure
  2. Monitor if pressure drops frequently to identify source of pressure loss
  3. Use Menu → Live Monitor Water pressure to display the filling pressure of the heating installation

The full answer, free

  • 30 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 10), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Vaillant manual for the aroTHERM. Check the model on the data plate before you order parts.

Other Vaillant aroTHERM fault codes