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Thread: Pipes Hammer when pump cuts out

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  1. #1

    Default Pipes Hammer when pump cuts out

    I just recently bought the house. House sat empty for a while before i moved in. From day one the pipes have hammered. The well is 398' pump is at 265'. Cut in pressure is at 40, cut out is 60. At least that is what i have witnessed. So far i have been told that the check valve at the pump is bad. But there is no delay of pressure build up at cut in. Next one is that i have a bad pressure tank. But tank bladder holds pressure and does not quick cycle. i have drained and checked the pressure. i checked again today but noticed that with a drained tank and valve shut to the house that the tank built up 25# of pressure. Any suggestions?

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    I don't think you can get a valid reading on the tank if the valve is closed. When the pump turns off after it cycles, the air pressure in the tank will equal the water pressure. If it is 25# higher than expected, you may have a defective water pressure gauge and that would also mean that the pressure switch is set wrong as a result.

    You could get a little pressure increase when your water heater turns on, but I don't think you'd get 25# unless the bladder was shot.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
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    Is there a check valve in the house near the tank?

    bob...

  4. #4

    Default jodan

    There is no check valve in the house. i started to put one in and then realized that the hydrant out side by the well head would only run until the water in the pipe was gone. Because if it does not drop the pressure tank the pump will not get tripped on. Does that make sense? i am debating weather or not to make an expansion tank in the pipe.

  5. #5
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    If you put one in the house, the pipe underground feeding the hydrant would be at or close to zero pressure. You couldn't get a drop from the hydrant unless the pump was running.

    Do you mean one of those inwell tanks?

    bob...

  6. #6
    Previous member sammyhydro11's Avatar
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    See the reason why you are getting water hammer is because there is only one check valve inline. The reason why there is no check valve at the tank is because the person that set up that hydrant decided that he was going to run the hydrant off the main line coming from the well. He should have ran two lines in the same trench one for the supply for your home and one running off the tank in the house back to the hydrant. I had a customer w/the same issue. I replace his pump and tank. The next day he callse me back and told me he had no water coming from his hydrant. Come to find out by putting in my check valve it cut off the water going to the hydrant. When the hydrant was turned on there was no water pressure drop to kick on the pressure switch. Needles to say i removed the check valve and everything worked.

    SAM

  7. #7
    vaplumber
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    Quote Originally Posted by jodan
    There is no check valve in the house. i started to put one in and then realized that the hydrant out side by the well head would only run until the water in the pipe was gone. Because if it does not drop the pressure tank the pump will not get tripped on. Does that make sense? i am debating weather or not to make an expansion tank in the pipe.
    Dont ever put a check valve at the tank. Weve worked on many set up this way over the years. When the valve at the submersible pump starts to get weak and close slower, the valve you put at the tank will cause water hammer. Also if the check valve on the pump is weak, it can cause hammer even if you dont have any other check valves in the system. The inspectors here will fail a system if you have a check installed any where out side of the well casing. There reason being as stated earlier. If there is a leak in a pipe between the well and the tank and you put a check valve at the tank to cover a bad pump check, when the water in the drop pipe and the buried pipe to the tank falls back to the well, you build a vacuum in the line behind that new check valve, and that can cause contamination.

  8. #8

    Default jodan

    As in my reply on the 22nd the hammer occurs only when the pump turns off. As for Ranchers questions for the pressure build up. I turned the pump off, then drained the tank by opening the cold water in a tub. That did put the guage to zero. At that point i turned the ball valve to the house supply off. Why, i do not have an answer. But when i did, the pressure guage slowly rose to 25#. That is all the higher it ever went. So at that point i opened the house back up and you could hear the air enter the pipes, and the guage did go back to zero. I then turned the house back off and the pressure on the guage rose to about 25# again. At that point i cut the 1 1/4 pvc supply line where i intended on putting the check valve. Which is above the tank in a horizontal line. By all rights the water should have been gone. There was still about a gallon in that line. It did stop running, which tells me the line probably was pitched just enough away from the tank to hold the water. Yes pressure on the guage went to zero. As we all know from there i did not put the valve in, glued my pipe back in, turned on the pump, opened most all of the faucets to purge the air that was introduced. I havn't messed with anything since. Night time and holiday water repairs in the country is something i try not to do unless absolutly needed.

    After todays posting it would appear that i need to pull the pump and change the check valve. I have access to cranes. Could i pull the well on my own with out alot of issues. The reason i ask is, out of six, only one well man has returned my call and his diagnosis was a bad pressure tank.

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