Warning Z1 5374 - Risk of frost in condenser

What does 5374 mean?

This warning appears if the condenser temperature drops below 5°C, indicating a risk of frost damage. It resets automatically if the temperature rises above 7°C.

• Insufficient or no circulation in the heat transfer or heating system.
• Dirt or debris in the system filter/filterball valve SC1.
• Air present in the heat transfer or heating system.
• Defective TC3 sensor (heat carrier out sensor).
• Issues with the installer module or I/O module, or the circulation pump.

Click steps to track your progress.

1. 1

   Check that adjustment valves and radiator thermostats in your heating system are adequately open.

2. 2

   If you can access it, clean the system filter/filterball SC1.

3. 3

   De-air the heating system according to your installation manual and check the water level, filling up if necessary.

4. 4

   If the warning persists, contact a qualified Bosch Heat Pump installer.