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Vaillant aroTHERM fault F.723

Building circuit: pressure too low

Heat pump

What it means

If the filling pressure falls below the minimum pressure, the heat pump will be switched off automatically. This fault indicates the building circuit pressure is too low for safe/effective operation.

Likely causes

  1. Water leak in building heating circuit
  2. Water loss or leak in the heating water circuit
  3. Leak in building circuit
  4. Insufficient system pressure
  5. Leak in the heating circuit
  6. Loss of system pressure

Where to start

  1. Check building circuit water pressure via Live Monitor
  2. Inspect for leaks in the heating installation
  3. Inform competent person to top up heating water

The full answer, free

  • 11 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