Alarm 51 — Blocked pump, pump stops and tries to restart

What does Alarm 51 mean?

The pump has detected that its rotor is blocked, causing it to stop operation. It will automatically attempt to restart. This can happen if the pump has been inactive for a long time.

• Rotor is physically blocked by debris or sediment.
• Pump seizing up after extended periods of being turned off.

Click steps to track your progress.

1. 1

   Turn off the pump and disconnect power to ensure safety.

2. 2

   Inspect the pump's rotor for any physical blockages or impurities, and clear them if found.

3. 3

   Manually try to turn the rotor to ensure it moves freely; sometimes, a pump can seize up if idle for a long time.

4. 4

   If the error persists after checking and clearing any blockages, contact Grundfos Service.