Too many head for a zone?

Discussion in 'Homeowner Assistance Forum' started by iTom, Apr 25, 2013.

  1. iTom

    iTom LawnSite Member
    Posts: 8

    Hello,

    I currently have a zone near my driveway with 6 heads in it. The sidewalk grass never had irrigation in it and I am planning to extend the driveway zone to the sidewalk. According to my calculations, I would need 7 spray heads to cover the sidewalk grass. These would probably be Hunter heads (the ones designed for sidewalks) The first 6 heads are all spray heads and the water line runs downhill, so I don't think much pressure is being used. So is 13 low velocity spray heads running down hill too much for one zone? My area has good water pressure by the way. If there is not enough pressure, is there some valve or gadget out there that will give the necessary boost?

    Thanks!

    Tom
     
  2. 1idejim

    1idejim LawnSite Fanatic
    Posts: 8,858

    Start by finding your supply (GPM)

    Next, calc your demand (GPM)

    Measure your pressure (PSI)

    A little math will tell you.
    Posted via Mobile Device
     
  3. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,608

    I'm dreaming that you have some spare controller wire and a mainline close, it should be a separate zone.
    That has been the biggest problem I've seen in amateur systems; never planned for expansion. :hammerhead:
     
  4. bx24

    bx24 LawnSite Senior Member
    from MA/TX
    Posts: 503

    You need to do some homework on what is "good pressure", pressure lose(s) at locations, nozzles per zone, GPM before and after backflow, after valves etc....

    Putting in systems is like working at walfart with some basic math but you are a little off.
     
  5. iTom

    iTom LawnSite Member
    Posts: 8

    Okay, I will run the numbers. I can't really run another zone because it would require a trench to be dug 270 degrees around the house to the valve box. The landscaping is already in. Ouch.
     
  6. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,758

    From a profession standpoint and the actual right things to do

    Couple things to factor:

    Measure your Static Pressure
    Measure your Dynamic pressure when the zone is running

    - It would be nice to know your maximum water flow rate. Though just keep it standard to water flow rates for pipe size
    -Calculate your current water flow on the zone
    -Inspect Water meter size, More importantly inspect zone pipe size.
    -Follow water flow rates based on pipe size and FPS ( Feet per second) Try to keep it under 5-7 FPS to help prevent water hammer ( Follow flow chart guide)

    - Can the pipe that you are extending support the additional water flow to the requirement of the new sprinkler head addition? Can the entire zone support this much usage with out going over recommended FPS?


    If there is spare wire available, spare room on the controller you can add a zone.
     
  7. 1idejim

    1idejim LawnSite Fanatic
    Posts: 8,858

    You have to understand that we can't see the system or do any testing. you have to do the leg-work
    Posted via Mobile Device
     
  8. iTom

    iTom LawnSite Member
    Posts: 8

    I do. I will hook up a gauge and check it out.
     
  9. bx24

    bx24 LawnSite Senior Member
    from MA/TX
    Posts: 503

    I ran into this situation on my own house. Had to run around 200ft of 1.25" pipe around my house to a 4-zone valve manifold to avoid pressure drops etc. That is part of the game. Not to hard if you do it correctly and not hack it. In the end, 107 Hunter heads and pipe cost me $1,800 and running pipe (1/4 mile) was about 2.5 hours with tractor attachement; can pull pipe at 8 mph!!!! All the sprinkler people wanted $8,000 to $10,000 to install...RIP off. Sorry I was in the business. Just as bad as he fert people.....$800+ for $200 of product.
     
    Last edited: Apr 25, 2013
  10. iTom

    iTom LawnSite Member
    Posts: 8

    It's not hard for the most part other than the multiple walkways, flower beds, steps, cement, and driveway I would have to dig under. I'm really hoping there is enough pressure.
     

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