pump pressure dropping

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  #1  
Old 10-01-19, 04:32 AM
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pump pressure dropping

I have a jet pump and when using water for a few minutes pressure goes down to 30psi then drops fast to around 20psi and stays there til water is turned off then build back to 50psi. Its has a 30-50 switch and pump was replaced a year ago. Test tank air pressure and its at 28psi. I removed the line going to the switch and its fine too. Now we havent had much rain in 3 months so could my well be low causing this? What else should I check?
 
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  #2  
Old 10-01-19, 05:11 AM
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What type of jet pump do you have? Shallow or deep well?

Do you notice any air in the water?
 
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Old 10-01-19, 06:39 AM
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No air in water. I believe it's a deep well
 
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Old 10-01-19, 08:56 AM
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You could try removing a few psi of air and see if the problem fixes. If not, put the air back in. Even though you say you have 28 psi of air and a 30psi cut in pressure, one of those guages may be inaccurate or a little inaccuracy on both. If the air pressure is higher then the water pressure, the tank will push ALL the water out of the tank before it turns on. Since a pressure tank can only exert pressure on water that is actually in the tank, when this happens one can experience a quick drop in pressure and then the pump kicks on. Almost identical to what is happening with your system.

It may not be your problem but is easy to check.
 
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Old 10-01-19, 09:16 AM
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But how can a tank just get too much air all of a sudden. Also how co.e pressure doesnt build back up once the pump kicks on and water is flowing?
 
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Old 10-01-19, 09:48 AM
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The pressure tank does not pump water and it does not generate water pressure. You can totally screw-up the air pressure in the tank and you will still have exactly the same water pressure.

Since you have a deep well jet pump (with two pipes leading to the well). I would pull the well and clean the venturi at the bottom. A partial clog can prevent your pump from developing full pressure and can even stop it from priming.
 
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Old 10-01-19, 10:53 AM
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I won't quibble on whether a pressure tank generates pressure. Obviously the pump generates the water pressure and the tank stores it for future use, but when the pump is off the water pressure is coming from the air in the tank.

As for whether or not an air pressure above the pump cut in pressure is causing your problem; I have no idea. If it did, the symptoms would be almost identical and as I said, it would be a lot easier to check then to pull the venturi out of the well.

Pilot Dane knows a lot more about this stuff then I do so if I had to place my bet now that he has chimed in, I would bet he will probably end up being right, but as I said, my suggestion is pretty easy to test out and eliminate.
 
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Old 10-01-19, 12:13 PM
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Pilotdane, I only have one line coming g in from the well so it must be a shallow well.
 
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Old 10-01-19, 03:01 PM
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ok so I just raised the psi to 31 just to see if it changed anything and its the same. Should i lower it to 25? Ive never heard of a tank gaining pressure just lowering it.
 
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Old 10-01-19, 05:18 PM
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Did you have the well pump turned off and open a faucet to remove all water pressure both times you checked the air pressure in the pressure tank? The air pressure can only be measured when the water system has been completely depressurized. If there was any water pressure when you measured it will throw your readings off.
 
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Old 10-01-19, 05:23 PM
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yep. I used the drain at the bottom of the tank but didnt turn on any faucets if that matters
 
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Old 10-01-19, 08:33 PM
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Is this well for drinking water ? Pretty rare to see a shallow well in NJ.

When you air charge the tank.... the system water pressure needs to be 0. That you can see on the gauge.
when using water for a few minutes pressure goes down to 30psi then drops fast to around 20psi
Changing the pressure switch settings isn't going to help.
The pump should start at 30psi and should start immediately climbing. If it doesn't climb..... your well is not delivering water.
 
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Old 10-02-19, 03:48 AM
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Yes its for drinking water. Yes the gauge was at 0. Could my newer pump be going out? I dont know if I can even access my well. My line just goes into the basement floor. Its a flojet
 
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Old 10-02-19, 05:55 AM
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Yes, pumps can get weaker with time. Silt, sand and other solids in the water can erode the vanes of the pumps slowly diminishing it's efficiency over time. If your water problem has been slowly getting worse over a couple years it's a possibility but if your water problems started suddenly then that is probably not a worn out pump.
 
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Old 10-02-19, 07:44 AM
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I said to "remove" air from the tank, not add it. Adding air would just continue the problem. The air in the tank MUST be below the cut in pressure of the pump or you will get symptoms like you indicated. When the air pressure is above the cut in pressure, the higher air pressure will push out all the lower pressure water from the tank. Whatever is higher pressure will always win this pushing contest.

Remember, when the pump is off, it is this pushing effect of the compressed air that provides the water pressure to the house. You want the pump to kick on before all the water gets pushed out of the pressure tank or you can get some quick pressure drop offs before the pump actually kicks back on. This is done by ensuring the air pressure is below the cut in pressure of the pump. For this test, I would take out more then 5psi to make sure. Lower air pressure will not create a big problem for your system. Too low of air pressure just means that you get less water from your pressure tank between pump off and pump on again. Since we want as much water as we can get, but we don't want to have an improperly working system, we are told to use 2 or 3 psi below cut in pressure. For this test I would want to do more since I can never be sure of all the numbers due to measurement errors on guages, pressure switches not set exactly as stated and of course changes that might occur due to temperature changes. The air pressure in the tank will change with temperature to a larger degree then the water, etc.

How things might have changed, in your case, I have no idea. I don't even know that they did. But I would definitely test this theory before doing any other major repair or check.
 

Last edited by OptsyEagle; 10-02-19 at 09:15 AM.
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Old 10-03-19, 02:58 PM
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dropped pressure to 25psi and test. Just as bad if not worse. Only thing I can guess right now is my well is drying up.
 
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Old 10-05-19, 07:19 AM
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Well at least we got the problem being too much air in the tank ruled out. It was a fairly easy thing to check.

I don't know about your well running dry. If it was you should be seeing air shoot out of your taps and perhaps your pump losing its prime from time to time.

The only way your pressure would stay stable when you were drawing water is if the pressure lost to the water draw was being replaced by pressure from your pump. It sounds to me that your system cannot keep up with the water draw, since as you say, the pressure only goes back to 50psi when you stop using water.

I would think that either your pump is losing some of its pumping power or you have a clog somewhere. My guess there would be a clog in either the venturi inside the pump or the ejector closer to the foot valve in the well. The other option would be a clogged filter if you happen to have one in front of the pump. Not a good idea but I have seen some people install them on the intake of a pump. If you have, check that first.
 
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Old 10-05-19, 07:55 AM
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Pretty rare to see a shallow well in NJ.
Not really pete. NJ has one of the largest aquifiers in the US. Kirkwood / Cohansey

https://en.wikipedia.org/wiki/Kirkwood–Cohansey_aquifer

When I lived in Howell my whole development built in the 40's 50's had shallow wells.

My well was 30 ft deep. Single pipe. Water level was 12 ft down. I know as I found the well head 4 ft down and changed the head and foot valve. It was discovered I did not have a foot valve. What was holding the water up in the line was the check valve at the pump. Like putting your finger on the end of a straw, if you know what I mean..

going from 30 to 20 psi and maintaining seems the pump is running at capacity. Mine would do that if I ran too many GPM. These pumps are good for maybe 7 GPM with all friction looses and what not.

we need more info from op like what fixtures are being run when this occurs?

And all pumps are not created equal.. What pump do you have? You stated you replaced the pump.

I had a sears pump that lasted with no repair 20 years. I sold the house it was still working flawlwssly.


 
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Old 10-05-19, 10:32 AM
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There is a scenerio where you might have a dry well, so to speak, without getting air in the line.

A deep well jet pump can pump water down to around 75 feet, if I recall. Now that 75 feet isn't where your foot valve is. It is where the upper level of the water in your well is. For example, if you dug a well 90 feet deep and hit water at 65 feet, even if your foot valve was closer to 90 feet then 65 feet, the pump should still work. The water elevation of 25 more feet above the foot valve (set at 90 feet) would provide pumping power to your pump.

So where am I going with this. Let say when you bought your new pump the foot valve was set at 70 feet. Let's say your new pump would have had a struggle pumping from that depth, but the water was 30 feet above the foot valve, at that time, and hence the pump worked fine. Now lets say you have had a reduction in well water and the water level is only a foot or two above the foot valve. As long as the foot valve is in the water, no air will enter but your pump would have to work a lot harder then when the water level was 25 or 30 feet higher.

I hope that makes sense. Again, I can't say it is your problem but if you know a few more specs about how your well was dug and where your foot valve is set, etc., it might shed some more light on your problem.
 
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Old 10-05-19, 05:31 PM
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pump is a flotec fp4012-10. WE really only notice while showering but thats also the only time we run the water that long. Wierd thing is I just took a shower and pressure was fine for my quick shower which it hasnt been .
 
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Old 10-06-19, 12:39 PM
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That pump is for shallow wells only.

https://www.pentair.com/en/products/...mp-1-2-hp.html

Perhaps that is what you have. Do you have one pipe for incoming water or two? Info on the well would be more helpful. How deep the well is, where your foot valve is situated and what level the water is at.

It's very possible that a reduction in your water level is making your pump work beyond its abilities.
 
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Old 10-06-19, 12:40 PM
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I have one line coming into my basement. Have no other info on my well though.
 
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Old 10-06-19, 01:50 PM
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That is a shallow well pump. Deep well jet pumps have two pipes on the intake of the pump. If yours looks like the one I posted then it is definitely shallow well since that pump cannot accommodate two pipes on the intake.

Since it is a shallow well you might be able to open up the well and drop a string down there with a weight on the end and when you hear it splash, mark that point on the string. Pull it up and see how low the water level is.

Anything over 25 feet and you are going to have problems with that pump. The elevation level is to where your pump is, not where the top of the well might be.

Anyway, that is about all I got. Good luck to you. Perhaps more water is starting to flow into your well and all will be fine. If not, check what I suggested to see where you are with respect to how high you need to pump water and whether a shallow well pump will do that.
 
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