Grundfos system problem

Discussion in 'Pumps and Tanks Well Forum & Blog' started by vnvet, Aug 2, 2009.

  1. vnvet

    vnvet New Member

    Messages:
    22
    I have possibly two problems with my Grundfos system. First the CU 301 has gone bad, yesterday I lost all water and the CU 301 had no lights lit on the front panel at all, inside one green led is lit and 2 flashing. I called the guy who put the system in and he said a low voltage coil in the CU 301 has gone bad and I need to replace the unit.

    We live in the sticks not near any other water sources to fill buckets so I asked him about bypassing the unit so I could get some water to fill buckets and so on. He told me how to wire the pump directly but cautioned I would have high pressure that could damage things in the house so make sure I had the outside faucets running all the time to keep the pressure down, as long as I did this I could use the system for whatever I needed.

    Here's where I think there may be a second problem. I opened 1 outside faucet and turned the breaker to the pump on, it started slow and in about 45seconds it was at 73 lbs, I turned on my outside sprinkler system and it dropped to about 60 lbs, the longer it ran the more the pressure decreased. After about 15 mins it dropped to 45 lbs, I closed the outside faucet a bit and it increased to about 50 lbs, by the time the sprinlker system had started it's 3rd zone, about 30 mins, I had the outside faucet totally closed and the system would only muster 35 lbs. Does this sound like I have a problem with the pump also? I'd appreciate any help you could give me.
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    This search will show you many others who have had the same problem.

    http://www.terrylove.com/forums/search.php?searchid=2073318

    It doesn't sound like a pump problem. It sounds like your water level in the well is dropping the more water you use, and the lower the water level, the lower the pressure from your pump.

    You can add a pressure switch to make it automatic again, and adding a Cycle Stop Valve will take the place of the CU301, while being much more dependable.

    Here is how I would fix it.

    Attached Files:

  3. vnvet

    vnvet New Member

    Messages:
    22
    Doe's that mean there's a possibility my well can't supply enough water?
  4. Gary Slusser

    Gary Slusser That's all folks!

    I don't know a CU 301 but it sounds like a controller for a variable speed constant pressure pump system. I can't help you get water or figure out what is wrong with the pump operation but, in case you have a bad pump...

    Many of those systems fail as yours has. They are expensive to repair and cost more than a regular pump, small pressure tank and a constant pressure valve called a CSV (Cycle Stop Valve). With a regular pump, CSV and small pressure tank there are no electronics to go bad and a regular pump doesn't run at the extremely high rpm of a variable speed pump that has its rpm constantly being increased or decreased.

    I didn't see the other replies before I replied...

    Yes it means your well may not be able to supply enough water.
    Last edited: Aug 2, 2009
  5. vnvet

    vnvet New Member

    Messages:
    22
    I would think the well should have enough water to run the small sprinkler system I have, there's 8 sprinkler heads per zone and each zone is set for 15 mins, 3 zones. The well was was put in 3 1/2 years ago and the well report says 14 gpm? The well is 240'.
  6. Gary Slusser

    Gary Slusser That's all folks!

    Well if it isn't the well, it's the pump. Or you have a leak. Are you in a drought?

    The recovery rate of the well, 14 gpm, may have reduced for some reason.
  7. vnvet

    vnvet New Member

    Messages:
    22
    I'm pretty confident I don't have a leak, when I shut the pump off and close the faucets the pressure gauge stays at 50 + lbs for hours, until someone opens a faucet.

    I suppose the water table could be lower, we haven't had any rain in 2 months and it's been in the high 90's for the last 2 weeks.
  8. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    You probably just overpumped the well when you had the hose and the sprinkler system on at the same time. Try running the sprinkler zones like normal and see what happens. I think your worst case might be that you need to program in some time between zones for the well to recover.
  9. upper

    upper DIY Senior Member

    Messages:
    154
    Location:
    Fresno, CA
    What kind of sprinkler heads? Upper
  10. vnvet

    vnvet New Member

    Messages:
    22
    They are Hunter MP Rotators.
  11. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    Do you know which nozzles, or how many GPM for each head?
  12. vnvet

    vnvet New Member

    Messages:
    22
    They're MP 1000 nozzles, set at 180 degrees. According to the Hunter chart at 50 psi that would be 24 gph.
  13. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    8 X 24 /60 = 3.2 GPM

    You should be able to run all three zones at the same time. This would only be 9.6 GPM. One zone at a time should not be a problem at 3.2 GPM. You will need something like a Cycle Stop Valve to run less GPM than the pump can produce.
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