How to Replace an Automatic Water Sprinkler System

Planning

• 1

  Contact local utility and cable companies to locate the underground pipes. Before any kind of digging project, it is advisable to locate the underground utilities to prevent damaging them. Apply for any building permits to install the sprinkler system with your local city building office. Since you are replacing an existing irrigation system, you may not need one.

• 2

  Measure the outdoor water pressure by screwing a water pressure gauge clockwise onto one of your outdoor spigots. Record the pressure in pounds per square inch -- or psi. Remove the gauge.

• 3

  Place a 2-gallon bucket underneath an outdoor spigot. Time how long it takes to fill the entire bucket using a stopwatch, to calculate your home's outdoor water flow rate in gallons per minute. For example, if it takes 20 seconds to fill the 2-gallon bucket, then the flow rate is 6 gallons per minute.

• 4

  Locate the water meter size on your municipal water system meter. It is either 5/8-inch, 3/4-inch or 1-inch and is printed on the meter. If you cannot find it, locate the information on your water bill. If your water source is different, locate your pump size.

• 5

  Measure the incoming water supply line pipe from the water meter to determine what kind of sprinkler pipe you need, using a cloth measuring tape. If your service line pipe is 2 3/4 to 3 1/4 inches in diameter, you need 3/4-inch sprinkler pipes; if it's 3 1/2 to 4 1/8 inches, you need 1-inch sprinkler pipes; and if it's 5 inches in diameter, you need 1 1/4-inch sprinkler pipes.

• 6

  Sketch a preliminary layout for the automatic sprinkler system by mapping the exact measurements of your home's surrounding plot. Use a measuring tape to determine the size of the front yard, side yards and backyard. On paper, designate zones on your map for each type of area, such as flower beds, grass and succulents. Draw out paved areas and fences. Determine how much sun each zone receives. Measure the size of each zone or area.

• 7

  Draw a final layout on graph paper. Scale the drawing to about 1 inch on the paper equaling 10 feet. Mark on your drawing where the water meter is and where the manifold -- or main irrigation valve that needs to be near the main water supply -- is going to be.

• 8

  Choose sprinkler heads or drip tube emitters for each zone. Select heads based on coverage needs in different areas. For example, pop-up sprinklers are used on lawns to cover large areas and retract to prevent damage from lawnmowers. Shrub sprinklers are taller than sprinklers for flower beds.

Installation

• 9

  Drive 18-inch tall wooden stakes into the ground with a mallet where you plan on placing sprinkler heads, using your final layout as a guide. Continue until all the proposed sprinkler heads are marked with an 18-inch wooden stake.

• 10

  Tie string along the stakes to indicate where the pipes run. Cut the PVC or polyethylene pipe into the lengths of the string, using a PVC pipe cutter. PVC pipes can be used in warmer climates, but polyethylene pipe is recommended in colder climates, because it is more flexible.

• 11

  Smooth all the cut edges with a metal file. Bevel the edges slightly using the file. Connect the pipes with pipe connectors, such as "L" shaped fittings, temporarily to create the overall layout. Connect swing joints where each sprinkler head goes.

• 12

  Dig trenches 6 to 12 inches deep and 6 inches wide with a square-headed shovel, following the string. Dig a 6-by-6-inch trench that is 3 inches deep for the preassembled manifold near the water supply. Lay 2 inches of gravel into it.

• 13

  Place the preassembled manifold on the gravel. Frequently, irrigation systems use a manifold with several valves to connect to more than one pipeline.

• 14

  Disconnect all the pipelines to form the permanent seals. Wipe each pipe end with PVC cement primer, using a rag. Then brush the pipe ends with PVC cement, using a 5/8-inch paintbrush. Insert the pipe ends into the connectors. Connect the swing joints the same way. Allow it to dry for at least 1 hour.

• 15

  Place the pipes into the trenches. Screw the sprinkler heads onto the swing joints, turning them clockwise. Some heads are fastened with screws, so read the manufacturer's instructions to determine how to attach your specific system's sprinkler heads.

• 16

  Screw the automatic sprinkler control box to an outside location that is near a power source. Since you are replacing a system, put the new control box at the same location so you can use existing wires. Turn off the circuit breaker for the control box, and connect the wires according to the manufacturer's instructions. Turn the circuit breaker back on, and then power the box on to check if it works.

• 17

  Turn the power off to the control box again, to connect it to the sprinkler system. Run 16-gauge wire from the manifold to the control box. Strip off 4 inches of the outer insulation from the wire on the manifold end. Connect the two colored wires from the manifold to the 16-gauge wire of the same color, such as red to red. Twist the wires together, and cap with a wire nut. One wire is used for each pipeline, so repeat the connection until all the zones are connected.

• 18

  Connect all the white wires together. Twist the connections together and cover with wire nuts. Press all the wire nuts into a wire organizer to protect them. Run the other end of the 16-gauge electrical wire to the control box. Connect them to the box according to the manufacturer's instructions. Turn the power back on from the circuit breaker and the control box..

• 19

  Shut off the main water supply at the water main. Secure a 12-inch garden hose to an outside faucet. Connect the other end to the manifold. Turn the outside faucet counterclockwise as far as possible. Turn the main water supply back on.

• 20

  Test the system by pressing "Test" on the control box. Cover all the pipelines with dirt.