Pressure switch chatter - location or tank pressure?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by gbeens, Dec 20, 2013.

  1. gbeens

    gbeens New Member

    Hi everyone, I adjusted my pressure tank air bladder to better line up with the pressure switch, and the change introduced a lot of 'chatter' at the pump cut-in (none at cut-off though). I have a valve right near the pump's outlet that I closed about a third to fix the symptom while I take on the cause of the problem. So I read a lot of the helpful info here about the chatter being related to the pressure switch's placement, and I can certainly move it next to the tank if I have to, but the switch currently reads the pressure right from the pump's housing itself, and it seems like it came assembled that way with the switch physically attached to the pump as well. So, I thought I would check with the pros here and see if there wasn't some other cause given that the set-up seems factory (Goulds JS10 pump, some SquareD two screw switch).

    Anyhow, I noticed, after adjusting it, that the tank said it came from the factory set at 38 psi (WX252). Now my switch was cutting in at 20 and out at 40, so I brought the tank's pressure down from 21 to 18. Could the switch's problem have something to do with the fact that my tank is inflated 20 psi below it's 'design' or is that irrelevant? I would rather just adjust the pump switch to a 40-60 psi range if that is what the tank is set up for and see if the switch behaves itself than re-plumb its location in the line. Do I risk damaging some fittings/fixtures at that pressure? Let me also say that nothing the previous owner did in terms of electrical or carpentry instills any confidence in his plumbing skills.

    Any thoughts? Thanks in advance.
  2. Reach4

    Reach4 Well-Known Member

  3. LLigetfa

    LLigetfa DIYer, not in the trades

    NW Ontario, Canada
    Why would you have the pump come on at 20 PSI? I would never tolerate such lousy pressure. You say nothing about your well but if the pump can do 40-60, then that's where I would set it.

    If you have a tank Tee with a port for the sense line, I would move the sense line. Closer to the tank is always better. It's just convenient for the pump maker to have a fully plumbed up product which is why they plumb the sense line to the pump body.

    Also, I think you may be shaving it too close being just 2 PSI below cut-in. First off, your air gauge may not read the same as your water gauge. Jet pumps use pressure to make volume and more pressure. If you shave it too close, the pressure can take a dive on start under heavy draw. I would be more comfortable with 5 PSI spread.
  4. DonL

    DonL Jack of all trades Master of one

    Houston, TX
    Sounds like someone may have been tweaking the pressure switch differential setting, instead of the cutoff pressure adjustment.

    Did you drain your tank when you adjusted the air pressure ?

    If it was switch location, then closing the input to the tank would make things worse, not better like you say it is doing.

    Good Luck.
  5. Boycedrilling

    Boycedrilling In the Trades

    Royal City, WA
    The pressure tank does not have a "design" pressure. It is precharged at the factory, but the pressure needs to be adjusted when it is installed. The precharge needs to be 2 to 4 psi LESS than the cut-in or low pressure setting of the pressure switch.

    You have a jet pump that has the pressure switch mounted directly to the pump motor. It then has a plastic psi sensing tube from the pressure switch to the pump housing. You don't mention how far away from the pump the pressure tank is. If you throttle the valve between the pump housing with the pressure sensing tube and the pressure tank you ARE making things worse, not better.

    You could plug the port on the pump housing and run the sensing tube to the plumbing at the pressure tank. The purpose of the pressure tank is to absorb those pressure spikes and also to provide water storage to cycle the pump.

    There is one possible solution, that probably doesn't apply to your exact situation, but might help someone else. Square D does make a pulsation damper that can be placed in the pipe fitting of the pressure switch. It looks like a "sombrero" with the tip of the hat cut off. They cost a dollar or two, and can sole a chattering problem in SOME situations.
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    NW Ontario, Canada
    What you say makes sense. There has to be some other factor at play here. I'm wondering if there isn't a low pressure cut-off on the switch and the pressure is dropping as the jet pump steals some of the flow to service the venturi jet.

    I think it's a case of having to be there to properly diagnose the issue.
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