New Tank Install Now Pressure Won't Hold........

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by JBRONCFAN, Mar 17, 2011.

  1. JBRONCFAN

    JBRONCFAN New Member

    Messages:
    3
    Location:
    New Jersey
    Have well water and just had the expansion tank replaced. It developed some holes and had to be replaced but the system as a whole still worked fine.

    After the tank install, the first shower I took the water pressure dropped to zero before the pump comes on.....never happened before. The plumber who installed the tank also installed a brand new pressure gauge.

    This is what happens when someone takes a shower. Pump comes on and in about 2 minutes it hits 50 psi and stops. Then about 3 minutes or so later the psi drops down and when it hits 30 it drops heavy all the way down to zero. In the shower there practically is no water coming out at this time but then the pump comes on and back to 50 psi it goes.

    Any ideas???
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    There is too much air precharge in the bladder for what the pump's kick-in pressure is set to.

    What is happening is the tank empties completely when it should not. The air in the tank is what provides the pressure. Pumps use some of the pressure to work and when it drops to zero, it works less efficiently until the pressure returns.

    Note that you need to calibrate your air pressure gauge with your water pressure gauge. The air gauge is used to set the precharge 2 or 3 PSI below the pump's kick-in pressure and most people use the water pressure gauge to determine that, hence the need to calibrate.
  3. JBRONCFAN

    JBRONCFAN New Member

    Messages:
    3
    Location:
    New Jersey
    Thanks so much for the reply. Now what do I do to fix this??? Please don't leave any details out.
  4. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    Do you know at what water pressure the switch is set to turn on the pump? Does your air gauge read different than your water gauge? If the air gauge and the water gauge read the same, drain some water from the tank until it is close to the kick-in preset and measure the air pressure again. It should read the same as the water pressure. If it does not, try to find another air gauge that does. If different air gauges read the same but don't match the water gauge, suspect the water gauge and add the appropriate fudge-factor to the water gauge reading or buy another water gauge.

    Isolate the power to the pump and drain the tank completely. Measure the air pressure at the shraeder valve on the bladder. When the water pressure is zero, the air pressure in the bladder should be 2 or 3 PSI less than the kick-in pressure. If the air pressure is higher considering the determined fudge-factor, release air as needed.

    If the air gauge and the water gauge read the same through all the above tests, and the precharge is less than the kick-in, suspect the pressure switch. Minerals can build up under the diaphragm, preventing consistent kick-in pressure. You could raise the kick-in pressure a few pounds to buy you enough time to get to the store.

    It's a matter of repeating tests with minor adjustments as needed until the results are satisfactory.
  5. JBRONCFAN

    JBRONCFAN New Member

    Messages:
    3
    Location:
    New Jersey
    Success!!! I read the instructions on the side of the new tank, I also found an air tap like you find on a tire to pump it up. I put an air gauge on it and found it had 38 psi on it. The instructions say it should be 28 psi if you have a 30/50 system which we have. So I turned off the water pump, opened up the kitchen faucet until it stopped running. I reduced the psi down to 28 psi on the tank, turned on the water pump and then turned on the shower. Watched the pump and instead of dropping to zero at 30 psi, it kept going and at 23 psi the pump came on!!!! NEVER went all the way down to zero so I am very happy.

    It looks like the tank is made to handle a 40/60 system, the highest pressure pump cause it's much easier to go down in pressure than it is to add pressure. The plumber knew we had a 30/50 system and was too lazy to make sure the tank pressure was correct.
    Last edited: Mar 18, 2011
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    If the kick-in is at 23 PSI, the precharge on the tank should be 21 PSI but don't go there yet. Consider raising the kick-in.

    If your system was intitially a 30/50 and is now dropping all the way down to 23, you may have a build-up of minerals under the diaphragm. Is the pump still shutting off at 50? If yes, the switch is suspect. They are designed to have 20 PSI differential.

    Does your pressure switch have one spring or two? If it has one spring, raising the kick-in will raise the kick-out. If it has two springs, the big spring will raise both while the small spring affects only the kickout.
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