Pressure Switch Replacement

Discussion in 'Pumps and Tanks Well Forum & Blog' started by wfhsdemons, Feb 11, 2007.

  1. wfhsdemons

    wfhsdemons New Member

    Hi Everyone, I just found this forum so I figured I would ask a few questions. I had a plumber come out the other day and wanted to charge me 250.00 to replace a pressure switch. I told him thanks but no thanks I will figure it out. I couldnt believe what he wanted to charge for other things that I could of had done. If you want to know ask!!!!!

    Problem: Water just stopped in the middle of a shower the other day and then would come back on. The same thing happened today, No water when I tried to Flush.

    My assumption is Pressure switch. When I hold the contacts together the pressure will build in the tank and hold until water is used. The pressure switch isnt kicking back in when the pressure drops off again. ( sometimes it does sometimes it doesnt ) I have used sandpaper on the contacts as well

    I currently have a 20/40 switch, 1/2 hp GE motor, 7 gallon water ace tank, 1 inch PVC piping and roughly 3.53 GPM

    I am going to replace the pressure switch and go to a 40//60 for increased water pressure in the house because it is somewhat weak.

    I was told to drain the tank and increase the pressure to 38 PSI and to go from there

    I am not sure how to drain the tank of water.( I havent really looked into it yet )

    Does all this sound ok? Thanks in advance
  2. Gary Slusser

    Gary Slusser That's all folks!

    It sounds as if the switch isn't seeing the decrease in pressure.

    It and/or the nipple it is installed on and/or any 1/4" tubing and its fittings plus the holes those fittings screw into can be blocked.
  3. wfhsdemons

    wfhsdemons New Member

    Sound like a good idea to replace the nipple and line as well

    I am trying to check the pressure with a tire gauge but it only goes up to 20 lbs???

    I was told to set the tank at 38 PSI for a 40/60 switch
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    The static pressure of the tank when it is empty of water should be 1-2# less than the turn on point of the pressure switch, so 38# is fine.
  5. Gary Slusser

    Gary Slusser That's all folks!

    I'd check to make sure there is water flowing at/into the switch and if not clean whatever until it does; rather than replacing them, especially the switch 1/4" tubing and its two fittings. The 1/4" tubing is only on jet pumps, jet pumps are on the surface and submersible pumps are in the well.
  6. wfhsdemons

    wfhsdemons New Member

    Things I have done

    Connected a 40/60 Pressure Switch
    Raised the Pressure in the tank to between 35 and 38 PSI
    Replace the 1/4" hose from the pump to the bottom of the pressure switch.\
    I did not replace the nipples connected to the hose.

    When the pump was first plugged back in the pump was cutting on and off rapidly ( about every second or so )

    Turn the nut on the single spring on the pressure switch and plugged back in.

    After a couple of 1/4 turns it was fine.

    Last had the same Scenario.

    The pump was coming on and off rapidly when the water was in use after a while.

    I did another say 1/2 turn on the pump and it seemed ok.

    I think the PSI kicks in at 40 but cuts out at 50 PSI. What should I do?
  7. Bob NH

    Bob NH In the Trades

    New Hampshire
    Your 7 gallon tank is too small for a 3.5 GPM pump. Your drawdown will be only 1.87 gallons for a 40 to 60 pressure switch range, under the best of conditions, so the pump run time will be just over 30 seconds when you are not using water. If you run a 20/40 pressure switch setting, you can use a tank with an actual volume about 3 times the GPM of the pump. If you are going to run a 40/60 range, then the tank should be about 4 times the GPM of the pump.

    I assume that you have a bladder tank.

    You may have a tank that is leaking air. Measure the air pressure with a tire gauge when the pump is off and there is water in the tank. It should be the same as the water pressure gauge. If not, one of the gauges is wrong or there is no air in the tank.

    Drain the tank again by shutting off the pump and opening a faucet until no water comes out. Then measure the air pressure again with a tire gauge. That should be the precharge pressure that you applied. If you precharged it correctly and it has lost air pressure, then you have a leak somewhere; probably the tank. Precharge again if necessary.

    Then close all of the faucets and run the pump. The pressure should almost instantly rise to the precharge pressure; then take about about 1/2 minute to get from 38 psi precharge to 60 psi IF YOU ARE PUMPING 3.5 GPM.

    Observe the pressure on the gauge just before shutoff and immediately after shutoff. If there is a dramatic difference, then you probably have a flow restriction between the pump and tank.

    Measure the air pressure with the tire gage and compare with the water pressure gauge. They should be the same.
  8. Gary Slusser

    Gary Slusser That's all folks!

    BobNH, he said; "When the pump was first plugged back in the pump was cutting on and off rapidly ( about every second or so ) ".

    Plus, the pump and his current set up worked fine before he had the initial problem. It's designed for the pump to continue to run while there is water being used. Now you have him looking at the pressure tank size!

    The problem is in his raising the pressure switch setting too high for his old jet pump. Instead of 40/60 psi he should try 25/35, or 30/50 by simply adjusting the switch BUT... he first needs to redo the captive air pressure to 1-2 psi less than the cut-in setting he chooses and get a good water pressure gauge so he knows what the pressures are.
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