Bad pressure switch?

Discussion in 'Irrigation' started by bblawncare, Mar 4, 2008.

  1. bblawncare

    bblawncare LawnSite Member
    Posts: 129

    My customers pump used to operate 40/60 with pressure tank. I replaced the old pressure gauge as it was leaking. Well, the leak is fixed but now the pressure switch seems to be amiss. When I first turned it on, the pump came on and pressure built to 45 then when i turned off the controller, I watched the sprinklers gradually shut down and then go off. I waited for the pressure to build on the gauge and for the pump to shut off, but the pressure continued steady @ 45 and the pump continued to run-even tho no sprinklers were operating. I shut the pump off at the electrical panel and waited for a few minutes then tried everything again. I turned zone 1 on @ the controller, pump came on @ 42psi-everything worked fine-ran thru all the zones and then turned controller off. The sprinklers were off for maybe 10 seconds, but the pressure gauge still stayed steady @ 42psi and then the pump shut down. I turned system on one more time, but this time, with zone 1 running, I completely closed the gate valve to the sprinkler system. I could hear the pressure build up, the pressure gauge barely moved off 42psi and then the pump shut off. Any ideas about what happened to the 40/60 setting? I did not touch the pressure switch during my repair. Do I babble too much?:)
     
  2. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Posts: 2,217

    I'd replace the whole pressure switch. It could be burnt points, weak springs, or something else. I guess you have checked the tank pressure (top) bladder. It should be 1-2 lb more than the cut-in pressure.
    Those switches used to be about $25 at Lowes.
    Open Zone One manually. Pump should come on at the lower 40lbs or so and climb and sprinklers run. It should not go up and cut off at the 60 lbs or so and cut off with the sprinklers running.
    I'm assuming it is a shallow well system. Do you have a pump-start swiitch? If so, and if your client has a well, then that could be a problem. Pump-start switches are not used when pressure switches are used.
    Go into it a little more.
     
  3. bblawncare

    bblawncare LawnSite Member
    Posts: 129

    This system runs out of a lake/pond so there is no pump start relay-only the pressure switch. And no, I did not check the pressure @ the tank and that would be because I do not know how.
     
  4. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,076

    I like on demand.
     
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,035

    Check that the passageways for pressure switch and gauge are clear. A gummed up pressure switch line will cause problems.
     
  6. bblawncare

    bblawncare LawnSite Member
    Posts: 129

    When I changed out the old pressure gauge I used a wire brush to help clean out the old tape inside. I used my finger to create a vacuum to try and get all the gunk out, but maybe I did not do quite good enough. I will check that out.

    Thanks for the input everyone.
     
  7. bblawncare

    bblawncare LawnSite Member
    Posts: 129

    I do too, but it just so happens that the Comcast cable was out on this property today....:laugh::laugh::laugh:
     
  8. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,076

    This is how to clean them. Notice bent legs, proper arm posture.

    DSCN0499.jpg
     
  9. The pressure in the tank needs to be 2psi less than kick on or the pressure tank could be bad...Did you change the 1/4" nipple going into the pressure switch?....I stated all this on your original post weeks ago...
     
  10. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Posts: 2,217

    There's a air valve on the top of the holding tank. Remove the cap and use a tire guage. If your cut-in pressure is 45PSIG then the bladder pressure should read about 43PSIG or so. I've dealt this type of system for 40 or more years. I've found that most problems are in the pressure switch. There's points, springs, moving parts. All at the mercy of wear.
     

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