Grundfos CU200 - Always on

patbobpatbob Posts: 1Registered Users
edited March 10 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. Posts: 26,088Super Moderators 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
  • adrian82adrian82 Posts: 2Registered Users
    Must of blown a capacitor Interesting to hear that. huh, unless you have the time and tools - consider a new unit. Perhaps not another CU200. Reach out to the company.
    Somewhere in Arizona - 3.5kw / :) 
  • Dave AngeliniDave Angelini Posts: 2,930Solar Expert ✭✭✭✭
    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

Sign In or Register to comment.