I have a well water system with a submersible pump 1/2 horse with 1 1/4 black water line with a check valve just above the pump approximately 120feet below top of well casing and a bleed back fitting 10 feet from the top of well casing out of the water so system can be drained for seasonal use. Then from well casing into house to expansion tank is about 40 feet long with another check valve on the inlet side of expansion tank with a snifter fitting. The expansion tank is 38.1 gallons pressure switch is 30/50. I bled air out of the expansion tank setting it at 25-28 psi below cut in pressure which is 30 psi. The issue I’m having is that once the pressure switch shuts off at 50 psi . The system will run when calling for water kicks on and shuts off at the30/50 but hours later or periodically even after kicking off at it’s required psi which is 50. Pressure suddenly starts to get increase from 50 psi to 80 plus in return blows off pressure relief valve. Any suggestions on what may be happening

  • This is very hard to follow. Some formatting (hit <enter> twice for line brakes, look at the formatting tips to the right of the edit question dialog box) would help immensely. Including a drawing or pictures would also help.
    – FreeMan
    Jul 25, 2022 at 16:56

1 Answer 1


Would replace the pressure switch.

Possible the contacts have pitted and stick together instead of releasing at the right pressure.

Turn off the power, drain the tank, remove the old switch and replace with the new one.

  • Well this is all brand new parts new pressure switch and everything system is only 2 months old. Not that it can’t be faulty I’m just wondering if it could possibly be a water logged expansion tank . What r some ways to double check to find out for sure if it’s pressure switch.
    – Jamie fox
    Jul 25, 2022 at 13:50
  • @Jamiefox A water logged tank would only make the pressure switch cut in and out repeatedly, on and off all the time the water was running/in use. This can wear out the contacts very fast. When using the water, does the pump stay off for some time till the pressure drops, or does it kick in right away and act like a yoyo?
    – crip659
    Jul 25, 2022 at 14:09
  • I think both may be the issue I’m draining the water completely from the system going to get a new pressure switch, and add air to the bladder set to 28 psi . Then recharge system. Customer said pump kept kicking on and off while taking a shower I’ll lyk what happens thank you for your input it’s greatly appreciated I will get back with you in a few
    – Jamie fox
    Jul 25, 2022 at 14:38
  • 1
    It's clearly a defective pressure switch, whether or not the tank is waterlogged. If the switch is not OFF at 50, it's defective. Can't get to 80 without a defect. If you have "customers" and don't know how to check for a waterlogged tank I pity your customers. Run tank to 50 with no water use, drain into a bucket until pump kicks on, measure the water in the bucket, compare to tank chart. If you drain the system (water pressure 0) and the bladder pressure isn't where you left it the previous time, you can bet the bladder is bad unless someone else adjusted it.
    – Ecnerwal
    Jul 25, 2022 at 14:43
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    Snifter fitting - is this a no-bladder olde-fashioned tank? There's a reason they are out of fashion. Those, you have to drain out the water from when they get waterlogged, and the snifter is the prime suspect for waterlogging, but that still won't bump the pressure up 30 PSI from the cut-out. Drawdown volume and tank chart still apply, but the tank chart will be a different one.
    – Ecnerwal
    Jul 25, 2022 at 14:49

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