How can a New Jet Pump Cause Pressure Switch Problems?

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by mnocket, Apr 27, 2018.

  1. mnocket

    mnocket New Member

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    Apr 27, 2018
    Location:
    Colorado
    I'll TRY to keep this short... I had a new pressure tank installed because the bladder broke. Everything worked fine. Several weeks later I decided to replace the jet pump because the service tech said my pump was 25 years old. That's when the problems started. They installed a new jet pump and pressure switch. I lost water 3 times in next week and each time although the points in the switch appeared closed, I found that the pump would start if I pushed on the points.

    I called the installer and they came and replaced the pressure switch.
    Same problem persisted.
    They once again replaced the pressure switch.
    Same problem persisted
    They replaced the pressure switch.
    Same problem persists

    It's pretty clear that the problem isn't the pressure switch. By process of elimination it must be the new jet pump causing the problem. I can't understand how a pump can cause the pressure switch to fail to close. I do notice that when the pressure switch comes on, the points don't close smoothly. They kind of do a "double bump".

    Any idea how a pump can interfere with the operation of the pressure switch. The installer is understandably reluctant to replace the jet pump since when it gets power it works fine. It seems to be some sort of start up issue.
     
  2. LLigetfa

    LLigetfa DIYer, not in the trades

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    Maybe the pressure switches are poor quality? Where is it installed in relation to the tank and pump? If installed on a nipple, has the nipple been cleaned or replaced? Is there a sediment problem? I've seen where sediment/minerals build up under the switch diaphragm that prevents good contact closing.

    A bouncing switch is often the result of it being too far from the tank. Consumer grade pumps most often come with the pressure switch mounted on the pump which is not ideal.
     
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  4. valveman

    valveman Cary Austin Staff Member

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    The pressure switch being too far from the tank or too much air in the tank will cause a switch to bounce. But it will not keep the switch from closing when the pressure is low, so you shouldn't have to manually push the points together. What brand of switch is it?
     
  5. mnocket

    mnocket New Member

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    Colorado
    Yes the pressure switch is installed on the pump. There is a small tube that runs from the switch to the pump housing. When the tube is disconnected during switch replacement water runs freely from the tube as residual water drains. I can't rule out sediment build up on the diaphragm as I haven't looked for it, but it seems unlikely that enough sediment could build up in such a short time (1 week).

    Another question..... Is the operation of the pressure switch purely mechanical? Diaphragm moves due to pressure change - pushing points to closed position..... or does the diaphragm movement engage an electromagnet that pushes the points closed?
     
  6. Reach4

    Reach4 Well-Known Member

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    I agree with the previous replies.
    Measure the voltage across the terminals that go to the switch contacts. The left two terminals are across the left switch contact, and the right two are across the right contact. When the switch looks closed, each contact should have about zero volts across it. The two wires to the pump should have line voltage across them.

    If you don't have a suitable multimeter, it's time. If you can get one that includes a clamp-around ammeter, that will also be useful for future diagnosis. Plus you can take baseline current readings to record for later comparison.

    You did not say whether you are running with 120V or 240V. If running 120, some people wire the contacts in parallel.

    Some times there are really coincidences. Another possibility would be that the

    Mechanical
     
  7. mnocket

    mnocket New Member

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    Colorado
    Here's a pic of the pressure switch. When the points appear closed but the pump doesn't start, the voltage across the yellow connectors (line in) is 120v and across the white wires (out to pump) 0v. It seems that the points are not really closed - in fact if I push on them lightly the pump starts. So the points don't close and it's just so hard to believe that 3 pressure switches all have the same problem. I have noticed that my 5 micron filter which is downstream from the pump is getting dirty very quickly and has some large (visible) particles collecting. This is new and I'm told it's a result of lack of precipitation. I'm in the Colorado foothills and our wells are fractured-rock aquifer. No problem with water supply, but I'm told during dry periods silt can build up.

    It seems that the next step is to add a filter (50 micron?) before the pump to prevent sediment getting into the switch and impacting the diaphragm. I'm guessing that adding a filter before the pump is uncommon, but it seems I need to. I've got a large 500gal storage tank that feeds the jet pump. It seems the best immediate solution is to add a filter right before the pump to catch any sediment coming from the storage tank. However in the long run it would seem that it would be best to add the filter before the well water enters the tank to prevent sediment build up in the tank itself. Any thoughts on where best to add the filter?
     

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    Last edited: Apr 27, 2018
  8. mnocket

    mnocket New Member

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    I've posted some pictures in reply to Reach4 that show the installation. The pressure switch is mounted on the pump with a small hose running to the pump housing as seen in the pics. The pump itself is very close to the pressure tank (less than 2ft). It seems the consensus is that I've got sediment build up interfering with the operation of the switch diaphragm. I have noticed that my downstream 5 micron filter is getting dirty very quickly and it trapping some large (visible) particles. Looks like I should add a filter before the pump or before the well water enters the 500 gal storage tank. Any advice on adding the filter - 50 micron? before or after the storage tank? Before would keep sediment from building up in the tank, but any sediment already in the tank would still be a problem.
     
  9. Reach4

    Reach4 Well-Known Member

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    Location:
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    Your pump is running on 240 ("230").

    Ideally the pressure switch would have been mounted "closer" to the pressure tank. The symptom not having a close enough connection would be to turn off early or some such. Your symptom about starting the pump by pushing the contacts is not caused by that however.

    If you had not already replaced the pressure switch a few times, then we would expect a bad pressure switch. So now, get the multimeter. Numbering the switch terminals 1, 2 , 3 , 4, then the voltage between 1 and 4 will be about 240 volts plus or minus maybe 10%. That should be about the same whether the pump is running or not.

    When the switch is closed (on) the voltage 1 to 2 should be less than a volt. Same for 3 to 4. If this is found not to be the case, you have a third bad pressure switch.

    Also, you want to read up on setting and checking the air precharge.
     
  10. mnocket

    mnocket New Member

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    The pump is dual voltage running at 120V. I had the installer verify that the pump was set to 120V (he said there was a thing you turn inside the rear housing of the pump). I took the voltage measurements - about 1/3V terminals 1-2 & 3-4, 120V 1-4 & 2-3.

    I understand that the pressure tank setting should be 2-3psi below the switch cut-in pressure. I take it I should just drain the pressure tank and then take the measurement?
     
  11. Reach4

    Reach4 Well-Known Member

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    For a jet pump, it would be more like 3 or 4. The symptom of having the precharge high would be a stutter in the pressure as the pump cuts on. It is not harmful beyond that. If the air is too low, it is harder on the pressure tank.

    Yes. The air and pressures will be about the same when the water pressure in the operating range. That can be useful to compare the calibrations on your air and water pressure gauges.

    But yes. The precharge is set when the water pressure is zero which also means the pressure tank is empty of water.

    Your pump is wired for 120? Usually, when you are running 120, you don't switch the neutral. It would be OK. So anyway, check the voltages.
     
    Last edited: Apr 27, 2018
  12. mnocket

    mnocket New Member

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    The tank pressure is 38psi and the pump cuts in at 42psi so looks like it's right on target. The voltages are also per spec (see my previous post). Looks like most likely suspect it sediment messing with the switch. I'm going to install a filter in front of the pump.
     
  13. Reach4

    Reach4 Well-Known Member

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    NO!

    Get a voltmeter.

    If you think you are not up to it, you have some friends with voltmeters, and one will be glad to operate it for you.
     
  14. mnocket

    mnocket New Member

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    Huh? You said the reading 1-2 and 3-4 should be less than a volt. I said they were about 1/3 volt. Isn't this exactly what you said? I appreciate your help, but I'm confused.
     
  15. Reach4

    Reach4 Well-Known Member

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    Sorry. I somehow missed that.

    Repeat the voltage measurements at a time when the pump should be running, but it is not.

    You don't put a cartridge filter on the input of a pump, because it can clog. Maybe some kind of screen. But I really doubt that the problem is debris.

    The symptom you reported was that the contacts looked closed, but the pump did not run. So the problem could be that the 120 volts into the switch goes away for a while, or that one of the contacts does not make good contact at times. So the problem could be with the switch, and it could be wiring to or from the switch. You could have wiggled the wires when poking the switch, and made the intermittent go away for a while.
     
  16. valveman

    valveman Cary Austin Staff Member

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    A double bump on pump start is because there is too much distance and too many small elbows between the pressure switch sensing line and the pressure tank. If you plug the sensing line in where the pressure gauge is installed it will take out the double bump. Or you can install an additional pressure tank directly on top of that tee on then pump where the top plug is. Either way will get the sensing line closer to a tank.

    Now when there is no pressure in the lines the pressure switch points should be closed. You should not have to push the points closed. But when a switch double bumps on pump start, sometimes it trips the overload in the motor. This overload will cool down in a minute or two and the pump will just come back on. I am wondering if it is a coincidence that when you close the points it is just that the overload has had time to cool and that is really what turns the pump back on?

    That is a Square D switch. And while they can give problems I doubt you would see 3 bad ones in a row. You can't filter the suction side of a pump as that would create too much restriction for the pump to work properly. See NPSH for an explanation.

    I would just install a new switch where the pressure gauge is attached and not use the switch on the pump.
     
  17. LLigetfa

    LLigetfa DIYer, not in the trades

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    NW Ontario, Canada
    Agree. While sediment under the diaphragm can prevent the contacts from closing, I doubt that is the case here given the long skinny sense line. It is possible the sense line itself gets plugged with sediment. Best arrangement is to have the pressure switch on a larger nipple closer to the tank where the pressure gauge is.

    It looks like you are drawing water from a non-pressurized storage tank. If sediment is showing up in your filter then you should be cleaning out the bottom of that tank.
     
  18. mnocket

    mnocket New Member

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    Colorado
    I've uploaded a picture that shows the proximity of the pump to the pressure tank. As you can see, the pump is right in front of the pressure tank, although there are three 90 degree elbows from the pump to the pressure tank. I'll talk to the installer about moving the switch to the T in front of the tank. I had no idea that the pressure switch was so sensitive to location. Now that I think about it, the jet pump that I replaced also had the pressure switch on the pump fed by a small hose.......but it was connected to the pressure tank via a hose whereas the new pump is connected via plastic pipe with the three elbows. May very well be the problem. Thanks.
     

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  19. mnocket

    mnocket New Member

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    The pump is right in front of the pressure tank, although there are three 90 degree elbows from the pump to the pressure tank. I'll talk to the installer about moving the switch to the T in front of the tank. I had no idea that the pressure switch was so sensitive to location. Now that I think about it, the jet pump that I replaced also had the pressure switch on the pump fed by a small hose.......but it was connected to the pressure tank via a hose whereas the new pump is connected via plastic pipe with the three elbows. May very well be the problem. Thanks.
    I understand the issue with installing a filter on the suction side of the pump. What do you think about installing a filter on the line that feeds the storage tank (from the well pump)?
     

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    Last edited: Apr 28, 2018
  20. valveman

    valveman Cary Austin Staff Member

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    Yes filter the water as it enters the storage tank. And yes a stronger pump and a few elbows between the switch and tank will cause a bounce.
     
  21. Reach4

    Reach4 Well-Known Member

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    The symptoms related to bounce will be solved by moving the switch. But if you are concerned about sediment to the switch (and I don't think that was your problem), you could mount that switch atop a taller vertical 1/2 inch nipple instead of a 1/4 inch nipple. I don't think that will be needed, but it is a way to deal with real sediment problems.

    Do you have a way to clean sediment from the storage tank? Maybe you could have your pressure pump pickup off of the bottom some.

    I would worry about putting a cartridge filter on the water coming into the storage tank, but if you do that, at least have a pressure bypass that will keep the well pump from burning up if the cartridge clogs.
     
    Last edited: Apr 30, 2018
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