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Thread: New Pressure Tank, pressure drops

  1. #1

    New Pressure Tank, pressure drops

    I just installed a new pre-charged pressure tank.

    The bladder went in the old tank.

    Here is my problem: immediately after putting the new tank in, I noticed that the pump was cycling fairly often. I checked for leaks through the house and a hose bibs, and everything is fine.
    I shut the pump off and the pressure gauge dropped from 40 psi to 0 over about 8 hours.

    I can't figure out why. Even though the old tank's bladder was bad, when I charged it with a compressor, the water pressure held fine. Immediately after installing the new tank, I see the pressure drop off.

    Doea anyone have any thoughts on what's possibly occuring or how to test further?

    Thanks for any help.

    Pat

  2. #2
    Pump guy speedbump's Avatar
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    Did you check the pressure in the bladder tank and set it up for your pressure switch settings? If not, read all about bladder tanks on the FAQ's page.

    bob...

    Products and Pricing

  3. #3
    Wow .... thanks Bob for replying so fast. This forum is really nice.

    I didn't check the pressure in the tank because they say it's pre-charged to 38 psi. My switch is on at 20 and off at 40.

    I'm printing out the FAQs now to read tonight. Thanks for the advice.

    I'm just a bit confused as to how the settings on the pressure switch might be related to the pressure dropping to zero when the pump is off. Also, the tank is an Ametrol and is brand new.

    Thank you.


  4. #4
    Pump guy speedbump's Avatar
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    You bought a good tank.

    Your tank can't take in any water until your pump overcomes the precharge pressure in the tank. So with 38 in the tank and the switch shutting off at 40 you only put a few cupfuls of water in the tank.

    I don't know how it went to zero though and stayed there unless the pump was turned off or you have a low pressure cut off switch.

    Products and Pricing

  5. #5
    Bob, thank you again!!

    I'm glad to hear I got ggod tank. It wasn't cheap, so I was hoping I was getting my money's worth.

    The gauge went to zero when I had shut the pump off overnight to try to figure out what was wrong.

    When the pump is powered up the gauge drops to 20 psi then the pump starts again, and runs to the gauge hits 40 psi About a minute or so of pump run.

    If I understand your response above (I'm a real novice at this), the pre-charge is 38, and the cut-off is 40, so the pump is only running long enough to pump in a small volume of water, then stopping at 40?

    If I understand, should I reset the pressure switch to 50/30 or is it better to bleed some air from the tank, say to 30 psi charge?

    Best regards,

    Pat

  6. #6
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    For 20/40 psi on the switch you need 19-18 psi air pressure with no water in the tank.

    You sure you don't have a leak? Shut off the water to the house past the tank and watch the gauge for some time. If the pressure falls, you have a leak between the tank and the pump's inlet in the well. Usually it will be a foot or check valve.

    I see we were both posting at the same time... With the pump off overnight, water use could have reduced the pressure to zero.

    Gary
    Quality Water Associates
    www.qualitywaterassociates.com
    Softener Forum

  7. #7
    Thank you Gary, and again thank you Bob.

    If I may, ley me ask again:
    The gauge went to zero when I had shut the pump off overnight to try to figure out what was wrong.

    When the pump is powered up the gauge drops to 20 psi then the pump starts again, and runs to the gauge hits 40 psi About a minute or so of pump run.

    If I understand your response above (I'm a real novice at this), the pre-charge is 38, and the cut-off is 40, so the pump is only running long enough to pump in a small volume of water, then stopping at 40?

    Also,if I understand, I either reset the pressure switch to 50/30 or bleed some air from the tank, say to 18-19 psi as Gary says? (it seems that I would want to set the pressure switch to handle the 38 psi precharge rather than lower the precharge pressure if I understand the FAQs)

    Thank you guys!

    Pat


  8. #8
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    For good water pressure you want to set the pressure switch higher. The first number is the cut in pressure and the second the cut out pressure. So in your present system it turns the pump on when the pressure reaches 20# and then turns the pump off at 40#. In any system you want the air pressure in the tank at about 2# LESS than the cut in pressure, in this case 18#. This will then keep 18# of pressure on the water in the system with the pump off.
    However 18-20# is rather low. I would re-adjust your pressure switch to 30-50 or 40-60. Then set the tank's air pressure 2# below the cut in pressure either 28 or 38#.
    Your other problem is you probably have a small leak in the well that is allowing you to lose pressure. The system will act the same as if you have a faucet slightly open. You need to fix it.
    Once the leak is fixed and the air pressure in the tank is set to the proper pressure for the setting of the pressure switch you should be good to go except I would install a CSV, Cycle Stop Valve which will give you a more constant pressure and help your pump and new expensive tank last longer.

  9. #9
    Pump guy speedbump's Avatar
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    I think you have a submersible pump, right? If so, it shouldn't take 1 minute to put less than a gallon in that tank. Since your tank is at 38# now and your switch is set to turn the pump off at 40, the tank doesn't even take in any water until it overcomes 38#.

    bob...

    Products and Pricing

  10. #10
    Thank you Bob,

    Would there be any explanation for the pump taking a minute to go to 40? Wouldn't it be adding water starting at 20? If I'm thinking right, the pump comes on at 20, runs to 40, and is filling the entire time? Maybe I'm not understanding what happens at 20 psi, and then what happens when it reaches 38 psi.

    Thank you,

    Pat

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