well pump cutting on and off.

Discussion in 'Irrigation / Sprinkler Forum' started by rikmoor, May 28, 2012.

  1. rikmoor

    rikmoor New Member

    Messages:
    7
    Location:
    Wilmington, NC
    So I have just finished installing and calibrating my do it yourself irrigation system. And after a few days of flawless performance, my pump is now acting up. Let me caveat with I have a digital timer and solenoid valves where I should be able to run this fully automatic. But I have a small leak in my manifold I haven't fixed yet so I have been operating it manually. I did not install the pump relay as I don't fully understand it and my thoughts were that when left in auto mode, the pressure switch on the well pump should turn the pump on and off as necessary. When all 3 valves are closed, pressure is maintained at 65 psi and will not run, when the system pressure drops below 20 psi, the pump will kick back on from the pressure switch. And it worked fine like this for about 3 days.

    However now my pump is kicking on and off repeatedly when trying to irrigate a zone. The gauge pressure jumps up to about 50psi, pump kicks of, pressure drops below 20psi, pump kicks on - and this repeated on and off cycle is in fractions of seconds. So the stream coming out of my heads is pulsating with the pump motor as it kicks on and off. And the worst part of troubleshooting, this doesn't happen every time. But right now it is about 50/50.

    Well pump is the Myers HJ100D and the timer is Rainbird SST-900i.

    I just put out 6 pallets of St. Augustine sod on Friday...please help if you can. Thank you in advance!!!
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,164
    Location:
    NW Ontario, Canada
    What size pressure tank do you have? Try turning up the kick-out pressure to keep the pump running.
  3. rikmoor

    rikmoor New Member

    Messages:
    7
    Location:
    Wilmington, NC
    Since this is purely to feed an irrigation system that is capable of delivering adeuate flow and pressure with a continuous running of the pump, I did not install a pressure tank. During irrigation, this tank would never fill to provide pressure. My zones are running at 10 gpm therefore this pressure tank would merely be a "flow-through" device. And if it did build pressure intermittently, I wouldn't want the pump cutting on and off that frequently. Because unless I had a huge pressure tank, the pump would kick on and off every minute or so. The cycling would be too rapid in my opinion.

    These are just my thoughts - I'm a civil engineer so I'm not totally uneducated in the logic of how these things should work, but I'm not a specialist in irrigation by any stretch. Feel free to correct me if my logic on the pressure tank is flawed.

    I may try what you said and increase the pressure on the switch to something higher than the current limit of 70psi and see if that makes a difference. Is there a max pressure that I should be using here? When I get this thing working in fully automatic mode, I hate to have it sitting idle between irrigating cycles at something like 100 psi.

    Thanks again for the help in these forums!
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    And if you don't have a tank, the pump will kick on and off every second or so! Never use a pressure switch without a pressure tank. And no matter the size of the tank, every zone has to exactly match the outout of the pump or the pump will cycle itself to death. You have three choices....

    1) Add a pressure tank and make sure every zone matches the output of the pump.
    2) Add a small pressure tank and a CSV, then you can make the zones any size you want.
    3) Use a pump start relay from the irrigation controller instead of a pressure switch.
  5. rikmoor

    rikmoor New Member

    Messages:
    7
    Location:
    Wilmington, NC
    10-4 valveman. Hear ya loud and clear. I am going to go the route of the pump start relay. So to disconnect the pressure switch, do I just need to remove the tube that connects it to the pressure regulator? And do I need to physically remove it from the pump? Best I can recall it was integral to the power supply connection to the pump itself. Also, is it safe to assume the pump start relay will come with a wiring diagram that shows how it connects to my power source and pump? I read a little on the Rainbird tech support for troubleshooting and have a basic understanding of how it will be installed, just want to make sure it is a DIY level project. I am using a 230V power source for my pump and will obviously turn the breaker off at the power panel and disconnect at the pump before working on any of this.

    As I understand it, this relay will ensure that the pump is not maintaining pressure in the lines unless their is a zone activated by the timer. This is by far the best route since I don't really want/need to have a pressurized line from the pump to the manifold. So I'm actually pretty excited about this addition anyway.

    Thanks again for the help.
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    You don't have to remove the pressure switch. Just move the wires from the pressure switch to the pump start relay. Also need a good pressure relief valve. Pump start relays will still start the pump, even if the varmints eat the wire going to the sprinklers. A pressure relief valve will help keep the pump from melting down when this happens.
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