Pump won't reach cutoff pressure

Discussion in 'Pumps and Tanks Well Forum & Blog' started by MJP, Jul 13, 2005.

  1. MJP

    MJP New Member

    Joined:
    Jul 13, 2005
    I'm glad I found this forum. I have a problem I can't seem to figure out. We have an old remodeled farmhouse with an old well. I don't really have many problems with it except if you run water to long sometimes it will lose its prime. It has been a dry summer so far and last wekend I used a pressure washer. When I noticed the water starting to spit I stopped using it. Now 3 days later the pump runs and will only get to 30 pounds of pressure on the guage never reaching the cutoff pressure, which is 40. I have to unplug it to stop it from running. Would this happen if the well water is low? The pressure switch setting are 20 / 40. Any ideas or advise will be appreciated.

    Mark
     
  2. Hube

    Hube New Member

    Joined:
    Sep 1, 2004
    Location:
    Ontario
    It may be that there is some blockage (crud) ator near the pressure switch. It may need cleaning. Turn off the pump's power, and check this pipe (tube) out.
    Post back with results, and if needed, we can advise further.
     
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  4. Gary Slusser

    Gary Slusser That's all folks!

    Joined:
    Aug 31, 2004
    Occupation:
    Retired
    Location:
    Wherever I park the motorhome.
    IMO you had a dry well condition, or a leak in the plumbing going down the well. The loss of prime proves that. If you allowed the pump to run very long (5+ minutes) in that condition, it probably caused damage to the pump impellor, seals etc..

    Gary
    Quality Water Associates
     
  5. MJP

    MJP New Member

    Joined:
    Jul 13, 2005
    I removed the tube and blew it out with compressed air. There was some crude when I first took it off. After putting it back on the pump ran up close to 40 pounds but didn't seem to want to cut off so I adjusted the cut off pressure to 38 and it seems to be working fine now. Thanks for the great advise. I really appreciate it.

    Mark
     
  6. Gary Slusser

    Gary Slusser That's all folks!

    Joined:
    Aug 31, 2004
    Occupation:
    Retired
    Location:
    Wherever I park the motorhome.
    If the tube was blocked the pump wouldn't (have) come on when it should, and then it wouldn't shut off when it should; 20/40. Cleaning the tube would stop that but your problem is that the pump isn't building over 38 psi of pressure; proven by your need to decrease the cut out pressure setting to 38 to get it to shut off. Adjusting the switch proves that the switch sees the pressure and that the pump can't build more pressure, so you still have a worn pump or leak etc.. Expect it to not be capable of reaching 38 sooner than later.

    Gary
    Quality Water Associates
     
  7. MJP

    MJP New Member

    Joined:
    Jul 13, 2005
    I think you're right Gary. It worked fine for a couple of days after cleaning out the line. Now it runs but won't reach the cutoff pressure again. I'm not sure if it's the pump or a possible leak. It seemed to hold the pressure when it did reach the cutoff, so I don't think it leaking, but not really sure. The pump did run for a while when it lost its prime too. I am still convinced the water level is low. It started acting up after doing a few loads of laundry. Any more ideas? Would it make sense to replace the pump and if so should the tank be replaced or just the pump?
     
  8. speedbump

    speedbump New Member

    Joined:
    Jul 15, 2005
    Occupation:
    Water well and pump tech.
    Location:
    Riverview, Fl.
    You didn't mention if this is a shallow well pump, centrifugal or deep well.

    Is the pump offset from the well or on it
    Do you have two pipes leaving the pump to the well or just one?
    This is a well isn't it???

    bob...
     
  9. MJP

    MJP New Member

    Joined:
    Jul 13, 2005
    It is an old well with a shallow well pump and 1/2 HP motor. There is only one pipe leaving the pump to the well. Also I read other posts and keep seeing about adjusting air pressure in the tank, I have looked at the tank and don't see any where to this. Are there tanks that don't use the bladder?
     
  10. speedbump

    speedbump New Member

    Joined:
    Jul 15, 2005
    Occupation:
    Water well and pump tech.
    Location:
    Riverview, Fl.
    The tank will have nothing to do with the pump shutting off or not.

    If you want to know how to set a tank up, I can copy a Q/A from my website and paste it here. I don't know if I can advertise here or not.

    Your water level has obviously dropped enough to keep the pump from making 40 psi. When it comes back up, the pump will do the same if you readjust the switch. Or you can get a better (bigger) pump that will do more pressure. Not all pumps are created equal. Some will only make 40 top end, some will do 70. hopefully the water level don't get to 25' or less. Then it won't pump at all.

    bob...
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Most modern pressure tanks use a bladder. There are some designed as air-over-water. Basically, you start out with the tank drained. The pump starts to fill the tank up, compressing the air (it is trapped by the design by where the input output lines are located I think). Before the tank is full, the compressed air pressure causes the tank to reach the cutoff point for the pump controller. The disadvantage of this type of system, is there is nothing to separate the air from the water, and eventually, air is absorbed by the water flowing through the system, and then you need to recharge it.
     
  12. Pumpman

    Pumpman Pump Sales

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    Apr 12, 2005
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    Owner - R.L. Peeks Pump Sales
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    So. Cal
    Since this is a shallow well pump, it's possible that the nozzle is plugged up. This will keep the pump from building pressure.
    Ron
     
  13. Ironworker18

    Ironworker18 New Member

    Joined:
    Jul 2, 2016
    Location:
    Ontario
    I am having the same problem. I bought a house and noticed the sand point. The pump had not been winterized and was cracked. My neighbour gave me a pump he used one summer only, looks brand new and had minimal sediment in it. Came with a small holding tank bolted to pump and a big tall holding tank.

    Pump pressure stays at 40 and will
    Not shut off. 1/2 shallow well jet pump.

    I don't know how long the point wasn't used for but after installing check valve and priming with hand pump, sufficient water came out.
    - I tried to run my sprinkler with pump running and at times it didn't even have enough pressure to turn sprinkler side to side.
    - ALSO, the original owner installed 3 underground pipes for water services from the point at 3 different locations...for this reason i installed a ball valve after both holding tanks.(so I can shut it off and let tanks fill in case of leaks in any of the 3 underground lines.)
    The pump primed fairly easy, water in clear pipe going from top of pump to line @ tank feels cold for first 10 min...but later warms up when pump is at 40psi. (I guess it's bc it can no longer fill the big tank so it just sits there bc when I ran sprinkler to try to clear all old sediment the pump suction line remained cold after 10min)

    I have an elbow 3" above check valve. Approx 7ft deep water table.
    Using a 1" 1/4 to 1" metal reducer over the check valve with metal 1" elbow to 1" pipe connection. The rest of the stuff going to pump is plastic 1" black pipe until right at the pump back to 1" 1/4 metal (had to use reducers again)..working with all the parts I had from old system.
    Thinking about going 1 1/4 steel pipe right from point to pump for the suction part. (My father uses plastic pipe on the suction part of his point but I don't think he has all kinds of reducers).
    All plastic pipe has two hose clamps on it.


    I hate knowing what the issue is. I know I put a lot of information in this text I'm just trying not to miss anything to get the proper diagnosis .
     
  14. valveman

    valveman Moderator Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    You could possibly have a suction leak but the water in the well could be too deep for a shallow well pump, or that pump can only build 40 PSI.
     
  15. Ironworker18

    Ironworker18 New Member

    Joined:
    Jul 2, 2016
    Location:
    Ontario
    My point is approx 8ft deep which is fine for the shallow well pump. It can't even keep up to my sprinkler. I don't know how long the sand point was unused for. Might have been a year... Might have been 5. I'm going to try to run 1.25" pipe all the way to the pump instead of 1.25 reduced to 1" and back to 1.25" at the pump fitting(worked with what I had which was 1" plastic pipe)
     
  16. Ironworker18

    Ironworker18 New Member

    Joined:
    Jul 2, 2016
    Location:
    Ontario
    Also does it matter how high my elbow is above the check valve?
     
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