Error 121 - HC1 flow temperature too low

What does 121 mean?

The user interface displays '121: HC1 flow temperature too low', indicating that the flow temperature for Heating Circuit 1 is below the set threshold. This suggests insufficient heat delivery. This error typically triggers an automatic reset.

• Insufficient heat generation by the heat pump for HC1.
• Poor water circulation in HC1 due to closed valves or blockages.
• Air trapped in the heating circuit.

Click steps to track your progress.

1. 1

   Turn off the main power supply to the heat pump for 30 seconds, then turn it back on.

2. 2

   Check the water pressure in Heating Circuit 1 and ensure all relevant valves are fully open.

3. 3

   Allow time for the automatic reset to occur (default 6 hours) or use the manual reset function (Line 6711) if available.

4. 4

   Contact a qualified service technician to diagnose the low flow temperature issue.