5518 - Bosch Heat Pump Z2 condensing temperature outside envelope warning

What does 5518 mean?

This warning indicates that the condensing temperature in Bosch Heat Pump zone 2 is outside its highest permitted range. It triggers if the temperature on sensor PH1 is above the highest permitted actual envelope for longer than 30 seconds.

• Evaporation temperature is too low in relation to the condensing temperature, likely due to low outdoor temperature.
• Incorrect flow rate (too high or too low delta) in the heating system.
• Blocked or low air flow to the air heat exchanger on the Heat Pump.

Click steps to track your progress.

1. 1

   Check the current outdoor temperature; extremely low temperatures can affect the system's performance.

2. 2

   Review your heating system's flow and temperature settings and adjust them if necessary to ensure proper operation.

3. 3

   Ensure adequate air flow over the air heat exchanger on the Heat Pump by clearing any obstructions like leaves or debris.