Do 200 feet of water above the 1.5 HP pump help the pump push 540 feet head up?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by rreeuuvveenn, Apr 17, 2014.

  1. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california
    according to Grundfos, the size of the pump is at the top limit of its capability,

    My real question is,can i lower the under current setting to 50% below the nominal current,

    cause the water column above the help the pump to up,

    Does it make sense?


    thanks a lot for this forum,

    reuven
  2. Reach4

    Reach4 Active Member

    Messages:
    2,303
    Location:
    IL
    You could have worded it better.

    I don't understand your "real question". It seems to ask about how to cut the pump current in half.

    Regarding the title, the head the pump deals with is the distance from the top of the water to the top plus the head from the topside water pressure plus a little frictional loss. So the head the pump deals with is based on the water level rather than the pump depth.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,003
    Location:
    NW Ontario, Canada
    None of it makes sense to me except the title and Reach4 already answered that. More info may help.
    Model of pump?
    Model of controller?
    What is your intention?
  4. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california
    sorry for the bad presentation,

    Pump 1.5 HP three phase Grundfos 4" 10S15-21 540 feet in a 6" pipe, installed 2008,feed pipe sec. 120, SS fittings,

    when pumping air in the 1/4 tube,shows 80-105 psi=180-230 feet of water above the pump,

    controller Motor Saver 777-LR, made by Symcom, 16 years old,

    normal amperage 6.9 amps, under current set is 5.5 amps,

    Is the pressure 180 psi at the intake of the pump helps the pump? And that is the reason it uses less amps? So it does need to pump the water that hard?

    So I can set the UC to 3-4 amps?

    Does it makes sense?

    thanks for your help,
    Last edited: Apr 18, 2014
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,003
    Location:
    NW Ontario, Canada
    OK so now we know what your intention is but we still don't know why you want to set it so low. Is it tripping out too soon with water still left in the well? I don't know the pump curve for that model but think you risk deadheading the pump if you set it too low.
  6. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california
    right,

    it pumps water, start at 6 gpm slows down to 2 gpm goes to under current, in 15-25 minutes,

    water level is still high, 180 feet to 220 feet,

    pump is at the top off the curve,

    this performance fits Grundfos curve, at 540 feed down it is at its limit,

    My inexperience thinking. The 90 psi pressure at the inlet of the pump, helps it...?True or false?

    trying my best before lifting the pump 40 feet,or changing the pump to 2 HP,

    bottom line, 200 feet of water in the wall, and UC is kicking in, why why why why....
  7. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,003
    Location:
    NW Ontario, Canada
    Lifting the pump won't help. It is all based on the height above the water, not the depth below the water. That pump is too far off the curve. http://ca.grundfos.com/content/dam/GCA/Data Sheets/SP 4 Inch/Model 10S.pdf

    2 GPM is probably the minimum required for motor cooling, depending on if the pump is in the rock bore (size?), in the 6" casing or the motor is in a cooling sleeve.

    What is the water level when it pumps at 6 GPM before it drops to around 200 feet above the pump? What is the PSI at the tank when the flow drops to 2 GPM?

    A higher head pump might not buy you too much more runtime if the well recovery is low. Pumping into a non-pressurized storage tank may be your best option.
  8. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california




    Thanks for your response,

    here is what i can see,
    The pump is pumping water into a non -pressurized storage tank,

    The water level drops around 40 feet of water to 180 ABOVE the pump, when the flow drops to 2 gpm(more or less), after 10-20 minutes,goes into under current, stops pumping

    My BIG PUZZEL IS, 85psi at the INLET of the pump, that helps to pump 240 psi in order to get the

    water into the tank,

    Does that 85 psi COUSE the pump to draw less amperage,???????
  9. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,208
    Location:
    Houston, TX

    On earth, yes the pressure and how deep the pump is under water will change the power required to bring it to the top of the well. Less current for less work.


    If that is what you were asking, I believe that is how the Theory works.
    Last edited: Apr 19, 2014
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,473
    Location:
    Lubbock, Texas
    As the water level drops the production of the pump decreases and the amps are reduced. It is safe for that pump to work as low as 1 GPM. But you will need an underload device or Dry Run relay that can be adjusted where you want to make that happen. A Cycle Sensor can be adjusted to let the pump work at 1 GPM, but it will still know the difference and shut the pump off when flow goes to zero.

    [​IMG]
  11. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california
    Thanks so much for the replays,

    I did put the cycle sensor on one pump, and it works good, tank is full, and drought is on,ran is off,

    My problem with the 540 feet deep well is,the 1/4" air tube, indicates 90 psi +/-20psi,

    which means plenty of water, sensor (777-LR) say UC at 4.5 amp,

    Need to verify the real level of the water, maybe lifting the pump 1" ?

    and lower a string into the deep well( scary...)

    or try a new cycle sensor(the excisting one 15 years old,

    any comments
  12. Reach4

    Reach4 Active Member

    Messages:
    2,303
    Location:
    IL
    The air pressure measurement method is reliable.

    I think you are asking if it is OK to drop the current at which your cycle sensor cuts off the pump so that you are not tripping out. Maybe you should try a clamp-on ammeter to measure your current.
  13. valveman

    valveman Moderator Staff Member

    Messages:
    4,473
    Location:
    Lubbock, Texas
    As long as you are pumping at least 1 GPM the pump will be fine no matter how low the amps go. You just need to be able to set the Dry Run amp setting below the amperage the pump draws while only pumping 1 GPM.
  14. rreeuuvveenn

    rreeuuvveenn New Member

    Messages:
    12
    Location:
    california
    Thanks for your kind help,

    the pump saver(777-LR) shows the same as the clam-on meter,

    will try and observe a lower Under current sating,

    thanks so much,

    reuven
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