Double Check Valves .............. Again!

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by tvl, Aug 10, 2006.

  1. tvl

    tvl Member

    Jul 5, 2006
    South Carolina
    Hello All,

    A while back, I read several post discussing why it was best NOT to use two check valves. All the cons made perfect sense and I logged the information in the "back of my head".

    I am currently using two check valves and have been doing so for the past 10 years, which is how old our 1 HP submersible pump is this month (hangs 145 feet). The well is used primarily for irrigation, but is also used for all outside water needs ...... such as washing the car, washing the house down, etc. Thus the reason we use a 40 gallon captive air tank with the setup.

    One check valve is on the top of the pump itself and the other is underneath the house just before the captive air tank. I have never heard any unusual noise until today. After cutting the water off to the sprinklers, there was a very audible "thud" at about the point where I would suspect the pump cut off.

    Now, from the previous discussions, I know what caused the "thud". My question is as follows:

    I would suspect the check valve that is leaking is the one on the pump. Is this a correct assumption? I would think if this check valve was holding properly, the other valve near the pump wouldn't even come into play????

    I will remove and discard the check valve near the tank this weekend. However, if the other valve on the pump is truly leaking, will I still have the "thud" at times. I am aware the tank will empty itself if the pump check valve is leaking badly and I remove the one near the tank. I guess what I am wondering is if I remove the valve near the tank AND the valve on top of the pump is truly leaking, will I be forced to change the pump check valve also????


  2. Gary Slusser

    Gary Slusser That's all folks!

    Aug 31, 2004
    Wherever I park the motorhome.
    Yes because a leak is a leak. That will empty the tank into the well and cause the pump to run periodically. Not replacing the pump check may cause air infiltration as the water causes suction on the drop pipe and its fittings and pitless oring if you have a pitless.
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  4. speedbump

    speedbump New Member

    Jul 15, 2005
    Water well and pump tech.
    Riverview, Fl.
    Take it out and see what happens.

  5. valveman

    valveman Cary Austin Staff Member

    Mar 15, 2006
    Pump Controls Technician
    Lubbock, Texas

    Taking out the top check sometimes helps the bottom check stay closed better. If bottom check is leaking a little, pressure tank will drain back and pump will cycle on and off occasionally. If it cycles very often, pump may be spinning backwards which will break a pump shaft on start up. Also the cycling will destroy motor, control box, pressure switch, etc.. If the power goes off when bottom check or both checks are leaking back, it can implode the tank or piping. Need to get it fixed ASAP.
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