Wish I could boost my water pressure

Discussion in 'Pumps and Tanks Well Forum & Blog' started by lammr, Apr 26, 2006.

  1. lammr

    lammr New Member

    Messages:
    4
    I am on a well system with a submersible pump out at the well feeding a 20 gallon Challanger Series pressure tank controlled by a Square D FSG2 40/60 pressure switch both located in the basement. Our house was built about 2 years ago so it is all pretty new. Everything works as it did from day 1 with constant water pressure but the overall pressure has always a bit on the low side. My garden hose will barely run an oscillating sprinkler, and only one at a time. I should probably spring for a pressure gauge so I can know exactly what my tap pressures are as I am not sure how different they might be when compared to the tank pressure gauge. My question is: can I raise my system pressure by adjusting the pressure switch or should I leave well enough alone? I am not even going to try and contact the original plumber anymore (frustraiting to leave a message and never get it returned.. guess we are already money in his pocket), so I am going with the assumption that the plumber installed and adjusted everything according to "normal" specifications.
    I think I have a basic understanding. My system pressure should fluctuate between 40 and 60 psi. When the pressure tank is full, it will be 60psi, then during water use drop to 40psi at which the pump will kick on, pump water into the pressure tank until it expands the diagphram enough to reach 60 psi, then cut off. It looks like it is doing this as best I can tell by watching the gauge after the pressure switch. What confuses me is the cut-in and cut-out adjustments. Which one would you adjust to raise your overall water pressure and is there a methodical way to do it properly? All the literature and information I have found so far is pretty vague and I am terrified of messing something up and making matters worse.

    Any Ideas?

    Thanks!

    -Mike
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    http://www.goulds.com/pdf/TTECHWP.pdf

    For switch adjustment instructions, go to page 36 in the manual at the link above. It will probably show as page 38 in Adobe Acrobat Reader but 36 on the printed page.

    Any properly selected submersible should be able to give you all the pressure you need. On the other hand, if he had a pump to get rid of that didn't quite meet your requirements, then you may have a problem.
  3. lammr

    lammr New Member

    Messages:
    4
    Hummm

    Thanks for the info. I had found that pdf on a previous post, but it didn't make much sense to a plumbing novice like me. I wish it had a step-by-step procedure for reaching a desired system pressure. Lemme see if I understand then... If I turn the larger center nut down, it raises the cut-in point but doesn't change the differential, and essentally raises your effective system pressure by X psi (1psi each 1/4 turn?). So rather than being 40/60, I might get 50/70? If I turn down the smaller nut to the side, it raises the cut-out point and changes the differential. So rather than being 40/60, I might get 50/60? I am guessing I should leave the differential adjustment alone then as a 20psi spread seems the norm.

    Is it really that simple? Crank down a quarter of a turn on the cut-in adjustment and increase your system pressure 1psi? What is the limit I should not exceed? I guess first off, I need to accurately measure what limits I have now rather than assuming it is 40/60.

    I certainly hope the original plumber didn't short us on the pump! I am not sure how I could even prove that. I am hoping he just left the system adjusted on the low side to try and save water or something.

    Again, thanks for the help and sorry if I am a bit thick where plumbing is concerned!!

    -Mike
  4. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    You will also need a tire gauge to check the precharge pressure in the bladder tank. Maybe not now, but eventually.

    If you are getting 40 to 60 psi and no flow out of the sprinkler, you may not have an accurate gauge. But try the pressure switch first.

    At some point you will want to check the capacity of your pump. It may not be able to keep up with the sprinkler.

    Can you find any information on the pump or well? If you can find the model number, it is possible to find the pressure/flow characteristics.
  5. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Your precharge pressure should be 1-2 #s below your cut in pressure. To check it releave all pressure in the system by turning off the pump and opening a valve until the water stops flowing and then check the bladder pressure.
  6. lammr

    lammr New Member

    Messages:
    4
    Update

    Well, I investigated things a bit more last night. The cut-in point was set to 35psi and the cut-out point at 55psi. I left the water running and watched a few times to be sure. So I gradually cranked down on the cut-in nut until I got it up to 40/60. Not sure if I notice much of a difference in water pressure adding 5psi, but I feel much more confident about adjusting it. My question now is... how far can I take it? What is the acceptable limit for my challanger series pressure tank and FSG2 switch? Could I reliably get away with 50/70... 60/80? Or will that work my sub pump too much? Is it possible to measure the flow rate of my pump by timing the time it takes to fill the tank after the cut-in trips?

    Cass... I also did what you were saying... I turned off the power to the switch and let the tank drain. The pressure on the gauge went to zero. When you are talking about bladder pressure, you mean the air pressure in the tank that you would check via the "tire" valve stem? What exactly is "precharge pressure"?

    Thanks for all the good info fellows!

    -Mike
    Last edited: Apr 27, 2006
  7. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Precharge pressure is the pressure in the top of the empty tank that you check with a tire gauge.

    Shut off the pump and drain all of the water out of the tank. Then check the air pressure. Is should be adjusted to 2 psi LESS than your START pressure of 40 psi. If the pressure is too low, add some air with a compressor or bicycle pump. If it is too high, let out some air.

    The maximum pressure depends on your pump, tank, relief valve, and pressure switch.

    Most submersible systems have a relief valve that is not adjustable and is set at 75 psi. Higher pressure adjustable relief valves are available at a lot more money.

    Your tank should have a label specifying the "maximum working pressure" which shoud NEVER be exceeded. The relief valve must be sized to discharge the full capacity of the pump without exceeding the maximum working pressure of the tank. Some older tanks are limited to 75 psi; I have seen new ones rated to 125 psi.

    Submersible pumps often have a pressure capability exceeding the maximum working pressure of the tank. Jet pumps rarely have that capability.

    I believe the FSG2 switch has a maximum setting of 65 psi. You can get switches that go to at least 80 psi.

    You can check your submersible pump capacity at working pressure by shutting off all water when the pump starts and check the time to fill the tank to shutoff. That procedure requires that you know the precharge pressure, the start pressure, shutoff pressure, capacity of the tank, and make a calculation. Another way is to open a faucet while the pump is running and adjust the flow to hold the pressure constant in the middle of the pumping range. Then measure the flow with a 5 gallon bucket and a watch with sweep second hand (they still make that kind).

    But the easiest way is to find the model of the pump and get the manfacturers pump characteristics. They usually have a recommended flow range, which corresponds to a head (pressure measured in feet of water column) that the pump will deliver. The total head capability of the pump, minus the depth to water in the well, minus the pressure loss in the piping, is the head (pressure) available to your tank pressure. One psi = 2.31 ft of water.

    Head is the height of a column of the pumped fluid that the pump will develop. They use head instead of pressure because head is independent of density of the fluid.
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