Shallow well pump, broken foot valve?

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Old 09-11-19, 08:32 AM
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Shallow well pump, broken foot valve?

Ok guys, new problem. So Iíve been combing though the forum before posting to see if I could find my answer.




Situation: I have a 3/4 shallow well jet pump that I use for lawn irrigation (see picture) that for the last year or so has intermittently cycled even without any lawn valves open. I just thought it was a slow leak somewhere between my pump and irrigation valves. The last 3 weeks Ive had the problem where my pump has run dry. Its not that the well has run dry because once I prime it and it pulls a vacuum, after a minute or so itíll bring back water (clear) and I can run it for hours with no problem. On one occasion, I didnít catch it and it burned up my impeller.




I just installed a vacuum gauge on my suction side. When I first turn the pump on, the gauge will read around 7mg Hg and then after about a minute it will start to increase until about 23 mg of Hg and the water starts to flow. If I shut the pump off to see if the vacuum holds, it will start at 7mg of Hg and then slowly over 5/10 minites decrease in vacuum. Iím assuming thats the water going back down the well. Interestingly, it will only pull water if I have an irrigation valve open. It seems that if there isnít a sufficient ďloadĒ of water being drawn from the well through an open irrigation valve, the pump will continue to run and never really pull a strong enough vacuum to pull water up the well. I think that it when my impeller burned up.




What I think is happening is my foot valve in the bottom of the well has failed and the water is slowly going back down the well. So every time the pump starts, it has to pull that column of water up 25í. You might be able to see in the picture, I have a check valve right at the end of the suction line before it goes into the pump. I donít think that is the part thatís failing. It wouldnít have anything to do with water going back down into the well. I also donít think I have a leak anywhere in my lines before the well. Ive replaced most of the 3/4Ē line by now. Is there a way to double check that I have a vacuum leak in the lines?




I donít know how the foot valve could have gone so quick, I ďjustĒ had this replaced about 5 years ago. A pump guy came and put a whole new pipe with the point in. I just want to make sure its the foot valve. I donít think its that hard to pull the pipe up and replace the point, just seems time consuming. So I want to make absolutely sure that its that before I go ahead with the project.




On a side note, because I live in MassachusettsÖ In the winter when I blow all the lines out Ö if my foot valve is working properly doesnít that water just sit in my vacuum line and all the way down the well, waiting to freeze and crack my pipe? Is it possible that I donít even have a foot valve down there (because of that logic)? Thanks in advance for the help.

 
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Old 09-11-19, 09:04 AM
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Yes, if your foot valve does not leak all the water above it will remain in the pipe.

I'm too lazy to read the whole story. Did you have another question?
 
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Old 09-11-19, 10:15 AM
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My really big concern is that the pump is taking a really long time to draw water from the well. I may not even have a foot valve. Is this correct? I have heard that shallow wells a lot of times donít need a foot valve. So the only day off I might have is the check valve at the pump. Do all the symptoms mean that itís just a bad check valve?
 
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Old 09-11-19, 11:47 AM
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If the pump is self priming a foot valve is not needed though it will help you get water sooner by preventing the pump from loosing prime. Most well pumps are not self priming and do require a foot valve.

The reason you can't get your pump to prime without turning a irrigation zone on is there is nowhere for anything to go. Priming is a very weak function relying on earth's air pressure. If you don't have any zones "open" then the air on the output side of the pump has nowhere to go. The air pressurizes and the pump can't suck water uphill against the air pressure in the system. The outlet side of the pump must "burp" or breath to let the air out for priming. Once the pump is primed then it can tolerate resistance on the output side.
 
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Old 09-11-19, 12:00 PM
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I actually just figured it out. I did a "shaving cream" test and found a leak between well and pump. It was such a pinhole, I can't believe that was the problem and getting with the vacuum. I plugged it and not it stays at 7" of Hg. Looks like thats all it was. Thanks for all the help
 
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Old 09-11-19, 12:03 PM
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that also make a lot of sense about priming if a irrigation zone isn't open. I'm learning more than I ever knew about wells through this experience. Thanks
 
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Old 09-11-19, 03:45 PM
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A pinhole is all it takes. It will draw air in and no water will leak out making it tough to find.

Since you are intending to drain the well lines..... you cannot have a foot valve.
You have a check valve right at the pump. Technically that services the same function as a foot valve.
 
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