well pressure

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    • #277898

      I don’t know if this question is appropriate for this forum, but… I have a deep water well (single family residence) with a pressure tank. The pump shuts off properly at the high pressure setting (~50psi) and turns on at the low pressure setting (~20psi). But, immediately after the pump turns on (relay contacts close) the system loses all pressure for a period of 1 to 10 seconds. Then the water comes back on as the pressure is restored (20psi) and starts to build normally. What might cause this?

    • #297338

      Sounds a whole lot to me like the foot valve ( non return valve ) on the line feeding the pump from the tank is leaking and allowing the water to flow backwards back down the well until the pump’s suction or pressure overcomes it then things get back to normal until the next time. If this turns out to be the case then it is likely you need to replace a faulty non return valve to overcome the problem.

      Selgas Services Ltd
      Craftsman Gasfitters, Plumbers, Electrical Service Technicians

    • #297339

      I my opinion it is probably the air pressure in the tank. If it is a captive air tank or bladder tank it shoud have 2 PSI less than the switch cut in pressure. 20 psi cut in on the switch should have 18 psi in tank with no water pressure. Another common thing is the pipe nipple between the switch and the system corrodes shut causing a dely between the time the system pressure drops and the switch senses it. Hope this helps.

    • #297340

      Sorry for the delay; I’ve been procrastinating .

      Peter, where is the foot valve, usually? If it’s in the piping from the wellhead, how does one recognize it? Would it ever be put in the ground??? (and impossible to locate…..) If in the well itself, is that a major (near $thousands???) cost to replace?

      Paidpiper-1: does this mean the tank has a ambient pressure (no water) of 18psi? [Curious, does a captive air tank need to be air charged after it’s installed and some water put in??] In normal operation what’s the effect of changing the pressure switch settings, say to come on at 35psi, or 10psi? If there was a leakage/pressure loss in the air chamber (I’m sure I have a bladder tank) would that 1) cause the water pressure to build up a slowly at first then very quickly toward the end, and 2) cause the pressure to drop fast with use after the pump shuts off? Also, I can’t quite picture how this scenario would cause my problem?

      Paidpiper-2: Is the nipple a more likely place for corrosion? [We have extremely hard water (~70 GPG — hill country of central Texas) and (I think) the tank and switch is before the water conditioner/softener.] But that connection nipple looks maybe 1″. I’m having trouple picturing this, too. The anamoly in my mind is the fact that the pump comes on appropriately according to the pressure guage on the switch, and then (after the pump turns on) is when I lose inside water pressure for 1-10 seconds. Could you indulge my ignorance a little more ? Thanks.

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