Installing a Rain Sensor

Yet another rainy day here in the Northwest Florida Panhandle. Not only are we dealing with the rain, but it's cold too! I shouldn't complain too much as our winters down here are very mild compared to many other parts of the United States.

The rain reminds me of a common problem that I see with many sprinkler systems; no rain sensor installed on their irrigation system. There is just no reason for this, as installing a rain sensor is pretty easy and the cost is not that great. You can purchase a good rain sensor for around $30 and most can be hooked up in less than an hour. If you are hiring a company to do this for you, you can expect to spend around $115, but the savings it can bring you in the long run far outweigh this small investment.

Those who have system connected to city water or a metered water supply must pay for the water they use through their sprinkler system. Some areas even charge you sewer cost on the gallons used even though the water is not going in the sewer. Some cities (but not all) will provide you with a separate meter for irrigation so that you only pay for the water usage and not the sewer costs.

Even if you have your own well & pump you should consider putting a rain sensor up. Although you are not being charge for your water on a private well, you still should not water when it is raining! Excessive watering can cause root rot and make for an unhealthy lawn & landscape. Excessively wet conditions can also cause fungus or mold.

All the major irrigation parts manufactures have rain sensor. Rain Bird, Hunter, Nelson, and Toro all have their own versions, but they are very similar and produce the same end result. All rain sensors are connected to the system in the same way. New digital timers come with a spot on the wiring terminal that says "sensor". There are two screw spots on the sensor terminal. Rain sensors have two main wires or leads. All you must do is hook one wire up to one side and the second wire to the other side.

Older digital timers without sensor spots will require you to put a "break" in the common wire. All you must do is take the common wire or wires off the "com" spot on the timer and hook up one of the rain sensor leads in this spot. Then take the common wire or wires and wire them together with a wire nut to the other rain sensor lead. Pretty easy! The most time consuming part of this is mounting the rain sensor and routing the wire.

The edge or eve of the house is a popular spot to mount the rain sensor. A wooden fence is another option. Just remember to mount the sensor in a spot where it is clear of trees and other obstructions so that the rain can directly hit the sensor. The rain sensor can then be set by a simple adjustment to shut off the system at anywhere from 1/8" to 1" of rain. Your particular setting will depend on your landscape, soil condition, climate, and weather. We set most sensors down here to shut off at 1/4" to 1/2" of rain.

The sensor will dry out at approximately the same rate as the soil and then let the system go back to active or to its' regular program. If you do not have a rain sensor installed, then go do it! Stop wasting water and protect your landscape. If you do not feel comfortable doing it yourself, then hire a licensed irrigation contractor.

Scott
http://www.autolawnsprinklers.com

How To Wire a Sprinkler System

Automatic lawn sprinkler systems are run by a combination of mechanical parts and electrical components that work in harmony to help produce the end result of hassle free watering. A modern irrigation system makes use of electric valves, solid strand wire, and a digital timer to make this process seem almost magical.

Once you learn how a system works, there really isn't much to it, although when you are trying to troubleshoot electrical problems on a system that wasn't built to code you can run into a few frustrations. But a basic understanding of how the electrical part works can greatly help you when trying to diagnose a problem.

Most standard digital controllers or timers run off of 110/120 volts AC. Indoor timers can be plugged straight into a common house electrical outlet, while the outdoor timers will need to be hard-wired from the transformer to the breaker. A single pole 10 or 15 amp breaker from your service panel (normally by the electric meter) supplies the main power source. With approved 14-2 or 12-2 insulated HV wire, the 110 volts is sent to the transformer on the timer. The transformer than steps-down the power from 110 to 24 volts (approximately). The main circuit board or "computer" part of the timer runs on this lower voltage.

The digital timer then has modules or individual spots for different wires that are labeled. Every zone has its' own spot represented by a number. Zone one is "1", Zone 2 is "2", etc... Different brands or models of controllers label this slightly different, but you can easily tell what each spot is for. The master valve is normally labeled "MV". The Common spot is labeled "com".

If you are on a pump/pump start relay system then the master valve spot will definitely be used. If your system is on a pressurized water source then the "MV" spot may be blank unless a true master valve is installed, but it is not necessary and many systems do not have a master valve. To simplify this brief explanation we will assume that there is no master valve.

Okay, each zone on your system has its' own electric valve. Each electric valve has a solenoid with two wires coming from the top. You will use 18 gauge solid strand wire for the system. Since you will need multiple wires it is best to use multi-strand wire. Multi-strand is a group of single, insulated strands of wire grouped together as one for ease of use. Black insulation is the typical cover over the single different colored wires. 18-5 is a group of 5, 18 gauge wires. Each wire will have its' own color such as white, black, blue, green, and red. Most contractors use white for the common wire and the other colors for the hot side.

Now back at your timer you would peel back the black insulation and then strip about 6" of the insulation on the white strand. Then secure the white to the "Com" or common spot by placing screwing down the contact screw or pressing in the clip on other timer models. Then let's say you want to use blue for zone 1. Wire up the blue strand to "1" or zone 1 spot on the timer. Back at the electric valve for zone 1 you would take one wire lead from the solenoid and splice it together with the white wire using a wire-nut. Take the second wire from the solenoid and splice it together with the blue strand. It doesn't matter which wire from the solenoid you use for either the hot or common, as long as each is individually wired.

The common wire is kind of like a negative. It is called common because it is common to all of the valves. Each valve in your system can share the common wire, but each must have its' own individual hot or colored wire. So let's say you have 4 zones. You would need 18-5 strand wire at a minimum. Each valve's hot wire + the common. I like to have an extra strand or two available at the valves for future use encase you want to add/split a zone, or to quickly fix any wire issues that could develop in the future.

If you are troubleshooting wiring on a system make sure to check what colored wire was used for what zone and the common. Not everyone uses white for the common, some contractors use green. To make things more complicated, some systems end up with wire splices in the ground and for some reason there are people who mis-match the colors either on-purpose or out of sheer ignorance which can make wire troubleshooting a nightmare! However, when installing or wiring your irrigation system I recommend that you stick with the same coloring scheme if you have to make a splice.

Scott
http://www.autolawnsprinklers.com

Lawn Sprinkler Design

When designing a lawn sprinkler system, the first thing that you must do is to determine a head layout. This is where you plot where each individual sprinkler head will go on your lawn. This can be done on a plot or drawing, but must also be done using mark-out flags in your actual yard. Use different colored flags to represent different zones or sections of your yard.

The two main kind of sprinkler heads you should be using on your lawn will be fixed spray heads and rotor heads. Spray heads don't rotate and put out water in a defined pattern depending on the nozzle that you select to install on the head. Rotor heads also come with different size nozzles for amount of water distributed, but rotors throw an average of 30 feet. I use rotors in areas where the heads can be spaced out from 25 - 35 feet.

You must keep rotors and sprays on separate zones since they have different precipitation rates. Sprays put out water about three times faster than a rotor head, so they saturate an area faster. If you mix rotors and sprays you will end up with parts of your lawn having to be either over or under-watered. So to avoid this problem, just make sure when doing your sprinkler head layout to section the yard accordingly.

Another important key to lawn sprinkler design is to have head-to-head coverage which will help accomplish even-precipitation. Head-to-head coverage is where the water from one sprinkler head reaches to the next sprinkler head. If the heads are spaced too far apart you will have gaps, hot-spots, or just uneven watering.

Pipe sizing is another factor that you must determine when designing your irrigation system. The size pipe you will need for your mainline and lateral line will depend upon the volume and pressure of the water source you are working with, plus the layout and volume each individual zone on your system demands. There are pipe friction loss charts which can be found to assist you with these calculations. In my e-book I describe a simplified design process that will eliminate the guess-work for you and works great for almost all residential sized systems.

Designing an automatic irrigation or sprinkler system for your lawn and landscape is not rocket science, but there are a few things that you must understand and apply to get it right. Most people who come in to the project with the right knowledge, tools, and time can easily complete their own project.

Scott
http://www.autolawnsprinklers.com