5521 - Bosch Heat Pump Z2 low evaporation JR0 alarm

What does 5521 mean?

This alarm indicates low evaporation pressure (JR0) in Bosch Heat Pump zone 2. It activates after 3 warnings in 3 hours, or if a warning is active for 30 minutes.

• Incorrect combination of Heat Pump and inner part installed.
• Wrong setting of the rotary encoder on a newly installed I/O board.
• Wrong setting of the rotary encoder on a newly installed Installer board.

Click steps to track your progress.

1. 1

   If the Heat Pump or any internal parts were recently replaced, contact your installer to verify the correct component combination.

2. 2

   Ask your installer to check the setting of the rotary encoder on the I/O board and Installer board against the system's wiring diagram.

3. 3

   Reset the Heat Pump by cycling its power at the main breaker.

4. 4

   If the alarm persists, a qualified technician should review the system's internal configurations and installed components.