Pressure drops immediately when pump shuts off...

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by pktaske, Jul 11, 2019.

  1. pktaske

    pktaske Member

    Joined:
    Dec 9, 2010
    Location:
    New Jersey
    ...and its causing rapid on/off switching.

    Two line above ground jet pump pressurizes to 50 psi without issue. Immediately after it shuts off, the pressure on the head drops to 30ish (see pic). It then immediately kicks in again and shoots to 50, at which point it stops, drops again and restarts. Rinse. Repeat. Lights flicker. Etc.

    What were doing now is shutting the pump off manually after pump pressurized to 50 and turning it on when pressure eventually drops from using water in the house.

    Note that the pressure continues to slowly drop by 1 to 2 psi every 10 minutes. Again, this is only on the pump head gauge. The house keeps pressure fine as there is a check valve in the line going to the house line.

    I'm thinking I've got a leaky check (foot?) valve at the bottom of my well or a leak in the line? But I don't think a simple line leak would cause that immediate 20 psi drop.

    Right now the switch gets a pressure feed from the pump head. A short term fix would be to tap into the water line (after the check valve) and have the switch operate on house pressure hence isolated from the pressure plagued head/well system. I could also leave the switch as is and install a big 1 1/2" check valve in the suction line coming into the pump head.

    I haven't lost prime yet even after the pump being off for 24+ hours. At that point the pump head pressure is showing 0 but when turning on it immediately shoots to 30 psi and pumps quickly to 50 (where of course it again starts to rapidly cycle).

    Think I have this diagnosed correctly?
    Would the above fix work?
    What is long term solution?
     

    Attached Files:

  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Leaky foot valve would explain a slow drop.

    You could a failed pressure tank. That could explain the quick cycling. When you let the water pressure stay at zero, what is the air precharge on the pressure tank? The pressure tank should be empty of water when the water pressure is zero. Knock on the tank or try to move it. Is it empty?
     
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  4. valveman

    valveman Cary Austin Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    The foot valve below the ejector is bad or the leathers are. The fix is down the well, not moving the pressure switch. The only reason you haven't lost prime is there is not air leak up top. It is like holding your finger over a straw of ice tee. The water doesn't drain out, but it goes to zero pressure.
     
  5. pktaske

    pktaske Member

    Joined:
    Dec 9, 2010
    Location:
    New Jersey
    Appreciate your reply. So I used the old pre-existing pressure switch water line that reads read house pressure past the one way flow valve so no more rapid cycling. I'd hate to have to pull the well line out just to replace a foot valve. What's the downside of leaving it as is? My last Gould pump lasted 38 years and probably suffered with the same condition for a while . I installed my new Gould this past Christmas and it was only $520. Will it beat the pump up enough to cut its life significantly? I could also install a spring loaded brass check valve on the inlet line right before where water enters the pump. That would prevent all that back pressure from pulling on any pump mechanisms.

    Thanks.....
     
  6. valveman

    valveman Cary Austin Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    As long as it doesn't lose prime it is good. But if it loses prime it will melt down the pump before you know what is going on. A foot valve would be best, by you can protect the pump from running dry using a Cycle Sensor.
     
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