Will this hurt pump

Discussion in 'Pumps and Tanks Well Forum & Blog' started by cameron, May 25, 2006.

  1. cameron

    cameron New Member

    Messages:
    16
    Installed a 3/4 hp 10gpm submersible in river to irragate lawn open discharge I am using craftsman extra large sprinklers 8500sq ft reccomends running between 30 and 50 psi. My question is I normally run 2 sprinklers tried three but will not run third one very well, I tried one sprinkler and it really threw the water, soaked the ground in no time covered 120 ft ciircle. I don't know if it is building up to much pressure for the pump if so will it hurt pump how can I tell when it is to much pressure for the pump or not. How can I tell when I am running the right pressure or not or is there a way to tell.
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    You should install a bladder tank with pressure switch but reguardless you can't be using more water than the pump will pump and that is what it sounds like you are doing.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,689
    Location:
    Cave Creek, Arizona
    pump

    Without a pressure control and/or an accumulator tank, you either use all the water the pump can produce, and the pressure depends on how much residual there is, or the pump builds to its maximum pressure and you just use a part of the possible flow. Neither situation is harmful to the pump as long as you use some of the water. The damage comes when there is no water flowing so the water overheats, turns to steam, and then eats at the impeller. You just add as many heads as you can until the flow becomes inadequate.
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,473
    Location:
    Lubbock, Texas
    Valveman

    As long as you are using at least 1 GPM, it will not hurt the pump. The less water you use, the higher the pressure in the system. While using only 1 GPM, this pump is producing 130 PSI on your irrigation system. At 5 GPM usage you will have 125 PSI and at 10 GPM you will have 100 PSI. This is why the sprinkler is shooting as far as it does. If you use 16 GPM this pump will only produce 51 PSI and the sprinklers will not shoot as far. Low flow will put lots of pressure on your pipe system but won't hurt your pump unless you use less than 1 GPM. You may be fogging water out of the sprinklers instead of a nice steady stream. Usually above 40 or 50 PSI, sprinklers go to fogging and a lot of your water just blows away in the wind. If you install a pressure tank and switch, you will half to use 16 GPM at 50 PSI all the time or the pump will cycle on and off repeatedly from 40 to 60 PSI. You could use a 50 PSI Cycle Stop Valve with the 40/60 pressure switch and tank so that you could run from 1 GPM to 16 GPM and the system would stay at 50 PSI constant. At 50 PSI constant you would need to use more sprinklers and put them closer together because they won't shoot as far as they are now. But, at 50 PSI it won't fog and waste as much water as it does now.
  5. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    You could also install a 200 lb. gauge in the plumbing to see what pressures you are getting. Then you will see what valveman is saying.

    bob...
  6. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I think you will find that all sprinkler systems are not created equal. Nor are the zones on many given systems. Living in Florida, I see all kinds of systems. Most of which cycle motors to death.

    Since I know it's human nature to do things (especially for the DIYer) the easy way, most systems are going to be left alone and some other fix be tried. Since cycling is the worse thing you can do to a pump motor. A CSV is a very inexpensive fix to the problem. This is considering a switch and tank are being used. If not, then a pressure release valve may be the best solution.

    Not many people know how to get their zones synchronized. And a lot of installers don't think it is necessary.

    bob...
  7. valveman

    valveman Moderator Staff Member

    Messages:
    4,473
    Location:
    Lubbock, Texas
    Valveman

    A Cycle Stop Valve has been my solution to ALMOST everything for about 13 years now. Before that I tried everything else you can think of. It is almost impossible for most contractors to match the irrigation to the pump, so it is even harder for the home owner. Even when the irrigation is set up to match the pump, someone nearly always uses a garden hose and ocassionally forgets to turn it off and the cycling continues. I also like to have a little cushion with my pump size. If I match the pump to the irrigation today, next year I have 1 or 2 percent wear in my pump, which make it pump less. Then I get a little wear in my sprinklers which makes them use more water, and now nothing matches anymore. If you can upsize the pump just a little bit, and use a Cycle Stop Valve to make it work like you want it to, then you are covered when there is a little wear in the system or if a garden hose is left running. Spent my entire life explaining that the pump burned out because it does not match the irrigation system. I never have to explain this anymore, because the Cycle Stop Valve is my answer to ALMOST anything.
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