Sprinkler System

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by statjunk, Aug 9, 2007.

  1. statjunk

    statjunk DIY Senior Member

    Messages:
    542
    Hey guys,

    I've never installed a sprinkler system and I'm not really sure I want to but at the very least I'd like to outfit the house with the means to have one in installed in the future.

    What size water line needs to be run to feed a sprinkler pump capable of irrigating 3/4 acre?

    and

    What amp service needs to be ran to power the pump? I'd rather go more than less (ie heavier guage wire since the run is quite short)

    Thanks

    Tom
  2. statjunk

    statjunk DIY Senior Member

    Messages:
    542
    I just realized there is a sprinkler forum. Can an admin move my post?

    Thanks

    Tom
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Sprinkler design is not difficult, but if you "wing it" and get it wrong, there is no fixing it. You will hate yourself forever.

    Design is based totally on how many gallons per minute you have available at a suitable pressure. You can start with known GPM max, which is based on testing the actual flow, or based on a pipe size, pump output rating, etc. Then you can do your design, which will provide the number of zones necessary so that you do not exceed that capacity at any time.

    If you know what supply you have available, there are charts which discuss GPM capacity of pipe sizes vs. distance. Then we need to know pump capacity.

    All the majors, Toro, Rainbird, Orbit, Hunter, K-Rain, etc. have on-line design help, and in many cases will provide a complete free design once you provide them the water supply specs. I definitetly suggest taking advantage of one of these.

    One of the major "rookie" mistakes, which will kill you, is to undersize mains and feeder pipes. This is a "fatal error" and can only be fixed with shovel! When you see a professional design plan, you will note all the pipes are probably one size larger that you would have selected. Go with it!
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,488
    Location:
    Cave Creek, Arizona
    pump

    If you install a pump to pressurize the irrigation system, you could cause major degradation in the house plumbing, if everything else is not sized to compensate for it.
  5. statjunk

    statjunk DIY Senior Member

    Messages:
    542
    I'm not sure if I'm not understanding you guys or it's the other way around.

    All I want to do is put electrical and water line access to the exterior of the house so that in the future adding a sprinkler system would be easy.

    Is a 3/4" water line sufficient for a sprinkler system?

    Also what amperage do the pumps run at? Are they 120 or 240?

    I just want to mount a disconnect and a valvue on the exterior while I have the wall exposed.

    Thanks for the input.

    Tom
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Whether you do it now, or later, it has to be right.

    3/4" supply would be small for a sprinkler system. If we uses a moderate assumption of 12 gallons per minute, could run 3 rotors, or 3 to 5 full circle fixed heads. This is why we emphasize the need for advance planning. If you started now with a small pipe, your sprinkler system would be failure before you got the first head in the ground.

    Pumps can be had that run on 120, or 240. Some will have the option to use either. You should look at some pumps to get an idea of amp requirements, and then get an electrician to put in the appropriate circuit.


    Here is a typical 1½ HP pump. Your electrician can tell you what is needed for 1½ horse/ http://www.waynepumps.com/prodlist.asp?pcode=WLS150
  7. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    How far is the house from the street? This is important, since the supply line to the house can be the major source of pressure loss in a lawn sprinkler system. If you were in a development in my region, you might find that the tapping of the water main in the street was already done before construction began on your home, so you might already have a 3/4 tap feeding a 3/4 copper line and curb stop, and the customary practice is to continue that 3/4 copper all the way to the house.

    If the above describes your supply, then you have an option, which is to upsize the copper from the curb stop. There are special adapter fittings that go on the outlet of a flared curb stop, that will mate with larger sizes of copper.

    If you're lucky, this supply line increase might allow you to do without a booster pump, and in any event, it will allow the pressure in the house to stay up, when the sprinklers are running.
    If the supply line is already in place, then you'd want to increase the pipe size to the system from 3/4 to 1 inch, since you will have 1 inch zone valves anyway ​
    Last edited: Aug 10, 2007
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,488
    Location:
    Cave Creek, Arizona
    irrigation

    Almost no irrigation system use a separate pump. They use a timer and valves and the city's water pressure. If you were to talk to anyone in a neighborhood where some people use booster pumps and the others don't, you would find a lot of unhappy people who get lousy volume and pressure when the pumps kick in and suck the water out of the main. That is what would happen to your house when the irrigation pump started, if it was not designed to accomodate a pump.
  9. statjunk

    statjunk DIY Senior Member

    Messages:
    542
    I'm going to interpert this as more trouble than it's worth. Wow I wouldn't have thought. I figured I could just tap the copper right past the meter and get that feed outside and things would go great from there. Guess not.

    Tom
  10. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I had interpreted your question as if you were on a well, or were going to pump out of a pond. If you are on city water, it is a much simpler question. Find out from the city what size meter pipe you have. That will determine the GPM available to design the sprinkler system from. Very important to use a large enough pipe from the meter that at full tilt, you do not have excessice pressure drop which would cause the heads to not work right.

    I don't think a pump would be called for, as it cannot make up for indadquate GPM from the meter.
  11. Mr_Pike

    Mr_Pike New Member

    Messages:
    136
    Location:
    Nebraska
    Cut in a T after the meter, then a main line of 1" soon after put a full port 1" ball valve, soon after that another T. one side of this T continues on up the wall and outside to the backflow preventor, the other side of the T should be plumbed to a drain valve of some sorts, a plug, a boiler drain or another ball valve.

    Unless you have horrible pressure there should be no need for a booster pump on a city water system if it is designed correctly.

    You can learn more about design at http://www.irrigationtutorials.com/
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