Sprinkler System Installation

DEAR MIKE: We've finally saved enough money to landscape our back yard. We have in mind a lawn and sprinkler system, but we've never installed such a system. Any suggestions? -- Nick E.

DEAR NICK: You can save several hundred dollars installing a sprinkler system yourself, but be prepared, you'll ache for a week. You'll spend at least $200 for material, depending upon the size of your yard, just for the sprinkler system. By the way, as long as you're doing this, you might as well make it an automatic system (sprinkler clock and electric valves).

You need to take a preliminary trip to the hardware store to gather some information. Most hardware stores have free layout guides that help you determine the number of valves you'll need, the amount of PVC pipe to buy, the number of heads you'll need, etc.

You also must locate where your sprinkler system is stubbed out. Typically, the builder installs the front yard's sprinkler system and will run the pressurized pipe to somewhere near the side of the house. It's a guessing game.

If you're lucky, you'll see the white PVC sticking out of the ground with a cap on it. If you're not, you'll have to dig from the front sprinkler valve box and follow the pipe until it ends.

The builder of my house stubbed out the pipe right in front of my block wall. You can imagine my enjoyment tunneling 2 feet beneath the concrete footing just to get water to the back yard. Ah yes, landscaping can be thrilling.

The bad news is that this job requires digging. You can use a either shovel and a pick (or a digging bar -- about $20), or you can take the easy way out and rent a walk-behind trencher for about $65 for a half-day.

The trencher is fast, but since it's the size of an average desk and heavy, you'll have to muscle it around a bit. Since the trencher comes on a trailer, you'll need a hitch on your vehicle to tow it home. What would have taken all day to dig by hand, will take only an hour or two with a trencher.

Plan on digging a minimum of 6 inches, and then cleaning out the trench with a trenching shovel (about $15). This shovel is about 5-inches wide, which is perfect for narrow spots.

After the digging, run the water from the stub-out to your new valve manifold area. You'll need to extend the pressurized pipe to wherever you have decided to locate the valves.

The pipes are typically three-quarters of an inch. From this pipe, you'll add three-quarter inch tees. However many valves you'll have is the number of tees you'll use to build the manifold.

Some contractors use a 90-degree elbow to run the last valve off of the pipe, but I would use a tee and run a short length of pipe from it and cap it, just in case you want to add another valve later. Use schedule 40 PVC (about $2.50 for a 10-foot length) and, after you turn off the water and cut off the stubbed-out pipe, extend the pipe to the valve manifold area.

The valves attach with a threaded fitting (wrap the threads with teflon tape), and the threaded fitting gets glued to the pipe.

When gluing pipes and fittings, use primer and PVC glue. The primer cleans the fitting and ensures a leak-free joint.

PVC cuts easily with a hacksaw, but make sure to remove the burrs from the inside and outside edges of the pipe before gluing them together.

Once the valves are on, turn the water back on. Open each valve one at a time to blow out any dirt or PVC remnants.

>From the valves out to the sprinkler heads, you can use Class 200 PVC pipe. It's cheaper (about 30 percent less), but the walls of this pipe are considerably thinner.

You can use this type of piping from the valves out, because it won't be under constant pressure like the Schedule 40 PVC that leads to the valves.

Using PVC elbows, tees and risers, run the pipe in the trenches to the sprinkler heads. Manually turn on the valves and test the system. Adjust any sprinkler heads as necessary and fill the trenches with dirt.

Finally, wire the valves to the sprinkler timer. The builder may have run the sprinkler wire to the stubbed-out pipe, in which case you just have to extend the wire to the new valves. If not, use waterproof wire nuts and splice into the sprinkler wire in the front yard's valve box (this assumes you have a few unused stations on the current sprinkler timer). Run the wire underground and back to the new valves. Open the sprinkler timer and match the unused colors from the wire to the unused terminals in the timer.

If you don't have enough unused terminals in the current timer, you'll need to buy an additional timer for the backyard valves, or buy a larger capacity timer to replace the current one.

The white wire is the common wire and runs to every valve. Each valve has two wires: one gets attached to the white common while the other is attached to the color you designate from the timer.

Once the wiring is complete, plant the grass, program the timer and ice down the lemonade.

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