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How to Install a Home Sprinkler System

                

The installation of a sprinkler system is both labor intensive and requires attention to detail, as incorrect placement or spacing could lead to serious problems and much more work down the line. This article serves as a primer that can be referenced if you are considering installing a sprinkler system. 

Also see our post below for the layout guidelines to a sprinkler system!

Connecting the Water Supply

In order to supply water to the sprinkler system, the main water line will need to be tapped into. In some cases, the line was installed with a stub-out specifically for future irrigation. If this is the case, the back-flow prevention device can be installed at the stub-out. This is rapidly becoming the standard for new construction projects. In cases where no stub-out was provided, the main line will need to be tapped into with a compression tee and a stub-out installed. The water line is usually found by locating the water meter on the property, following the pipe direction for a couple of feet and digging down. If it is a cold weather climate, the main line can usually be found 3-5 feet deep. Warmer weather climates will tend to have the main line anywhere from 1-3 feet underground.

Marking the Sprinkler Head Positions

The next step for installation is mapping out the layout onto the lawn. There are a number of different methods for marking the layout. In most cases, the sprinkler heads are marked using wooden stakes or marking flags and the pipe network is designated using either string or marking paint. While the paint applicator and paint may be costlier, it can also help avoid issues with uneven or curved trenches.  This is an important step because it allows you to physically check to ensure that the distances between the sprinkler heads are correct, and that there will be no conflict when setting the pipes. If the initial layout was correct, the heads will be within the maximum distance of each other, providing total coverage. If a redesign is needed, it is best to take the time to do it now before the trenching and installation is finished.

Preparing for Trenching

It is advisable at this point to contact the utility locator service for the state. The name varies by state, but their intentions are all the same: to notify people of utility lines that may be running under their property. Having the center send someone out to mark the property is required in some states, but should be done in all circumstances. A worker will mark the lines on the surface using colored spray paint to indicate what kind of utility line it is. Using these markings as guidelines can prevent the damaging of a utility line while digging the trenches for the sprinkler pipes. If further incentive is needed, damaging a utility line and/or not having contacted a utility locator to mark the property usually results in a significant fine – and in some cases, a criminal charge.

If the marked utility lines interfere with the planned layout of the sprinkler system, adjustments will be needed. This may require a minor change in the branching of a zone, or to redesign the zones entirely.

Digging the Trenches

Once the property has been checked by the locator service and any lines have been marked, the trenching process can begin. Although the trenching process can be done by hand using trenching shovels, it is by far more common currently to use a automatic trencher. Plumbing or sprinkler suppliers may carry a trencher that can be rented as part of purchasing the necessary parts. If not at a supplier, many heavy equipment rental companies will have a selection of trenchers available. In comparison to digging the trenches by hand, the automatic trencher is far more efficient.

For warmer climates, the piping will only need to be 4-6 inches deep. In colder climates that can experience sudden hard freezes, it is better for the pipes to be deeper underground, anywhere from 8-12 inches deep. The deeper the pipes are, the less likely they are to freeze. When digging the trenches, they should be as narrow as possible, in most cases only 3 inches wide.

Installing the Controller and Valves

After trenching is complete, the valve manifold should be installed. Run pipe from the main line down to the area where the valve manifold will be. The next section includes information on connecting the two major pipe types to fixtures, and it may be advisable to review it before attempting to attach the manifold to the pipe. In most circumstances, installing the manifold so the valves are at ground level will be sufficient, however if using anti-siphon valves they must be 6 – 12 inches above the highest sprinkler head so the back-flow prevention systems work.

The sprinkler controller is essentially the brain of the system and is usually mounted on an exterior wall of the home near the sprinkler valves. This device will control the activation and shutdown of each valve and their associated zone.

Assembling the Pipes and Wiring

Once the controller and valves are installed, the piping can be assembled. In general, it is a good idea to start from the valve manifold and piece together the pipe system from the manifold out to the individual branches of the system. If the system was designed with PVC pipe in mind, the standard tool for connecting pipes and fittings is PVC cement. PVC primer can also be used, but it is not always required. It is best to check local plumbing codes on the requirement of using PVC primer. Using PVC cement (and primer, if desired), connect the pipes to their fittings and expand the grid out from the source to the end of each branch. When installing, it is important to try to avoid allowing dirt from the trenches into the pipes being assembled. If the system was designed to use PE pipe, the fittings are inserted into the PE pipe and stainless steel clamp is tightened around the PE pipe to keep the fittings in place. A rapidly growing alternative is to use specific fittings from Blazing Products that have been specifically designed to be quick to install in PE pipe and do not require clamps.

If considerations are being taken due to the system being installed in a cold climate, now is the time to install them. If using drain valves, this will require installing an additional tee for each drain valve. if an air compressor adapter was planned, the drain valves are not required but can still be used. The adapter should be installed before the valve manifold when attaching the valves.

Once the grid is finished and connected to the water supply, but before the sprinkler heads are installed, it is important to flush the system to clear the pipes of any dirt that may have found its way into the piping. After turning on the water for each zone for about two minutes, the pipes should be clear and the trenches can be refilled.

The wiring of the system will extend from the controller down to the side of the residence and into the trenches until it reaches the valve manifold. As such, it is important to use 18-gauge wire that can be buried. If installing a system that uses multiple valves, be sure to order wiring that has strands equal to the number of valves plus one. The wire will have one strand that connects to each individual valve back to the controller, and the remaining strand – referred to as the common wire – connects all of the valves to the controller in a single chain.

Filling the Trenches and Attaching the Sprinkler Heads

At this point, it is recommended to begin refilling the trenches. It is not necessary to completely fill the trenches quite yet, but rather only to cover the pipes. Leave space near the sprinkler risers to install the heads. Once the pipes are buried, it is recommended to do another flush of the system to ensure that there are no blockages. Leave the water on in each zone for around 2-3 minutes to ensure thorough flushing. After the flushing process is complete, the sprinkler heads can be installed. Ensure that the proper nozzles are being used and that they are adjusted to match the design of the system. Once the heads are installed, activate each zone again to ensure the sprinkler heads are all working. Adjust the spray patterns on each nozzle to ensure they are overlapping with adjacent sprinkler heads. It is also necessary to adjust them if they are spraying the house, sidewalks or other areas that should not be watered. If something is wrong, you may have to dig up the pipe for the particular area and re-check the connection. If nothing went wrong, then the installation is complete.

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