Low water pressure

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I am so confused. I had good pressure on my water well. It has a submersible 1/2 HP pump and a pressure tank. I replaced the check valve and everything was fine. But the pressure gauge was cracked and not working correctly so I replaced it a couple days ago. Now the well won't pump up past 20 pounds. it was getting up to 40, now only 20 with main shut off. How do I add air pressure and how much pressure should I have? Plus I think I have other problems as well, but I have to start somewhere.
 

LLigetfa

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I replaced the check valve and everything was fine.
What check valve did you replace and why? Also, what is the pressure switch set to? Assuming a captive air tank, what precharge pressure is it set to?

With a captive air tank, the only check valve there should be between the pump and the pressure tank is at the pump. If it was a top side check valve, it might have been responsible for water hammer that can destroy not only the check valve and pressure gauge but also the piping between the pump and the tank. Chances are that water hammer created a leak in the pipe which in turn prevents the pump from reaching cut-off pressure.

A properly sized submersible should be able to produce more than 60 PSI and some more than 100 PSI. To know if it was sized properly, we would need to know more about the well static and draw-down water levels.
 

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The old check valve has been leaking for over a year. It was a slow leak , but it bothered me and I finally had time to replace it. the check valve is between the pump and the tank. I'm not sure what you mean by precharge pressure. I had it set to shut on at 25 and off at 50 I am just south of San Antonio Tx in Bexar county.
 

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Check valve had a slow leak so I replaced it. It is a top side check valve, but the old one has been on there for at least 50 years. It is between the tank and where the pipe goes down to the pump. I don't know what the well static and draw-down water levels are. Before I started having trouble I had it set to go on at 25 and off at 50.
 

LLigetfa

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I'm not sure what you mean by precharge pressure.
A captive air tank is one that has a bladder or diaphragm separating the air from the water as opposed to a hydro-pneumatic (HP) tank that has no separation between the air and the water. Captive air tanks are precharged with with air about 2 PSI less than the pressure switch cut-in setting, so 23 PSI in your case.

HP tanks are not precharged but rather have air added every time the pump turns on. This is normally done by having a bleeder valve in the well that opens to drain water out while a snifter valve on a top side check valve lets in air. A HP tank has an Air Volume Control (AVC) that removes excess air.

The above describes the theory of operation. When it does not operate as it should, due to a failed bleeder or snifter, the check valve creates water hammer that can damage the pipe and the check valve. When the air in the HP tank gets absorbed into the water (waterlogged) the pump will short cycle which will destroy the pump, the switch, and generate more water hammer.
 

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According to what you said, I have an HP tank. I am fairly certain there is no bladder because there is seepage along a seam in the metal pressure tank. The old check valve had a valve stem or Snifter valve. But the new check valve did not come with a snifter valve and I could get the old one out. So I installed the check valve without a snifter. It worked fine for the last two weeks or so, then on Thursday it would build up as much pressure as it used to. It sounds like I just need to get a new snifter valve. Correct? Where would the AVC be? Is that something I need to worry about? Thanks for all your great help.
 

LLigetfa

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The AVC would be on the side of the tank. It might have a float attached to it or it might use a diaphragm to sense the level of the water in the tank. A failed AVC of the type that works to remove excess air does not usually cause the tank to waterlog. The other style of AVC that adds air rather than remove air, can cause a tank to waterlog.

A shortage of air in the HP tank, while a bad thing, will not directly cause the pump to not be able to build enough pressure to shut off but it would cause the pump to short cycle. A short cycle is when the pump reaches the shut-off pressure but the pressure quickly drops with a small amount of water use. If your pump cannot reach shut-off pressure, the fault lies elsewhere.

Do note that a snifter valve has a weaker spring than most tire valves. There might not be enough suction created by the bleeder for a stronger spring to open to let in air.
 

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We are still GUESSING what type tank you have. Post a picture so we can tell what you have. But either way the tank, AVC, snifter, none of that has anything to do with your pump not building enough pressure. Because it happened fairly rapidly, I believe you have a hole in the drop pipe and not enough water can get to the top of the well to make any pressure.
 

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I am fairly certain there is no bladder because there is seepage along a seam in the metal pressure tank.
There should be no leakage along any seams. As the water level within tank will be lowest just before the pump is to be activated, depending on the location of the defective seam, air is likely to be leaking out whenever the water level is lowest.

It would seem that your pressure tank should rightly be replaced.
 

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The seepage is very slight, but it is there. This is why I think I have a tank without a bladder. But I can't remember what I purchased roughly 20 years ago. It's a metal tank about 6' tall and 2' in diameter. My pump is a 1/2 HP submersible type. I replaced it also maybe 30 years ago. I will post a picture as soon as possible. As far as I can determine from everyone's responses is that it is best to replace my tank even though the seepage is slight. It's a shallow well, about 70' deep, but I don't have anyone to help me pull it so I will have to get a water well company to come out and pull it. This is why I'm a little hesitant. I don't want to spend the money to pull the well is I don't have to. Since I know the tank is seeping enough to get the floor wet, I suppose I should replace that first and then see how it acts. Do you agree? Thanks for everyone's help.
 

LLigetfa

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A bad tank would not be responsible for the pressure not getting above 20 PSI unless it had a huge hole in it and the water gushed out faster than the pump can replace it. Either the pump is bad or there is a leak between the pump and the tank.

If you plan to replace the HP tank with a captive air tank, you will have to remove the bleeder that is most likely down in the well which will require that the pump be raised.
 

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I appreciate your advice and wisdom. I have a feeling, after talking with you, there is a leak in the down pipe somewhere. Got a crew coming out to pull the pump tomorrow. Then I'll make the decision to go ahead and and replace the tank at this time or let it seep. If I replace it , I would rather go back with the same kind of tank, an HP. Thanks to all for helping me out.
 

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What check valve did you replace and why? Also, what is the pressure switch set to? Assuming a captive air tank, what precharge pressure is it set to?

With a captive air tank, the only check valve there should be between the pump and the pressure tank is at the pump. If it was a top side check valve, it might have been responsible for water hammer that can destroy not only the check valve and pressure gauge but also the piping between the pump and the tank. Chances are that water hammer created a leak in the pipe which in turn prevents the pump from reaching cut-off pressure.

A properly sized submersible should be able to produce more than 60 PSI and some more than 100 PSI. To know if it was sized properly, we would need to know more about the well static and draw-down water levels.
As stated in previous posts, my HP pressure tank is seeping in 4 or 5 places. It is slight seepage, but enough to keep the floor wet under the tank. Should my tank be replaced while we are doing all this other work?
 

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If the tank is leaking it certainly needs to be replaced. But it is unusual for a tank to fail from the outside. Normally tank bladders/diaphragms fail because the pump is cycling on and off too much. Cycling also causes the failure of check valves, pressure switches, control boxes, and other things. If your going to replace the tank might as well upgrade to a Cycle Stop Valve system that only needs a little 4.5 gallon size pressure tank, will make your pump system last longer, and deliver strong constant pressure to the house and showers.

 

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If the tank is leaking it certainly needs to be replaced. But it is unusual for a tank to fail from the outside. Normally tank bladders/diaphragms fail because the pump is cycling on and off too much. Cycling also causes the failure of check valves, pressure switches, control boxes, and other things. If your going to replace the tank might as well upgrade to a Cycle Stop Valve system that only needs a little 4.5 gallon size pressure tank, will make your pump system last longer, and deliver strong constant pressure to the house and showers.

Roughly what is the difference in price between the upgrade and replacing the HP tank with another one like it? It is probably about a 60 gallon galvanized HP tank. Thanks for your advice.
 

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The PK1A complete kit is like 525 bucks these days. Let us know what a galv tank cost please. Got to get rid of the bleeder to switch to a diaphragm type tank.
 
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