Irrigation help

Discussion in 'Irrigation / Sprinkler Forum' started by brehms, Mar 27, 2007.

  1. brehms

    brehms New Member

    Messages:
    3
    Like many others, I'm new at this. I have done plenty of other construction, but plumbing has always been one of my weak spots.

    My wife and I moved into a new house, in a new subdivision in AZ.
    The front and backyards were not done. The builder was having a landscaper do the front, and I designed a sprinkler system for the back yard. The whole property is pretty flat.

    I measured 80 PSI static, 15GPM. coming from the water spicket right where the main water line enters the house. Water meter = 1", water line into the house 1" copper.

    My design includes:
    2 zones (irritrol 205 valves) (7 heads in ea)
    14 heads (Hunter PS10) (6-360deg, 2-270deg, 6-180deg) @ 360deg x30psi = 1.59gpm.
    1" CLASS 200 pvc for main line (55ft zone 1, 70ft zone 2)
    3/4" CLASS 200 pvc for laterals. (70ft zone 1, 65ft zone 2)

    Adding up the heads gpm, per zone, should be ~9 GPM

    The contractor came and did the front yard, and installed 2 lawnlife 75ASV 3/4" anti-siphon valves. 1 for the drip system in the frontyard, 1 for my line in the backyard. I received a 40' 3/4" sch 40 line to the back, instead of the 1" I had asked for. The valves are attached to the main line using 6" of 3/4" copper.

    After the contractor did their work, we immediatly noticed that the water pressure inside the house was reduced. Also, the outside spicket where I took my original measurements, water seemed to not come out as fast. Even when the lawnlife valves are completely closed.

    There is a pressure reduction device, but that looks like it is connected to the drip system only.

    After I tillered, trenched, laid pipe, glued everything together, I flushed the pipes and noticed the water was only coming up about 5" (with all the other heads capped). When attaching the heads, I can only get 2x360 heads working (3.2gpm). There doesnt seem to be enough pressure or water.

    So my questions are:
    Where is my problem?
    Is it the 3/4" sch 40 line or 3/4" copper?
    Did I use the wrong size pipes or valves?

    I mostly used www.irrigationtutorials.com for my education, and it seems like everything should be fine.

    Thanks in advance for any help you may give.

    brehms
  2. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    Look for another shutoff valve(s) upstream of this work, maybe near the water meter. See that they're fully open.
  3. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    The analysis requires measuring flow and pressure at the same time.

    With 80 psi static pressure, you may have a regulator inside that will restrict the flow.

    Start with the house. Put a pressure gauge at the first place you can where the water comes into the house and measure the static pressure. Then turn on showers and faucets until you get 8 to 10 GPM as measured by the water meter and measure the pressure and flow (GPM). There is usually a needle that goes once around for 10 gallons or 1 cubic foot. One cubic foot = 7.48 gallons. Just count the seconds with a watch or clock for one revolution and do the calculation.

    That test tells you what the supply pressure is to your house.

    Then go to some farther-away place in your system, such as an outside spigot far away from where the water comes in and repeat the process. In this case, you should have flow going to the outlet so you measure the pressure loss in the pipe coming to that point. For this case, you could put the pressure gauge in the irrigation system (before the valve) and run the flow through nearby outside faucets.

    Finally, try to run your irrigation system with everything else turned off, and measure the GPM. While that is running, measure the pressure (1) at the source coming into the house, (2) at a point just before the connection to the irrigation system, and (3) at some point in the irrigation system.

    Those three measurements will tell you where you are losing pressure, and will tell you how much the system will deliver to the irrigation system.

    The answers to your questions will probably be apparent after you run the tests and look at the data. If you have any more questions, come back here for another shot at some answers.
  4. brehms

    brehms New Member

    Messages:
    3
    Thanks, I will give that a try when I get home tonight.

    1 other thing that someone mentioned was the fact that I have 2 valves downstream of the anti-siphon valve. I was told that may create some back pressure, and be dangerous.
  5. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    No valves of any sort are permitted downstream of an antisyphon valve. Even sprinkler heads with check valves are no go. The water must be free to drain away from the AS valve's vacuum breaker when the zone isn't running.
  6. brehms

    brehms New Member

    Messages:
    3
    I figured it all out.
    It turns out the contractor who did my front yard, turned down my water meter from full open to 1/2 open.
    The city turned it up to full open, and it runs great.

    What I am planning to do this weekend is pull out the 2 manual ASV's and install 3 Auto/man ASV's as well as run a 2nd line to the back yard. So that's 2 ASV's for the back, and 1 for the front drip system.
    I'm also going to install a isolation valve so I wont have to turn the water off at the meter anymore when working on any lines.

    Attached are 2 pictures of what is currently installed.
    I'll post a few more pic's when I am done.

    Thanks again for the help.

    Attached Files:

  7. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    You won't regret making the effort to bring it up to code. By the way, if there were still any issues of low pressure, you could use (good brand-name) plastic AS valves in place of those brass Lawnlifes, and gain some pressure, since those brass AS valves have high friction losses.
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