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Thread: Pump cycling with low differential

  1. #1

    Default Pump cycling with low differential

    Our pump is cycling on and off. I checked the pressure gauge and it seems to turn on around 62 and off at 66. Other posts and web searches suggest that these values should be 40 and 60. The pressure switch appears to be in two parts. One is the sensor itself connected in the pipe. A wire leads from the sensor to the electric box with relays attached to the pump.

    There is an adjustment screw the sensor part. I presume that sets the limit. But I do not see an adjustment screw for a differential.

    The pump is 25 years old. It is an above ground pump. The pressure tank was replaced in 1999 with a Champion tank.

    Is there an adjustment for the differential or did older units not have one? I presume the problem is with the pressure switch or could it be something else?

    Thanks for your help.

    Ken

  2. #2
    That's all folks! Gary Slusser's Avatar
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    Since the switch is so far out of adjustment, replace it with a 30/50 due to the age and type of pump you have. Clean any debris out of the port it attaches to or any tubing or nipple it is mounted on, along with any tubing and fitting any tubing to the switch is screwed into and the holes the fitting is screwed into.

    Adjust the air pressure in the tank to 29-28 psi with no water in the tank and see if your problems clear up. If not describe what is happening then.

    Gary
    Quality Water Associates

  3. #3

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    Thanks for the answer. I'll try it out and let you know if that doesn't fix the problem.

  4. #4

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    If there's a wire from the pressure sensor to a box with relays, it almost sounds like this is a constant pressure unit.
    Ron

  5. #5
    That's all folks! Gary Slusser's Avatar
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    Good call Ron. I have no experience with constant pressure pump systems.

    Gary
    Quality Water Associates

  6. #6

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    kp,
    Have someone check out your unit for you. It sounds like you may have a constant pressure (cp) unit, which has a very small differential, usually only a couple of psi. A cp unit will ramp the pump motor speed up and down to maintain the preset pressure. If the unit is working correctly, and the pump still cycles with no water demand, you may have a bad pressure tank. Pressure tanks on a cp unit are usually much smaller than what would normally be used.
    Ron

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