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Thread: The check valve discussion.

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  1. #1
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    Default The check valve discussion.

    Shack,

    So they recommend putting it up 20 to 40 feet. That's weird. It would seem to me if you install a check valve above a pump 20, 40 feet, the pump shuts off, a vacuum is created by the water falling down to the water level or as far as it can. Then on comes the power and wham, the water column takes off at the speed of sound smacks the poppet and bang goes the water hammer. I'm not sure just how many of those whams the check valve poppet can take.

    bob...

  2. #2
    DIY Senior Member rshackleford's Avatar
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    Thatís not exactly what will happen though. I though that for a while, too. If the water level is above the check valve the hydrostatic pressure will keep the water from exiting the last two joints of pipe. The other common the pump supplier made was that they also recommend the check valve be placed at the SWL. I think this is less advisable. A small change in static water level would cause the effect you spoke of.

    Now that I think about it, I believe that Crown Pump (now Sulzer) has also recommended placing the check valve one to two joints above the pump.

    Normally this placement is a real pain the butt, especially since we are using certalok drop pipe a lot. However, I believe there are now checks that will replace a certalok coupler. It still isnít as simple as thread the mpt x fpt check right into the discharge.

    Moderator: Can we move the other pertinent discussion to this thread?
    rshackleford

  3. #3

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    Speedbump,

    I have a question on your comment that a check valve by the bladder tank was not correct. I just moved into a house that has a xtrol pressure tank and just upstream from it before the plastic supply pipe enters the house - a flomatic check valve.

    I wondered about it because I know that the well pump is more than 100 ft down, so as you mentioned in your comment on this thread the check valve just creates a huge area of vacuum as the water level drops to the pump. But if I understand you and Shack correctly, submersible pumps are installed with a check valve directly above them.

    So, it this check valve needed. I understand that houses hooked up to municipal water need a check valve inside the house to prevent contamination if siphoning occurs. Should I take this one out?

    Thanks for your comments.

    DM

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    DIY Senior Member rshackleford's Avatar
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    Itís not a check valve on municipal systems. Itís a back flow preventer! LOL
    rshackleford

  5. #5

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    OK, so I'm not on town water, so do I need this backflow-preventing check valve? It does alert me that the pump is running by rattling nicely, but speedbump said "Having a check valve at a bladder tank is a no no anyway." I'm wondering why?

    DM

  6. #6
    Plumber Cass's Avatar
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    Quote Originally Posted by rshackleford
    Itís not a check valve on municipal systems. Itís a back flow preventer! LOL
    In the Cincinnati/ Dayton area we use a Watts #7 double check valve on residences not a back flow preventer on municiple systems. Back flow preventers are required on Comercial/Industrial buildings. I have never seen a backflow preventer in a residential application.

  7. #7
    DIY Senior Member rshackleford's Avatar
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    Sorry, it was a joke.

    Anyway we should get back to the check valve/bladder tank discussion. I could be wrong but I think that he meant on the tank inlet. One way the check would never let any water out of the tank and the other way it would never let any water in. Either way it would defeat the purpose of the tank.

    If you have a check in the main service between the pump and the tank tee, I donít know that it would be all bad or entirely good either. The problem would be that you would not be able to have a hydrant or anything like that between the well and the check valve. When the hydrant was opened the pressure would not drop at the pressure switch and the pump would not receive an on command. You hydrant would not get any water.

    I donít know if these are the correct answers, but they are my thoughts.
    ld get back to the check vavle/bladder tank discussion.
    rshackleford

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