Question: I have a Magna 3 that often surges and cannot figure out what is the cause?
Answer: The most common reason for a Magna surging is do to the pump being incorrectly wired. Check to see if the power is being cycled on and off. As shown in the diagram below, the motor is to be continuously powered and enabled to run through the digital input.
If the wiring is not the issue, check to see that the system has enough pressure to run the pump. Another factor is to verify that each pump has a check valve on the discharge. If not, the surging pump could be receiving flow from the redundant one.
If none of these solutions work, contact your local Grundfos wholesaler for additional troubleshooting support.