(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 11 of 11

Thread: Brand new pump, brand new tank

Hybrid View

  1. #1

    Default Brand new pump, brand new tank

    We just replaced our jet pump and our pressure tank. We set the tank pressure at 18psi, 2 less than pump cut in pressure of 20psi. After the pump runs the tank has 30 to 35 psi. This causes the pump to keep running. Why does the pressure build up by itself?

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    It is probably a little low, not high. Most systems are set to values about 20#'s apart. It turns on at 20 in your case, and shuts off at 40. Putting pressure in the bladder tank keeps the bladder from expanding too much and failing early. The pump provides the energy to compress the air in the tank. The spring in the bladder keeps pressure while the pump rests prior to needing to turn back on at 20 pounds, pushing that stored water out of the tank.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3


    Set the tank at an 18 psi precharge. (Pump off, tank empty).
    After the pump has ran, turn off the power and completely drain the tank. If the pressure still reads 18 psi, you're ok. If it reads higher, you have a problem with the tank.
    With the system pressured up, you will have the same reading at the pressure tank as the reading on the system gauge,

  4. #4


    We drained the tank, pumped 18# into it, turned on the pump,it shut off at 30#, we drained again, it now reads 0#. We turned the pump on with 0# in the tank, and it is now up to 35# and shutting off by itself. This seems great, but later on today after washing clothes and a shower or 2 along with some dishes being done (not at the same time) the pump will not shut off on its own and we have to shut it off at the breaker. We turn it off and on real quick and it just goes off. I do have a theory, because everything is new, Can it be, our well is 35ft deep with about 6ft of water when filled. We have a deepwell jet pump. Maybe we are asking too much of the whole system. IN other words, are we asking this system to supply too much water in too short of a time period?

  5. #5


    Are you reading 0# at the air valve on the tank, or on the system pressure gauge?

  6. #6


    We were reading 0# at both the gauge and the tank valve. When we turned the pump back on it pressured itlself back up to 37# and shut off.


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts