Sprinklers Explained

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System Example

This is an example of what the layout of a front yard sprinkler system may be like. The laterals are color coded to avoid confusion.

  1. Residence
  2. Main Line
  3. Zone 1
  4. Zone 2
  5. Zone 3
  6. Stop and Waste
  7. Backflow Preventer
  8. Automatic Sprinkler Valves
  9. Pop-up Spray Sprinkler Head
  10. Rotor Sprinkler Head
  11. Drip Connection or Bubbler
  12. Wiring for Irrigation Valves
  13. Irrigation/Sprinkler Timer

Sprinkler Head Layout

Sprinkler head layout is perhaps the most important part of your personal installation. If you don't have a proper layout, you wont have good performance and you will likely waste thousands of gallons of water each season.

Head To Head Coverage

Head to head coverage is a term you will often hear when having a conversation about sprinklers. The easiest way to describe head to head coverage; Every spot in the irrigated / watered area needs to be covered by at least 2 sprinkler heads, and each head should throw water far enough that it reaches or slightly overlaps the adjacent heads. This is done by considering each sprinkler as a geometric shape. Each sprinkler head is rated with an ARC and Radius, this provides you with the shape you will use to determine coverage. The geometric shapes will all be based around a circle, while your layout will be based around a square or triangle pattern. This is where inefficiency come in to play, because you are trying to fit a round object into a square or triangle pattern.

Layout Examples


The shapes in the pictures are representing the space between sprinkler heads


Each sprinkler head used in these examples are full heads to help demonstrate how important layout can be.


As you can see, the triangle pattern (actually called a diamond pattern) is more efficient, but it is less common because it is more difficult to lay out. Most residential sprinkler systems are done using the square pattern.

Layout can actually be quite simple, if you don't over think it. I generally walk around a property with a measuring tape or wheel and place flags according to available products based on distance. Example; Starting with a corner, I measure one one side or edge of the area to be irrigated, and determine what type and size of sprinkler head will fit best. I then repeat this for every side/edge of the irrigated property, until I get an adequate layout to provide good coverage. I then transfer the layout to paper or my computer to see if I have missed anything obvious. I generally pull the property up on google earth or google maps and take a screen shot, then I use a simple drawing app to apply my layout. There is software that can aid you in setting up your layout, but it is expansive and it takes time to learn how to use it.


Measure the property for spacing of Sprinklers

Create a layout using sprinkler heads, use rotors for larger areas if possible.


This is an example of an actual sprinkler system layout


As you can clearly see, the layout is good, but there are still gaps in overlapping coverage. This is a common problem, but it is unavoidable.

Stop and Waste

This is a must in areas that have hard freezes. The stop and waste is a shutoff valve that drains the down stream water from a main line. It is generally installed at the point of connection that is leading to the sprinkler system (generally close to the meter or a building). The Weep hole allows water to escape when the valve is closed. Thus a stop and waste is regularly installed at a depth that is sufficient to prevent freezing of the live side of the water main.

For More Information About Stop and Wastes, Check Out This Video.

Backflow Preventers

A Backflow is required for any sprinkler system supplied from culinary water (Drinking water). If you are not familiar with Backflows you need to do some research for your particular area since there are different requirements for different areas.

Backflow Definition

Undesirable reversal of flow of a liquid, gas, or suspended solid into the potable water supply; a backflow preventer is designed to keep this from happening.

Why Do I Need A Backflow Protection Device?

A Backflow Preventer protects drinking water from becoming contaminated in the event of a loss in pressure from the supply.

Backflow Preventers Commonly Installed On Sprinkler Systems

PVB, Pressure Vacuum Breaker

The PVB is my favorite Backflow preventer to use. It is easy to install, meets the requirements for most sprinkler systems and water departments, and it is also the least expensive. As long as you follow the installation guidelines/instructions provided by the manufacturer, this backflow preventer provides a great line of defense from backflow. The only form of backflow that the PVB does not protect against is back pressure. It is never a good idea to use a PVB in a system that has any kind of pump or has any kind of secondary water supply.

RP, Reduced Pressure Assembly

The RP is the best protection available for Sprinkler Systems connected directly to a pressurized culinary/potable water system. The RP backflow preventer is also the most expensive option in most cases.

To Learn More Check Out This Youtube Video "What is Backflow"

Garden Spigot/Hose Bib

Garden Spigots are a great source for large volumes of water to be supplied with a garden hose. They tend to have more volume and pressure than a regular garden spigot. The most common use is for filling a pool or hot tub quickly

For more information Visit my Blog

Manifold

This particular setup has 3 valves (one Drip Valve kit and 2 DVF Valves, a Gate Valve to shut this valve bank down for minor repairs and a ball valve used as a winter drain.

Manifold Design

All Fittings Are PVC

  1. 1 Inch Tee Slip x Thread
  2. 1 Inch Close Nipple
  3. 1 Inch Union Threaded
  4. 1 Inch Close Nipple
  5. 1 Inch Valve DVF
  6. 1 Inch Toe Nipple
  7. 1 Inch Union Slip
  8. Optional Drip Filter
  9. Optional Hose Bib (Used For Winterization)

My preferred Manifold setups are 2-4 DVF valves, My preferred way to assemble the threaded components is to wrap the threads Three times with Teflon tape, then apply a small amount of thread sealant. Do not over tighten, if you use both Teflon Tape and Thread sealant, hand tight Should be sufficient.

Valve Wiring

Valve wiring can be simple, but it can also cause problems if not done properly. When wiring valves, use an approved wire designed for sprinkler systems. If you take a closer look at the wire, each strand is color coded to make installation easier. When wiring Valves you need to choose a color to use as your common. The common is generally the White wire, but I have depicted it as Blue in the wiring image, just to make it stand out. As you can see, the common connects to each valve, along with a different color of wire run to each separate valve. When I wire Valves, I always start by selecting one wire from each valve and connecting them to the common (there are 2 wires coming out of each valve solenoid, as these wires are connected to a coil/electromagnet, the polarity doesn't matter, so simply select a wire for the common and the other will be used to control the valve). Once you have the common connected, you will have one wire left for each valve. Simply connect a different color wire to each valve. The color doesn't matter, but I always stick to a color code to make it easier when installing the Clock / Sprinkler Timer.

My Color Code For Wiring

The colors for your wire may differ

Common White

  1. Red
  2. Yellow
  3. Blue
  4. Green
  5. Orange
  6. Purple
  7. Gray
  8. Black
  9. Pink
  10. etc...

Lateral Piping and Sprinkler Heads

Pop-up With Swing Joint

  1. Pop-up Sprinkler Head
  2. 1/2" Marlex coupled with 1/2" Funny Elbow
  3. Funny Pipe
  4. 3/4" Slip x 1/2" Thread PVC Tee coupled with 1/2" Funny Elbow
  5. 3/4" PVC pipe Schedule 40
  6. Optional 3/4" Slip x 1/2" Thread PVC Elbow
  7. Optional 1/2" Auto Drain (Generally only 1 installed at the lowest point of each zone)

Rotor With Swing Joint

  1. Rotor Sprinkler Head
  2. 3/4" Marlex coupled with 3/4" Funny Elbow
  3. Funny Pipe
  4. 3/4" Slip x 1/2" Thread PVC Tee coupled with 3/4" Funny Elbow
  5. 3/4" PVC pipe Schedule 40
  6. Optional 3/4" Slip x 1/2" Thread PVC Elbow
  7. Optional 1/2" Auto Drain (Generally only 1 installed at the lowest point of each zone)

Lateral Tee With Sprinkler Head Connection

  1. 3/4" PVC pipe Schedule 40
  2. 3/4" Slip PVC Tee
  3. 3/4" Slip x 1/2" Thread PVC Elbow
  4. Barbed Fitting for Swing Joint Attachment

Sprinkler Zone Layout Example

  1. Laterals For Separate Zones
  2. 1" PVC Pipe Schedule 40
  3. 1" Slip Tee
  4. 3/4" PVC Pipe Schedule 40
  5. 1" x 3/4" Slip Reducer Bushing

Sprinkler Zone Layout Explained

In this Sprinkler Zone Layout Example the pipe size remains 1" until the second Tee. After this Tee, the piping and fittings remain 3/4 inch up to the Funny Pipe connections. It is a good practice for the pipe size to remain 1" (if the available water is 9-16 GPM) until the first Tee, or until the zone has supplied 1/3 of the sprinkler heads. In this example we will assume that the sprinkler heads are 1804's with Rainbird 15 nozzles. In that case this zone would be using 13.86 GPM, this rate of flow is to high for a 3/4" line to supply. Your objective is not to exceed 5 feet per second. It would be ideal to calculate the flow at each point in a system, but that is not realistic in most cases. Instead, I use a rule of thumb, I reduce the pipe size after I have installed 1 Tee that diverts the water relatively equally, or after I have installed the fittings that supply 1/3 of the sprinkler heads.

1/2" PVC

You may have noticed that I have not included 1/2" PVC. I never install 1/2" PVC, I run 3/4" to the last PVC fitting and at that point I use Funny Pipe. I find that this method saves a ton of time and has no adverse affects on the performance.

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