Pump will not reach high enough pressure

Discussion in 'Pumps and Tanks Well Forum & Blog' started by billp, Feb 15, 2007.

  1. billp

    billp New Member

    Messages:
    5
    Pump will not reach high enough pressure

    I have a deep well submersible 2 HP pump with a bladder type pressure tank, 30-50 psi switch. Switch, tank, etc are all in warm crawlspace. I don't know the exact depth of the well, but at least three hundred feet.

    This system has worked flawlessly for years, so not an installation issue.

    Yesterday we awoke to no water. The pump was not running. I hit the overload reset switch and the pump came on. (I had never had to do this before). I think the pump had been runnning for a while, perhaps overnight.

    Pump ran fine but will not bring pressure above about 34 psi. Thus pump will not turn off. And it takes a long time to move the pressure at all; with pipes full, going from 28 - 34 psi takes over 20 minutes. (Typically, pump would have increased pressure from 28 to ~50 psi in a few minutes). Lots of pipe in the house (2 kitchens, 4 baths, 2 large water treatment tanks) so I realize it takes a while to fill everything, but even if I close the house side valve and just let the pump pressure up the pressure tank, that takes a long time too. (It will quickly get the pressure up to the air pressure level in the tank, i.e. 28 psi, but it is slow beyond that).

    Checked pressure in tanks (after releasing water pressure, etc) and they were low, about 14 psi. Don't know how long this had been the case, since I had never checked them. Refilled to 28 psi. With pipes full, pump off and water line on house side open, tanks hold pressure, indicating no leak on house side.

    Did not know quite how to check to see whether pump is getting the right voltage. Voltage coming in to the box is fine. The pump side has has three wires, red, black, yellow. Voltage R-B is 220, R-Y is 220, BY is 280 (?).

    Turned off pump, closed valve on house side but left valve on well side open, pressure held steady for over an hour. (meaning no leak on the well side?)

    Weather has been very cold, with nighttime temperatures below freezing for over two weeks, which is very unusual for Virginia. In the cement casing around the well head, there are some PVC pipes that are above the ground, but no leaks at all are visible.

    Any ideas? Pump going bad? Some kind of leak inside the well? I don't know much about what I have, e.g. check valves, foot valve, pitless adapter, etc.

    Any help would be appreciated, and apologies if I've left out something important.
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Symptoms suggest a leak in the pipe from the pump.

    The overload switch had operated, which indicates too much current (Amps), which is related to too much water being pumped, or to some drag in the motor/pump system.

    If there was so much drag that the speed was pulled down, then it should have tripped the overload quite quickly.

    I suspect that you may have a supplemental check valve (the pump probably has one also) somewhere above the pump, either inside or in the line somewhere. That would hold the pressure in the tank.

    I also suspect that you may have a break in the pipe below that supplemental check valve. That break is discharging the capacity of the pump at lower pressure so you aren't getting the usual pressure at your tank.

    Further diagnosis:
    1. Search for another check valve.
    2. Measure Amps on the pump while running and compare with specified Amps for the motor. You will need a clamp-on ammeter. Amps greater than the motor rating says the pump is pumping a lot of water but that it is not getting to the tank. Low Amps suggests that the pump has lost a stage or impeller diameter and is not delivering the required head and flow.
  3. billp

    billp New Member

    Messages:
    5
    current draw

    Bob:
    Thanks very much for your reply.

    Check valve: There is no check valve near the tank. However, I'm pretty sure there is one at the top of the wellhead.

    I measured amps, here is what I got:

    Amp draw on line going in to box: 10.5

    Measuring individual pump side wires here is what I get:

    Black wire only: 10.5
    Red wire only: 2.5
    Yellow only: 8
    Red+Black: 12

    The box specs say that the pump is 10 amps, with a "S.F. Max" of 13.2 amps.

    Two questions:
    1. Does this still sound like a break in the pipe somewhere below the check valve?
    2. Right now until we get this fixed I have the pump off, but turn it on every 5 hours or so for about 30 minutes to get some water in the house for toilets, etc. Is that too long to let it run? Am I doing some damage? With all the ice on the ground I don't know when I can get someone out here to fix this, and was hoping we could get by running the pump now and then.

    Thanks!
  4. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    http://www.goulds.com/pdf/GSSINGLE.pdf

    The amps seem to be off from the expected values in the document at the link, which are Yellow 13.2, Black 11.9, and Red 2.6; compared to your 8, 10.5, 2.5 for the same wires.

    If the amps are low, that is an indication of loss of capability of the pump, resulting in less flow and therefore less power. The fact that the yellow is less than the black could be a problem or it could be that someone mismatched the wires.

    The motor certainly doesn't seem to be overloaded.

    As for running time, there is no point in letting it run after the pressure reaches maximum.

    Maybe someone else has some ideas from their greater experience.


    Another possibility could be that something in your control box is causing a problem, although I can't figure out what it might be. (Added by edit; Feb 16th)
    Last edited: Feb 16, 2007
  5. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    The amperage readings you are getting are for a 2 hp motor that is not working very hard. In other words it's not pumping much water. You said you thought it may have ran for a long time. I'm not sure why you think this, but if it's the case you may have nuked a few impellers in the pump end. That would explain the slow production and the low pressure. The fact that the box tripped usually means the motor was laboring for some reason or it couldn't start. Since it started up for you, I assume the second reason won't apply. I would just use the pump while your using water, like BobNH said, letting it run to max pressure isn't doing you or the pump any good.

    bob...
  6. MaxBlack

    MaxBlack Member

    Messages:
    66
    Location:
    TX Hill Country
    Any chance at all that your well is running dry/low? Is there any different in the quality of the water that it's bringing-up?
  7. billp

    billp New Member

    Messages:
    5
    Bob:
    Thanks for the gould link. I went back and retested the current draw; the yellow wire was in fact 13, my bad.
    Pump guys came today. They pulled the cap and there was water on the top of the pipe (no pitless adapter), indicating that the pipe is good, at least down to the next checkvalve, assuming there is one (or more than one). It looks like the pipe may be galvanized, and with a 2HP pump we are guessing the well is a few hundred feet deep, at least, so it will take a week or more until the ice melts for them to be able to get a truck near the wellhead (it's on a steep hill) to fix it.
    Even though the motor might be okay I'm thinking I will have then entire pump and motor replaced, as well as any of the galvanized pipe (or all of it) while this is going on.
    Any other ideas on what else I should have done during all this?
    Thanks.
  8. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    If your galvanized pipe has holes in it, you should be looking at Poly Pipe or Sch 80 or 120. That won't rust through. And electrolisys won't mess with it either. There really shouldn't be any check valves in the line except the one in the pump.

    bob...
  9. billp

    billp New Member

    Messages:
    5
    Thanks. What are the pros and cons of galvanized vs. poly? The pump guy says they would recommend galvanized, but I haven't had a chance to ask them why yet. I want to get the 'right' one, it is not a cost issue, since the big $$ will be the labor, not the parts.
  10. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I have always preferred galvanized. But, if your water is eating holes in your pipe, plastic is the way to go. Galvanized will be the most expensive for sure.

    bob...
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