Pressure tank - Obstruction?? Help Please!

Discussion in 'Pumps and Tanks Well Forum & Blog' started by davegeiger, Jul 22, 2007.

  1. davegeiger

    davegeiger New Member

    Messages:
    8
    I have a well/pressure tank system which is showing most of the signs of a bad pressure tank (very short cycling), BUT with a big difference. When I try to drain the tank (with the power off and the valve to the house closed), there is a spurt of water, then the pressure gauge drops to zero and the flow stops completely. The pressure in the tank is still mid to high 40's (measured with an air gauge on the tank), but nothing comes out of the valve. If I turn the pump back on at this point, it runs momentarily, the pressure gauge returns to just under 50, and the pump shuts off again.

    If I try the same procedure with the valve to the house left open, the water will run for longer, then the gauge will drop to zero and the flow will stop. I think the longer flow is because water is draining back from the pipes. When I turn the breaker back on, the pump will run for a few seconds (maybe 10) until the pressure gauge reaches 50, then shut off. I think it runs longer in this case because it is re-pressurizing the house plumbing.

    I think what all this means is that something has blocked the flow between the pressure tank and the valve and pressure switch. Can anyone see a different explanation?

    If this is the case, it means I can't release the pressure in the tank, so I can't drain it. Trying to replace it while under pressure would be a real nightmare. Any suggestions?

    Thanks
    Last edited: Jul 22, 2007
  2. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Step one: turn pump off
    Step two: open tap until flow stops
    Step three: measure air pressure in tank
    Step four: if air pressure is greater than 28 psi, bleed off excess air until pressure is 28 psi
    Step five: return system to normal service
  3. davegeiger

    davegeiger New Member

    Messages:
    8
    Clarification

    Thanks CHH, but I'm not sure I made the problem clear. I'm pretty sure that the tank is maintaining pressure at or near 50 PSI. Both my pressure gauge and the action of the pressure switch seem to confirm this. If I attempt your solution, then I will be re-filling the bladder while there is still pressure in the tank. The manufacturer's directions say not to do this.

    In addition to the gauges and the original post, there are some other reasons that I believe the pressure in the tank is near the upper cut-off.

    - The tank is fairrly full of water
    - I know the bladder had 28 lbs. of pressure when the tank was installed. I watched the well guy check it. I know no one has added air. The only way I can see for for the pressure in the bladder to be greater than 28psi is if there is pressure from the water in the tank.

    Maybe I'm not understanding why you believe draining off air pressure would solve my problem. Would you be willing to offer a little more explanation ?

    Thanks
  4. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    You said that the tank had 40 psi measuring with an air gauge. I am assuming that you are measuring the air pressure in the bladder. Where exactly is this measurement being taken?
  5. davegeiger

    davegeiger New Member

    Messages:
    8
    Sorry for the confusion. Its a standard installation with a pressure gauge and a pressure switch. I also measured the pressure of the tank with an air gauge.

    Starting from the point where the power is on and the installed pressure gauge is at or near the upper cut-off. I turned the power off and tried to drain the tank. There was a short spurt of water, then the flow stopped. At the same time, the installed pressure gauge dropped to zero. From the force of the "spurt", I am fairly sure the pressure in the tank was good. The pressure did not taper off slowly, but cut off pretty abruptly. At that point, I used an air pressure gauge on the tank and it showed high 40's. Since I am sure that the air pressure in the bladder was not that high, I believe the pressure beyond 28psi must be created by the water in the tank.

    When I turn the power on, the pump runs for a second or less, and the installed gauge jumps back up to 50 psi. The performance of the pressure switch and the installed pressure gauge are in agreement (when the gauge shows zero, the pump runs - when the gauge shows 50 the switch cuts off.) It's hard for me to believe they would both fail at once. Something blocking water so that it does not come out of the pressure tank is the only other explanation I can come up with.
  6. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Ok, there are a couple things to think about.

    If there is a blockage then it's likely the tank will have to be R&R'd. At the very least the tank will have to be removed from the system.

    You don't want to disassemble a system with pressure on it (as you mentioned).

    With those things in mind, you'll still have to bleed the air from the bladder. Follow the steps I posted up to step four and note anything unusual when bleeding air from the system. By anything unusual I mean *anything* other than air moving through the Schrader valve or any unusual noises.

    Report results after step four. Do not reenergize the pump.

    As a side note: I'm assuming that nothing "crazy" has been done with the plumbing. Pictures would be nice.
  7. davegeiger

    davegeiger New Member

    Messages:
    8
    Thanks CHH. I did go ahead and start bleeding the air under the assumption (as you said) that the d**n thing didn't work anyway, so what could I hurt. I only took it down by about 5 psi then repeated the entire test. Wonder of wonders, things were much improved. The pressure guage would still drop suddenly to zero, but it took much longer and there was a tapering off before the shut off. Flushed with success, I drained the tank until it dropped to zero again, bled the air pressure to 28psi, turned the pump back on, and now all seems well.

    What I'm now thinking happened is that air has been somehow accumulating in the tank. I guess it would have to come from the pump. I certainly haven't added any and I don't think if could leak "in". Anyway, if the tank was essentially full of air, that woudl explain the results I was getting. Unfortunately, if this is the case, I now have a tank with a nearly empty bladder and a large air pocket. Workable I guess in the same fashion as a pre-bladder tank, but certainly not ideal. Does that make sense? I can't come up with any other explanation.

    One other thing I found in this process, was that the cut offs are set at 25 and 45, not 30 and 50. That means the air pressure in the bladder as it was originally set exceeded the bottom cut off. I tried to figure out what the result of that would be, but my head started hurting and I decided to be done for the day.

    Thanks again for your help Greatly Appreciated!

    Dave
  8. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Glad it worked out. Air pressure in the tank should be 2 psi below the low cut-off (if I remember correctly).

    As for the change in air pressure, maybe it's just the result of seasonal temperature changes if the tank is fairly exposed to ambient temperatures. If the tank was installed in December and it was cold, say 40 degrees on average, and now it's much warmer, say 60 degrees, then the air pressure change would be due entirely to temperature.
  9. davegeiger

    davegeiger New Member

    Messages:
    8
    Tank's in the basement, so not more than about a 10 degree swing.
  10. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Ok, so the temperature explanation goes down in flames.

    After you drained the water from the tank and then reduced the air pressure in the tank to 28 psi it should be in original "as installed" condition.

    The only possible problem that I can see is if the bladder leaks and there is now water on the air side of the bladder. That would have caused the increased air pressure. A leaking bladder is a not fun and I had bugs growing in my system before I replaced the tank.
  11. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    very small hole in the bladder letting pressure leak above the wet side. Went through this with a friend of mine recently. If you discharge the bladder to zero through the air valve when you get close to all air being let out of the dry side of the bladder, then I will bet that you will see water start to come out of the air valve. My bud's begain showing water just as the air was almost all out.
  12. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    If water won't come out of the water fitting on the bottom of the tank, but the tank still has pressure in it and is still full or nearly full of water like you stated, it's just like abikerboy stated. A hole in the bladder and water has gotten above the bladder. The bladder still comes down to the bottom of the tank and covers the water port at the bottom preventing anymore water from coming out.

    The tank is bad and should be replaced or you will be experiencing the same problem in the near future and doing damage to your pump motor.

    bob...
Similar Threads: Pressure tank
Forum Title Date
Pumps and Tanks Well Forum & Blog tank pressure problems Jul 17, 2014
Pumps and Tanks Well Forum & Blog Tankless Submersible Well Pump losing pressure Jul 7, 2014
Pumps and Tanks Well Forum & Blog Information on Distance between Pump Pressure Switch and Pressure Tank Jun 16, 2014
Pumps and Tanks Well Forum & Blog Looking for some help and education on well pressure tank May 26, 2014
Pumps and Tanks Well Forum & Blog Do I need a well pressure tank? May 20, 2014

Share This Page