Grundfos CU200 - Always on

patbobpatbob Registered Users Posts: 1
edited March 2017 in Construction #1
I have a solar setup with a generator backup. CU200 SQFlex with a IO 101 SQFlex Switchbox. 

I recently found the tank overflowing. The CU200 is showing a full tank, is indicating water flow and the power switch is ON. The power switch is unresponsive. It will not shut off. To stop the water pumping I have to shut off the IO 101.

I've checked all the connections. Disconnected the Float Switch. No changes. My take is that the circuit board is fried and I need to buy a new controller.

Does anyone have any suggestions? I'm at a bit of a loss here.

Thanks in advance.


  • BB.BB. Super Moderators, Administrators Posts: 29,043 admin
    I don't have any knowledge about the product--But it sounds like the CU200 is bad.

    I suggest you call the installer (if not you) or Grundfos support.

    Otherwise, check wiring connections / screws / dirty connections--But probably a long shot.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,447 ✭✭✭✭✭
    Maybe it was hit with lightning! They are very reliable if they are protected and installed correctly. They will detect and record over voltage for warranty.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
    E-mail [email protected]

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