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Creating Water-Proof Irrigation Wire Connections

Tuesday, January 8th, 2013

Water-proofing your irrigation system’s wire splices is one of the most critical tasks in any installation or repair that involves wire splices. The splices need to be completely water-proof. Taping them up with electrical tape will NOT work for this! The electrical tape will allow water into the splice as it becomes old, brittle, and the adhesive on it dries out. If you don’t water-proof your splices it WILL cause your valve to fail! Don’t save a buck on a wire splice and ruin a $20 valve! I’ll explain in detail why waterproofing is so important later, first let’s get down to the details on how to make a good waterproof wire splice.

General Things That you Need to Know about all splices!

Caution: The methods described below are intended for low-voltage wires of 24VAC or less, such as those used in typical irrigation system controls. They should not be used for higher voltages.

DO NOT BURY SPLICES directly in the ground. Put a box around them to protect them and to help you find the later. A small plastic utility box works fine. Glue a large steel washer to the bottom of the box lid using epoxy. This will allow you to find the box with a metal detector if grass grows over it. Splices are the most likely place a wire will short out in the future, so a box makes the splices easier to find and repair.

2-wire irrigation systems: These are a newer type of system that uses only 2-wires to control all the valves. The irrigation controller sends a signal through the valves to a decoder at each valve. The decoder then allows power to the valve solenoid only when told to by the controller. These types of systems depend on electrical “signals” sent from the controller through the wire to the decoder. Any voltage leak at a splice can severely impact the signal and cause the system to malfunction. For this reason splices for 2-wire systems need to be made much more carefully. Many of the 2-wire manufacturers have specific splice methods they require be used in order to protect your warranty. Be sure to use these if required!

Not sure if your system is 2-wire? As i write this in 2013, 2-wire systems are seldom used on residential systems, but they are also gaining popularity and will probably start showing up soon, first on larger systems. The controller case normally will be clearly labeled as “2-wire”. A 2-wire system will also have a “decoder unit” installed on the wires at each valve. Standard irrigation control systems have two wires going to each valve. But in a standard system one of the wires goes to a single valve and only that valve. So if you have 4 valves there will be 5 wires (1 common shared by all the valves, + 1 individual wire to each of 4 valves = 5 wires.) On a 2-wire system with 54 valves there would be only 2 wires and each valve would have a decoder unit installed on it. The presence of a decoder to be installed at each valve is the best way to tell if it is 2-wire.

The best way to make the splice is to use special water-proof splice connectors that you can buy at any hardware store. These are made for sealing outdoor wire connections and work very well. There are many different styles and types available.

Water-Proof Twist On Connectors – “Nut” Style or “Wing” Style

Most of the connectors currently used by pros consist of an twist on type wire connector that is filled with a water sealing grease. Sometimes these are called water-proof “nut” or “wing type” connectors. These are inexpensive and very simple to use. Here are general instructions for use since a lot of these inexpensive connectors are sold without instructions. If instructions came with the connectors please use those instructions, as they are intended for the actual connectors you bought!

For every 3 connections you need buy 5 connectors. Why? Because you will probably make several bad splices, and you will have to remove those connectors and toss them in the trash. They can’t be reused because when you remove them a lot of the sealer comes out with the wire. (If you look close most connectors actually say “do not reuse” or similar language on them.)
Start by stripping the insulation off the end of the wires to expose the bare metal wire. Do not strip off too much insulation, the exposed bare wire should be about 1/2 the length of the connector body. You can splice 3 wires together easily using a single connector. It’s OK to put 4 or 5 wires in a connector, but be warned that it gets a lot more difficult getting the wires to stay in the connector when you use more than 3 wires.
Place the bare ends in one hand and using your other hand, align the wires side-by-side, so the ends of the bare sections are lined up together. Those ends need to all go into the connector together at the same time, so hold the wires tight and don’t let them slip out of position. Do not try to insert an additional wire into a wire connector that already has wires spliced together in it. You need to remove all the wires and redo the splice to add more wires.
Push the connector down over the bare ends of the wire. Twist the connector clockwise to screw it on. Hold the wires firmly in position as you twist the connector over them. The connector has threads, a spring, or barbs inside it that will grab the wires and cinch them together tightly as you twist it on. Stop twisting when you feel substantial resistance.
Hold the connector in one hand and tug on each of the wires with the other to make sure the wires are secure and will not pull out. If a wire feels loose or pulls out, disassemble the entire splice and try again. Use a new connector as some of the sealer will probably be lost when you remove the connector, and it needs all the sealer for a good seal. If the wires still pull out after another try you are probably using the wrong size connector.
Finally make a visual inspection of the splice. The insulation on the wire should be fully inserted into the sealer gel or grease. No bare wire should be visible. That’s all there is to using twist on wire connectors, they are very quick and easy.

The connector size is important when using twist on connectors! Be sure you buy and use the correct size connector for the wire sizes you are splicing. The package will list the various wire size combinations that the connector works on. The connector colors indicate the connector’s size and most are standardized. Here are some general guidelines. Warning: There are some brands that do not follow these color guidelines so double check the instructions on the package!

Connectors for #18 wire. Most residential irrigation systems use #18 size wire, this is the size of most of the multi-wire underground irrigation cables sold in hardware stores. Unfortunately the colors for these connectors are not standardized. Most I have seen are dark blue or black. Make sure it says it will connect 2- #18 wires.

Connectors for #14 & #12 wire. Larger irrigation systems and commercial irrigation often use individual #14 wires. Sometimes #12 will be used for irrigation systems with very long distances between the controller and the valve. Most often these connectors are yellow. Note: Most of the yellow connectors I have seen will NOT connect a single #14 wire to a typical valve solenoid wire. For this you will probably need the smaller #18 wire connectors above.

Twist-On Waterproof Wire Connectors. Wing Style on left (blue), Nut Style on Right (black).

Mechanical Clip Style Non-Stripping Connectors

Clip style is a catch-all name I use for the various types of connectors that use a mechanical clamping system to grab and bite into the wire. Typically with this type of connector you push the wire into a round slot on the connector, and then squeeze some type of clamp that bites into the wire to hold it in place. Some require pliers to squeeze the clamp into the wires. The most popular of these types of connectors for irrigation use is the Blazing Snaploc BVS Series wire connectors and the 3M Scotchlok 314 series connectors. These connectors are more expensive but make a very secure connection almost always on the first attempt. You won’t need to buy nearly as many extras for bad splices.

Container Type Connectors

These connectors are a two piece, two step system. You connect the wires together using either a standard twist type wire connector, a crimp sleeve, or even soldering the wires together. Then you shove the splice into a container filled with a water-proofing grease or jell and snap a retainer lid closed to hold the splice inside the container.

A variation on this type of connector is the original waterproofing method used back when I started in the business. You mixed a 2-part epoxy resin in a small plastic envelope and then shoved the splice into the envelope so it was covered in resin. The resin was allowed to harden creating a solid water-proof seal. Unfortunately the resin was a carcinogen. I don’t think these are sold any longer.

Tags: anti-siphon valve, installation, irrigation design, valves, Wire
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Pump Cycles On Briefly When Irrigation is Off

Thursday, November 1st, 2012

Q. My irrigation pump runs fine when the system is operating, but after it turns off it cycles on for 5 seconds every 10 minutes or so.

A. If you are using a pressure switch and pressure tank to turn the pump on and off my first guess would be that you have a water leak in your irrigation system. The water leaks out, which cause the water pressure to drop, then the pump kicks on and recharges the pressure. Then the pump shuts off again. That would cause exactly this symptom.

Knowing the problem is the easy part. Finding the leak, that could be harder to do. It could be a zone valve that isn’t turning off all the way or it could be a leaky pipe. You can narrow the search area a little, the leak will be someplace in the pressurized part of the system, that is, between the pump and the zone control valves. Start by looking for obvious dripping, then look for someplace that seems wetter than it should. If it is a leaky zone valve then the water will be leaking through the valve into the sprinkler zone pipes and will dribble out at the lowest sprinkler head. So look at the sprinkler heads. There will be a small “swampy” area around the lowest sprinkler head that is controlled by that valve.

Tags: drip irrigation, mainline, pressure sensor, pressure switch, pumps, repairs, Sprinklers, valves, well pump
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How to Find Buried Pipes, Wires, and Valves

Wednesday, September 19th, 2012

If you have an underground sprinkler system (drip systems too), somewhere out in your yard there are buried pipes, wires, and maybe even valves. But where are they? Sometimes they are above ground, so all you need to do is look around a bit. If not, then they aren’t visible because they are buried. (Big sigh.) You have perhaps the toughest problem there is in the irrigation repair business. There are no easy and inexpensive ways to find a valve (or pipe, or wire, the methods for finding them are basically the same.) But I can offer some tips to help.

Before we get going on how to find a valve let me make a couple of comments about what to do when you do find it.

Digging it Up

Once you find the valve you will probably need to dig it up. If you’re lucky it will be in a valve box and the box will not have been filled with dirt by some gopher. If there is a box be prepared to find critters inside the box when you open it! Use a shovel to pry the lid off from a safer distance. If the valve is not in a box, you need to be really careful when digging. Electric solenoid valves have wires attached to them that are very easy to cut with a shovel and very hard to repair once cut. Also if you hit the solenoid with a shovel you will probably break it and possibly break the valve as well. Even the valve body is easily cut as well as the pipe. So go slow and easy. Dig around the valve using a hand trowel. Better yet (I know this makes a mess!) you can use the stream from a garden hose with a patio cleaning nozzle on it to dig and use the water blast to loosen the dirt around the valve and wires. A plastic drink cup (ie; a McDonald’s cup) works good scoop out the muddy water and is unlikely to damage the valve.

If you cut or even nick the insulation off a wire, splice it back together using a water-proof splice kit made for underground wire splices. It is really important that the bare metal not be exposed to soil or water. Electrical tape will NOT work as a splice water-proofer! Use a special water-proof splice connector you can buy at any hardware store for ALL your irrigation wire splices and connections. Even ones above ground! If any water leaks into the splice it will corrode the wire. Even if the wire is not corroded through the corrosion can block enough electric current to make the valve not open. If the wire breaks or corrodes it will be a major pain to find where the problem area in the wire is. You will probably have to replace all of the wire. You do not want to have to do that! Water-proof those splices. Got it?

Be Prepared to Replace the Valve

There is a pretty good chance that if you can’t find the valve you will need to replace or repair it when you do. That’s just how the odds stack up. If the system is in such bad shape that you can’t find the valves, usually the valves are in bad shape also. At the least, the solenoid on the valve is probably dead or close to it. So prepare yourself now for that expense and effort.

Box It!

Once you find your valve, put a valve box around it! Irrigation valves are often marketed as “direct-burial”, but as you now know (or will soon discover), finding one that has been buried directly in the dirt is very difficult. It doesn’t need to be a big fancy box, they make nice little inexpensive ones that work fine. Even a used 1 gallon plastic plant container flipped upside down will make a decent temporary valve box until you can afford something better. It just isn’t a good idea to bury a solenoid valve directly in dirt. Besides the problem of finding it later, burying it can also make it fail faster. Plus you are a lot more likely to damage a valve buried in dirt when you dig it up for repairs. And all valves are going to need to be repaired someday! So put those underground valves in boxes, and while you’re at it, put 4″ of gravel under the box! The gravel keeps gophers from digging into the box from underneath and filling the box with dirt. You might also want to measure and write down where the box is located as measured from a couple of fixed locations, such as a house wall or fence. That helps you find it if grass grows over the top of it… if you don’t lose the measurements!

Ok, time to get to work.

How to Find a Buried Valve

1. Start by trying to figure out what the most likely place is where the valve would be installed. To do this you need to try to “get inside the head” of whomever originally installed the system. This helps cut down the “search area”. Do you know where other valves are in the yard? Are they each inside the area they water? If so, the others are probably inside the area they water also. Are they grouped together? Then the others may be nearby. Maybe there is a pattern to the placement of the valves, all on one side of the yard perhaps, or all in a row? If you don’t know where any of the valves are, you still know a pipe takes water to them. Find where that pipe connects to your water supply. Now try to figure out which way the pipe goes from there. Sometimes if you look real close you can see a slight indentation in the soil where the trench for the pipe was dug. Another tip, the grass is often just slightly greener where the trench was dug. For lawns, if you mow the grass short and look across the surface you can often see slight “troughs” where the trenches were dug and the soil has settled.

If you have the original plans for the sprinkler system they may help you find the valves, pipes and wire locations. If this is a commercial irrigation system the local building inspector or planning department may have a copy of the plans. However, even if you do have the plans, chances are the valves aren’t located where the plans show them. So I wouldn’t waste too much time looking for plans. In 35 years of practice and thousands of irrigation systems, I seldom saw the contractors install the valves exactly where they were shown on my plans. Even when I required my contractors to label and dimension the valve locations, I often discovered they just made up the dimensions!! At best a plan might give you a hint as to where to look.

2. If the valve you are looking for is an electric valve that actually still works, try turning the valve on and see if you can hear the solenoid buzzing or water whizzing through the valve. Try using a mechanic’s stethoscope placed on the ground to listen. Or cut the bottom out of a paper cup, place it upside down on the ground, and put your ear over the top. Do this late at night or in early morning to reduce background noise and make it easier to hear. Note; if the neighbors see you they will think you’ve lost your mind!

3. Try a metal detector if you own or can borrow one. I’ve honestly never tried this, but some people tell me it works, and it seems logical. Most valves have at least a little metal in them, although the cheapest ones have very little. The solenoid on an automatic valve has a bit of metal in it also. If you have, or can borrow, a metal detector you may be able to locate the valve or the wires with it. If the valve or wire are buried deep, a low cost metal detector will probably not find them. In my opinion the chances of success using a metal detector probably are not good enough to make it worth the expense of buying one. But if you have one or can borrow one, why not try it? I’d love to get your feedback on use of a metal detector if you try it!

4. Use a valve chatterer. This won’t work if the wires to the valve are cut or broken. So if you’re trying to find an automatic valve that won’t open, a chatterer is not likely going to help. A chatterer is a electrical device you put on the valve wire that makes the valve rapidly turn on and off. The result is that some brands of solenoid make a loud clicking or chattering sound that will give away it’s location. Unfortunately some valve brands don’t make much noise at all. And the deeper the valve is buried, the harder it will be to hear it chatter. Most irrigation pro’s have valve testers that include a chatter function along with other testing tools. These are handy tool for diagnosing valve electrical problems, but tend to be priced beyond what is justifiable for a homeowner to buy. (See ads for typical chattering devices at right. Also see my review of the Armada Pro48, which is the one I use.) To use a chatterer you disconnect the valve’s wires from the controller/timer and hook them up to the chatterer device. Turn the chatterer on and the valve should rapidly open and close and create a noise. Just like with listening for the water running through the pipe, you will have to go out in the yard and listen for the chattering, and it will help if it is during a quiet time of the day.

Make your own chatterer. All you will need is three 9-volt batteries and a friend with dexterous fingers. Someone who texts a lot on their phone is perfect! Start by making a valve actuator. Here’s how to make one out of three 9-volt batteries. To chatter the valve simply attach one of the valve wires to one terminal of your home-made actuator and tap the other wire against the other terminal of the actuator. Tap the wire at one second intervals. It doesn’t matter which wire goes to which terminal. The valve should turn on and off with each tap and make a clicking sound. I don’t recommend tapping the wires on the controller/timer terminals to chatter the valves. If you slip up while trying to tap the wires against the terminals and short circuit the wires you can damage the controller/timer. Destroying an expensive controller will ruin your day!

5. Water Dowsing, aka; water witching. This is a method of finding a water filled pipe by walking slowly while holding a branched stick or a couple of bent wires in your hands. I won’t try to explain how to do it, you can look it up if you want to try it. I’ve never witnessed it done successfully firsthand. But I have met several people over the years who have either seen it done successfully or done it themselves successfully. This includes people I trust, so I’m not in doubt of their claims. Now did they see or do what they thought they did? The answer to that thorny question I will leave to you to decide!

OK, the science behind dowsing is very shaky- at best. Most explanations I have heard are that those with the talent are able to read subtle signs on the ground surface that indicate the location of water or the pipe. They then subconsciously transfer that information to the movements of the sticks, like a Ouija Game. Everyone I know who claims dowsing works or that they have the ability to do it IS an expert who has worked in the industry many years. I can tell you that with 35 years of experience I can often look at an irrigated area and tell you where the pipes are with reasonable accuracy. No sticks needed. Just lots of experience looking at irrigation systems, and hints like those I’ve already covered, dips in the ground surface where trenches have settled, areas that are greener than others, etc. At any rate, I don’t want to get into any arguments over dowsing. I present it as an option that many believe works. If you can find someone with the talent, they may, or may not, be able to help you find the pipes, valves, or wires (yes, some dowsers claim they can find wires too!)

6. Use a wire locator (aka; wire tracer) device. This is how the pros do it, but if you notice the cost of a wire locator (ads on right), you will probably find that if you are a homeowner it is not within your budget! Some tool rental places, especially those that cater to professional contractors, have wire tracers they rent. (Sprinkler Warehouse rents wire tracers using overnight shipment.) You use a wire tracer to follow the path of the wires to the valve, starting at the controller/timer. Again, if the wire is broken you may not be able to follow it (although the better units can even jump the signal over small wire breaks. However, it will find the location of the break so you can repair the break in the wire. Then you can continue tracing the wire to the valve– or the next break in the wire! ) Also be aware that it takes a bit of practice to use a wire tracer, but it can be mastered in a few hours. The way it works is that you attach a signal generator attached to the valve wire. Then you use a receiver that senses the signal. The receiver beeps when you are near the wire. A word of warning on wire tracers. You need a tracer with a signal generator that is powerful enough for the sensor to be able to pick up the signal through 24″of dirt depth. While most residential irrigation wires are not installed that deep, they are supposed to be! The wire tracers made for use by electricians to find wires in house walls are not powerful enough to detect buried wires, even if they are only a few inches deep. I have one made for detecting wires in walls, that also lists irrigation systems as a suitable use, and it will NOT detect wires buried even 1″ below ground!!! So before you spend money, make sure the device is suitable for wires that are buried underground.

Hey, do you know someone who works as a line-person for a phone or cable company? They may have access to a wire locator since they often use them for repairs. Maybe this weekend they might trade a few minutes of their time for a couple of beers? hmmmm?

Now for the “this is a lot of work” solutions! Start with a trip to the store to stock up on Advil and Ben-Gay.
7. Probing for valve boxes. Before you try digging, first try a shallow probe for valve boxes. If valve boxes were placed over the valves when the system was installed, they are probably just below the surface. Often the only reason you can’t see them is that grass grew over the top of them. A pitch fork is ideal for probing for the boxes, just gently stab the ground until you hear the clunk of a fork tine hitting the plastic box top. If you don’t have a pitch fork a metal yard rake works for some people (others can’t get the motion right to plant the rake tines through the grass), a stick with a long nail-spike on the end of it works good to probe the ground, and last resort is to use a screwdriver on your hands and knees (ouch!) Again, use logic to figure out the best place to start probing.

8. Probe or dig to find the pipes. (My back is hurting just from writing about it.) If no valve boxes were used, then you will need to probe deeper. Now, just to warn you, it is highly likely you will cut or break a pipe or wire while you are doing this. So just be prepared for that as a cost of the process of finding the valve. OK. Fortunately installers who don’t use valve boxes also tend to not bury the pipe and valves very deep, cause they’re lazy and cheap. Normally the pipe from the water supply to the valve is buried deeper than the pipe from the valve to the sprinkler heads. (This pipe is called the “mainline” and is supposed to be at least 18 inches deep!) Plus the wires normally are thrown in the same trench with that mainline pipe going to the valves, and you don’t want to cut or nick a wire with a screwdriver blade. So it’s best to start at a sprinkler head and work backwards toward the valve. Use a long blade screwdriver to gently probe for the pipe around the sprinkler. Try to pick a sprinkler head you think might be close to the valve. If you can turn on the sprinklers, the one closest to the valve will often come on slightly quicker than the others, and have more pressure, so it will have a more “powerful” sound and forceful spray when it is operating. Be gentle when probing, don’t break or pierce the pipe! Once you find the pipe keep probing and follow it back to the valve. If the ground is really dry and hard, you might want to water it to soften it up first. As you follow the pipe consider marking the pipe locations on the grass or dirt using some of that special marking spray paint or the little sprinler flags they sell at irrigation supply stores. Marking the pipe location will help you track where you found pipes (ie; this could be a multi-day project!) Tip; draw yourself a diagram of the sprinkler pipe locations for future use as you find out where the pipes are!

What if you can’t find the pipes with a screwdriver? Well, in that case it’s time for a shovel. Have fun digging up the yard!

Tags: polyethylene pipe, valves, Wire
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Hydro-Zones, Valve Zones, & Sprinkler Pipe Layout

Thursday, January 12th, 2012

Step #4 of the
Landscape Sprinkler System Design Tutorial

Previous Page of Tutorial - - Sprinkler Design Tutorial Index - - Next Page of Tutorial

Hydro-Zones:

The next step in designing your irrigation system is to identify the individual hydro-zones that exist in the area to be irrigated. Different areas of your yard have different water needs. Each of these areas is called a “hydro-zone”. You need to irrigate them separately from one another to keep from drowning some plants while others are dying of thirst. For example, a grass lawn will almost always need more water than a shrub bed. Plants in the shade of a house need less water than those in direct sun. Tropical plants need more water than desert plants. Remember that over-watering plants can be as harmful to them as underwatering. Many plant diseases are the direct result of over-watering, particularly fungus and molds.

Using a pencil lightly outline the different hydro-zones in your yard on your plan. Some hints:

Lawns and shrubs should NEVER be in the same hydro-zone, so start by creating two hydro-zones, lawns and shrubs.
Shady and sunny areas should not be in the same hydro-zone. The shadiest areas are typically in the shadow of buildings where little or no direct sunlight reaches all day long. Go out and walk around your yard. Look for places where the soil stays moist when compared with the rest of the yard. Separate the sunny and shady areas of the lawn area into different hydro-zones. Do the same for the shrubs areas.
Plants with different water requirements should not be in the same hydrozone. Show a separate hydro-zone for any grouping of plants that need more or less water than the others. If you’re not familiar with the water needs of various shrubs look them up in a good garden encyclopedia. You can also tell a lot just by observation. Do some plants in your yard seem to wilt easier than others? On large projects you may also have different soil types in various parts of the irrigated area. These may also need separate hydro-zones. This is very common for golf courses and parks.
Never combine spray heads, rotors, or drip irrigation in the same hydro-zone. The water application rates are different for each of these, which will cause either dry or wet spots. For example, rotors often apply water at half the rate as spray heads. So if you were to combine spray heads and rotors on the same valve, and then turned on the water long enough to apply just the right amount of water in the spray head area, the area with rotors will only get half the water it needs.

The irrigation for each of these hydro-zones will need to be controlled by its own valve. This way the watering times can be individually adjusted for the specific needs of each hydro-zone. Nothing gets over or under watered. Over and under-watering is a major factor in promoting plant disease, and it wastes water. In some small yards it may not be practical to create separate hydro-zones for all the different water needs. This is an individual decision that you will need to make. Another option is to relocate or replace plants that don’t fit in well with others in the area. I often adjust the outlines of lawn areas to avoid small areas I know will have a different hydro-zone than the rest of the lawn, such as in the shade of a building, or under a large tree.

Drip Irrigation Systems:

If you use drip irrigation for your shrubs you can much more easily mix plants with varying water uses together. The best way to do this is to install two separate drip systems in the same area, one irrigating just the high water users and one just the low water users. Another cheaper, but less effective, way is to install more emitters at the plants which need more water. The disadvantage of this second method is that most water loving plants don’t just want more water, they want it more frequently, which is not possible when everything is on the same system. Irrigating too frequently is a major cause of plant disease so be warned!

Valve Zones:

Previously you wrote down your “design flow” on your Design Data Form. As you remember that was the maximum amount of water available for the irrigation system measured in gallons per minute (GPM). Hopefully you also noted on your plan the flow (GPM) for each sprinkler head. Now you need to divide the irrigation system into valve zones that do not exceed that amount of water. Remember that the valve zones can’t cross over the boundaries of the hydro-zones you drew previously. (Hydro-zones can’t overlap valve zones.) Here’s an easy way to do this:

Add together the GPM for all the sprinklers in a hydro-zone.
If the total GPM of all the sprinklers in the hydro-zone exceeds the design flow GPM, you will need to divide the hydro-zone into more than one valve zone.
The total GPM for each valve zone should never exceed the design flow GPM.
Drip irrigation and sprinkler irrigation may NOT be mixed together in a single valve zone. Fixed spray type sprinklers may NOT be mixed with rotor type sprinklers in the same valve zone. You need to create separate valve zones for each of these.

Repeat this procedure for each hydro-zone.

Lightly circle on your plan the heads that are in each valve zone as shown below.

Now identify the location where your valves will be installed. If the valves will be above ground pick somewhere they will be hidden, like behind shrubs. Usually they are placed near the water source but there is no reason they need to be. Remember that if you plan to use anti-siphon type valves they must be installed at an elevation 6″ HIGHER than the highest sprinkler head, so they will probably need to be on the uphill side of the irrigated area. The valves do not need to be grouped together in the same location, you can place them where most convenient. Placing the valves in small groups of 2 or more, close to the areas they will water, can often save money by reducing the amount of pipe needed.

Draw in a valve symbol on your drawing for each valve zone. This will represent the valve that turns on and off the sprinklers in that valve zone. See the illustration on the next page of the tutorial for a typical valve symbol.

Sprinkler Pipe Layout

Now that you have the valve zones shown on your drawing it’s easy to add the pipes going to the sprinklers. Start with one of the valves and draw a line to the closest sprinkler in the corresponding valve zone. Then draw a line to the next sprinkler in the valve zone, and the next, etc. Some helpful tips:

For small residential sprinkler systems try using a different color pencil for the pipes in each valve zone. This will make your plan easier to understand.
Where possible you can minimize the amount of trenching by placing pipes together in the same trench. Show these pipes side-by-side on your plan.
Run the pipes as efficiently as possible. In most cases this will be the shortest possible route between each sprinkler, but this is where you need to just look at your plan and think about it a bit. You may find it easier to run one pipe down the center of an area and spur off of it to each sprinkler. Or it may be easier to split the piping with one pipe going to half the sprinklers and the other going to the other half. Some may want to minimize the number of trenches, even if it means using a less direct route for the pipe so two pipes can share a trench. There is no set routing pattern that you must use for the pipe. If for some odd reason you need to route the pipe all the way around the yard to get to a sprinkler only a few feet away from where you started that’s O.K. Try several different layouts until you find one that YOU like, that fits YOUR needs.

Show no more than 2 pipes connecting to a sprinkler head– one coming into the sprinkler, and one going out. If you need to branch off from the sprinkler with a 3rd pipe, show the 3rd pipe branching off of the 1st pipe just before it goes into the sprinkler. There is no part made that will allow 3 pipes to connect together at a sprinkler head location. Study the sample drawing below for examples.
Try to avoid running pipes within 5 or 6 feet of existing trees. The roots will make it hard to dig trenches for the pipe. With really big trees I try to keep the trenches out from under the canopy of the tree. If I need a sprinkler in that area I run the pipe around the perimeter then go straight in toward the trunk to the sprinkler head. Of course, this may not always be possible. Sometimes you will just have to go through an area with tree roots.

Splitting flows or splitting hairs? You may have heard that the flow from each valve should always be split just after the valve, with one pipe going to half the sprinklers and the other pipe going to the other half. The reasoning is that this “balances” the system. Good designers can balance the flows without resorting to this old method. You are well on your way to becoming a good irrigation designer, so you can forget about such amateurish methods! Route the pipe however you want to route it!

Draw the lateral pipes between the sprinklers and the valves. If you haven’t drawn the mainline pipe from the valves to the water source, draw it now also.

Determine Flows in Pipes:

In order to determine the pipe size we need to know the flow rate (GPM) of the water in the pipe. Calculating the water flow in each section of pipe is extremely easy, but many people have problems with it. They try to make it too complicated. Just observe the layout of the sprinklers and ask yourself which sprinklers are DOWNSTREAM of this pipe section. It’s simple logic, the water must flow through this pipe to reach the sprinklers downstream. Add the total GPM of those sprinklers together and you have the GPM that will be flowing through the pipe.

Start at the valve. The first section of pipe goes from the valve to the first sprinkler head. All the water for every sprinkler operated by this valve must flow through this section of pipe to get from the valve to the sprinklers, right? So the flow in GPM for this section of pipe is the total of the GPM of all the sprinklers operated by the valve added together.
The remaining sections are just as easy. The total flow through each section of pipe is the same as the total GPM of all the sprinklers downstream from that pipe section. Add together the individual GPMs for each of those sprinklers to get the flow through the pipe section. Don’t make it harder than it is! If you have a short spur pipe leading off to a single head, then only the water going to that head will pass through the spur pipe! So the flow for the spur pipe is the same as the GPM of that single head. Carefully study the sample design below.

Using a pencil, write the flow for each pipe section down on your drawing next to the pipe.

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Tags: irrigation design, valves
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Automating a Rain Barrel Irrigation System

Saturday, July 30th, 2011

Q. Can you suggest an affordable electric valve which can be actuated by a standard irrigation controller to control drip systems which are gravity fed from tanks above ground filled with captured rainwater? The water pressure is less than 1 PSI, though flow rate through valve can be as high as 5 GPM.

A.
Automatic Valves for Rain Barrels:
I can’t think of any standard solenoid irrigation valves that would work with a typical rain barrel. The standard solenoid valves used for irrigation systems simply need more pressure than you have available from a typical gravity fed rain barrel. The higher pressure requirement for the valve is a function of the hydraulics that makes the valve operate. You either need more pressure or you need a different type of automatic valve. If you want to create more pressure you need to raise the height of the rain barrel. For every foot you raise the rain barrel you will create 0.433 PSI. The minimum operating pressure of most irrigation valves is at least 15 PSI, that means the barrel needs to be 34 feet above the height of the valve. That is simply not practical in most cases! Now you understand why those water towers you see in some communities are so high!

Yes, they do make motor-operated valves that will work with almost zero water pressure. I’ll address that later.

Use a Pump for your Rain Barrel!
The best way to accomplish what you want may be by not using a valve at all! Consider using a small pump placed on your rain barrel outlet hose. Most irrigation systems do not work very efficiently at the low water pressures typical of rain barrel systems. Thus a pump is often the best solution as it may provide the added benefit of more water pressure.

Drip Emitter Selection
Most people use drip irrigation with their rain barrels, so that is what I will assume here. (If you want to use sprinklers you will probably need a lot more water pressure, and therefore a larger pump.) I’ve found the best emitters for the very low pressures in a rain barrel fed system are the most simple emitters, such as those commonly called a “flag emitter” or “take-apart emitter”. Another popular choice for emitters when using a rain barrel is the adjustable flow emitter/bubbler. These use more water, but are particularly good for watering pots of various sizes as you can adjust the flow needed for each pot. Stay away from higher cost emitters and those labeled as “pressure compensating” as they tend require higher pressures to operate efficiently. Keep the tube lengths short, longer tubes need more water pressure to push the water to the end of the tube. Note: Very low pressure drip systems are going to be less uniform. That’s just the way it is, you will have to either live with that, or use a pump that creates a pressure of 15 PSI (35 feet of lift) or more. Most people just elect to be content with the low uniformity. If you want to test the uniformity of your drip system it is very easy to do, simply build your drip system and attach it to your rain barrel. Then place a disposable plastic cup under each emitter and run the system for a few minutes. All the cups should have about the same amount of water in them. If the water in the cups varies greatly then the uniformity is pretty bad. If the uniformity is bad enough that you think it will create uneven watering you can do a simple test to see if more pressure will help by hooking your drip system up to a garden hose. Be careful, the garden hose will provide more pressure than you need, so turn the valve on slowly and don’t turn it on all the way. Usually the higher pressure from the garden hose will result in more uniformity between the water in the cups.

Selecting and Installing Your Pump
Make sure the pump is rated for enough flow to supply your emitters, and enough lift to get the water needed for your irrigation over the top of the barrel. Add the flow rate of all the emitters together to determine the flow rate needed for the pump. for example if you have 15 emitters that are rated at 1gph (gallon per hour) then the pump will need to supply at least 15 gph. If the barrel is 5 feet tall then the pump will need to lift the water 5 feet. Some pumps list a PSI output value rather than a foot of lift value. To convert PSI to feet of lift multiply PSI times 2.31. So a pump with a 5 PSI output will lift water 11 feet. (5 x 2.31= 11.55)

If you can find one the right size, a submersible pump is the easiest and best method. Unfortunately most are made to be fountain pumps or sump pumps and they don’t create enough water pressure. If you find one that will work for you, attach your irrigation hose to the pump, put the pump in the bottom of the barrel, and run the tube up over the top of the barrel. You will need a air vent at the high point on the tube near the top of the barrel (above the maximum water level) to prevent water from siphoning out of the barrel through the tube when the pump is not running. You can buy an air vent from any drip irrigation store. Or… a very simple and cheap way to create an air vent is to add a drip emitter on the hose at the top of the barrel, so that the water from the emitter drips back into the barrel and is not wasted. When the pump turns off, this emitter will allow air to flow back into the tube and the air will stop the water from siphoning out.

If you don’t use a submersible pump then the pump will be attached to an outlet at the bottom of the rain barrel. Make sure the pump is bolted or screwed down to a firm surface or it will jump all over the place when it runs. The tube from the pump outlet will need to be looped up above the top of the barrel and an air vent (or emitter as described above) installed at the high point to prevent the water from draining out through the pump when the pump is off.

Controlling the Rain Barrel Pump:
The pump can be turned on and off by using a timer. A simple lamp or other household electricity timer will often work for an extreme low cost option, however lamp timers are pretty limited. Most timers of this type will only turn on and off the pump once a day, and do it every day. Most people don’t need to water daily, so this could waste water. If you do use a simple timer make sure it is rated for a voltage and amperage that is equal to or higher than the input of your pump.

If you want to use a standard irrigation timer to control the pump you will need to buy a pump relay unit. Irrigation timers output 24 VAC, most pumps use 120 VAC. So the pump can’t be connected directly to the irrigation timer. A relay is used to allow the pump to be turned on by the timer. You can purchase a pump relay made for irrigation timers at almost any irrigation supply store. Make sure the relay is rated for the correct voltage and amperage for your pump. Instructions for installing and wiring the pump relay should be provided with the pump relay.

Multiple Watering Circuits:
Most rain barrels don’t hold enough water to supply more than a single irrigation watering circuit, but in some cases they might. If you need more than one “valve circuit” you can simply duplicate the pump solution above and use two pumps. Multiple pumps may be the least expensive solution for as many as 3 or more irrigation circuits. As an alternative, you can use multiple motorized valves (see below) with or without a pump. Another alternative is to use a single pump that is sized to provide enough water and pressure for a standard irrigation setup using solenoid valves. I would suggest that the pump for this would need to create a minimum of 25 PSI in addition to sufficient flow to supply the largest irrigation circuit. Use a standard irrigation controller that has a “pump start” feature to turn on and off both the valves and the pump. The pump will require a pump relay to control it as described above for the single pump system.

Motorized rain barrel valves:
They do make mechanical motor-operated ball or butterfly type valves that will open at any pressure. They are used primarily for non-irrigation purposes. Before you purchase a motorized valve I suggest you install your irrigation system and test it using a manual valve as described above. If it works fine without a pump then you can use a motorized valve to control it.

When using a motorized valve make sure the motor operates on 24VAC. When I first wrote this article, the only motorized valves I was familiar with were very expensive, industrial quality models, costing several hundred dollars. However, an email from “Randy G.” says he has successfully used the much less expensive motorized ball valves that are made for hydronic heating systems. I haven’t tested these valves, but I looked over the literature on the Taco valve Randy mentions, and it seems to indicate the valve would work. Per Randy, “the Taco Sentry series are motorized ball valves…, and can be had for $70 or so at most online stores… Honeywell, White-Rodgers, and several other companies also sell ones with similar prices. You can get the Honeywell ones dirt cheap…, but I’ve heard their reliability is lower, so I haven’t tried them – something about oxygen breaking down the rubber over time. And, of course, make sure you get a motorized ball valve, not a heat motor valve, unless you really want to use lots of power and take several minutes to open or close…”

Randy also suggests “Virtually all modern (heating) zone valves are 24VAC, and thus directly compatible with standard irrigation timers, especially the Taco electronic ones that draw relatively little power, good for cheap electronic timers.” To find these motorized valves do a search for “hydronic zone valve”. Be sure to note the connection types for the valves, most are made to connect to PEX pipe or be soldered onto copper. You may have to install adapters to fit them to your irrigation system pipes or tubes.

Special thanks to Randy for supplying this helpful tip! If you try these valves for your system I would love to hear your thoughts on them as well.

People keep writing to say they are having trouble finding equipment that will work with a rain barrel, particularly pumps, so I’ll add some links below as I discover suitable products. Disclosure: I get a small commission on sales of these items if you buy them through these links.

The Little Giant 35-OM pump is made for high pressure applications like commercial carpet cleaners, but it produces good pressure at a low flow, a combination that is great for small drip systems. Amazon doesn’t list the performance chart for this pump so here it is:

40 gph at 70 ft hd
60 gph at 65 ft hd
80 gph at 58 ft hd
100 gph at 54 ft hd
120 gph at 45 ft hd
140 gph at 30 ft hd

gph = gallons per hour. gph/60=gpm
ft hd = feet of lift. ft hd x 0.433 = psi (pounds per square inch)

Tags: gravity flow, irrigation design, pumps, rain barrel, valves
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How to Use Pressure and Flow Switches with Irrigation Controls

Thursday, May 26th, 2011

Almost any major maintenance problem in an irrigation system will cause a unusual pressure level or flow level in your irrigation system. Therefore pressure and/or flow monitoring is a good way to detect problems. Most of the time the response to a abnormal pressure or flow level would be to shut down the system, or possibly to shut down the current valve zone and try another one. Irrigation systems are typically shut down using what is called a master valve. A master valve is a single valve located at the water source that can shut off all the flow of water into the irrigation system. For more details see my article on master valves. On systems with a pump you will probably want to shut off the pump. Sometimes, as with booster pumps, you will need to both shut down the pump and close a master valve.

So what problems might an abnormal pressure or flow indicate? A very low pressure may indicate that perhaps the pump is broken (if you have a pump), an intake screen is clogged, a filter is dirty, a valve failed to open, or a pipe has broken. Abnormally high pressure could be the result of a valve not opening when it should, a dirty filter (if the pressure is measured upstream of the filter rather than downstream) or some obstruction in the pipes. Low flow could indicate a valve failed to open, a filter is dirty, or that a pump isn’t working as it should. High flow could indicate a broken pipe, a broken sprinkler, or a valve that is stuck open. In most cases monitoring either flow or pressure is sufficient as opposed to monitoring both.

How to Monitor Your Irrigation System

There are a number of different ways to detect and respond to abnormal pressure or flows. Following are a few or these. If you would like to suggest other methods, please contact me. I realize this is not an exhaustive list.

Use a Smart Irrigation Controller that has a Sensor Input and Response Feature:
This is probably the easiest way to add pressure detection and response. It is also what I consider to be the preferred method, as it is reliable and gives you the most control. Some high-end irrigation controllers can use an electronic sensor hooked up to the mainline pipe to monitor the water in the irrigation system. Some of these controllers use flow sensors, some use pressure sensors, some can use both types. These controllers with advanced features are typically sold as Smart Controllers and are expensive compared to ones typically found on a residential irrigation system. Prices for these controllers typically start around $300.00 and go up into the thousands for ones that handle dozens of stations. But then you get a lot more with them too. They are sold through professional irrigation supply stores, both online and locally.

WARNING: Be sure the controller will do exactly what you want BEFORE you purchase it! Not all controllers marketed as “Smart Controllers” have these sensor input features, many only work with specific types or even models of sensors, and some controllers may not provide the response options you want or need. You need to research the controller carefully. Don’t rely on a simple check list of features! “Sensor input” can mean almost anything, you need details! I have seen controller feature lists where the unit sounded fantastic and ultra flexible, only to discover after closer examination that the actual response features don’t do what I need or want. Read the actual owner’s manual (most controller manufacturer’s have them available on their websites) to see what the true capability of the controller is. Read the sections of the manual on how to hook up the sensor, then there will also be a separate section on how to program the sensor you should look through. Some controllers allow for time delayed responses, some don’t. If you have a pump you will almost always need a time delay feature to bypass the sensor when the pump is starting up. Even those controllers that do allow you to add delay times may not allow as much or little time as you need. It is critical that you do as much research as possible before you go to the expense and effort of purchasing, installing and programming the controller.

For example, I have a Rainmaster Eagle Smart Controller on my own irrigation system, as well as using it on the majority of the commercial systems I design. This particular Smart Controller has flow sensing capabilities, but it does not have built-in pressure sensing capability. It does have a delayed response allowing delays of 1-6 minutes, but only in one minute intervals. It will also allow the use of one additional simple on/off type sensor (most controllers have a circuit for this type of very simple sensors. A simple rain switch is an example of this type of sensor.) It has an audible “chirp” alarm that alerts you that a sensor response has been activated. While this particular controller meets my needs, it certainly will not meet everyone’s. Almost every major irrigation company makes a Smart Controller, and each has different features and capabilities. Be sure you are using up-to-date resources when checking out models. Smart Controller models are introduced each year, and often the capabilities of existing models change from year to year, so it is hard to keep up with them.

When using a controller with a pressure and/or flow sensor you start by installing the actual sensor on the mainline pipe. The method varies with the brand and model of sensor, most are pretty easily installed. The sensor is wired to a special terminal on the irrigation controller. Typically the wire used must be a special shielded communications cable, rather than standard irrigation valve wire. Consider installing communications cable in PVC conduit to protect it, as it is very sensitive to even the smallest nicks from shovels, animals digging it up, or rodents chewing on it. Most pressure sensors work by sending a reading of the current pressure to the controller every few seconds. A typical flow sensor has a small paddle that turns as the water flows through the pipe. Flow sensors normally send a signal based on the amount of flow, for example they might send a signal each time 5 gallons of water has flowed past the sensor. The controller then interprets that data from the sensor and responds. In most cases you will pre-decide what the response will be when you set up the controller. For example; if you have a system with a pump, you could program the controller to shut down the irrigation system if the pressure was below 10 PSI for more then 2 minutes during the set irrigation period. The 2 minute qualifier (delay) for shut down would allow the pump time to pressurize the system during start up and also avoid “false alarms” caused by brief dips in pressure.

Using a Simple Pressure Switch with a Pump Operated System:
This method is for those with pumps. What I am describing here is for emergency shut off only. I’m assuming you already have something set up to turn on or off the pump during normal irrigation operation. That might be a standard pressure tank with a pressure switch to control it. Or you may be using the pump start feature on the irrigation controller to actually start and stop the pump using a 120v relay. The new pressure switch we are talking installing in this case is used only to detect pressures that indicate a problem and turn off the pump. So if all is hooked up properly, in the event of blockage or no water going into the irrigation system the pressure will drop and the new pressure switch will shut the pump off.

This method requires that your irrigation system is leak free and can hold pressure for days between irrigations. If the system is not leak free see #4 below.

1. Make sure you have a really good quality spring-loaded check valve on the irrigation mainline pipe. The check valve goes someplace after the pump, but before the pressure switch. A good quality check valve is needed to keep the water from leaking backwards out of the system through the pump. Typically the self-priming feature of the pump is not good enough by itself to do this, you need a separate check valve.

2. You will need to use a pressure switch that works backwards from normal ones used for household water systems, since you want the switch to shut off the pump at low pressure (standard switches used on household water systems turn on the pump at low pressure.) Some switches can be wired to work either way, others can’t. Keep in mind that the low end on many common pressure switches in around 25-30 PSI. That might be a bit higher than you want for a low end shut off, especially if your system will be operating at less than 45 PSI. You don’t want accidental “false” shut offs since the only way to get the system back on will be to manually start the pump and hold it on until the pressure is back above the shut-off level.

3. There a problem to be dealt with. The problem is that valves close slowly, taking as much as a minute or two to close after the controller tells them to. At the end of the last irrigation cycle a typical controller closes the last valve and immediately shuts off the pump. But it takes the valve several seconds up to a minute or two to actually close. During this closing period the system will depressurize. With no pressure in the system the pump will not restart for the next irrigation cycle, because the low pressure shut-off switch is detecting low pressure and shutting off the power to the pump. There are two ways to deal with this.

A. You can fool the controller into keeping the pump running after the last valve circuit has finished watering. Your controller needs to have the capacity for one extra valve on it to do this, so if you have 10 valves you will need a controller with 11 stations. The last station on your controller needs to not have a valve attached to it. Program 1 minute of time on that last station. Now the controller thinks it is operating one last valve, so it keeps the pump running. That will keep the system pressurized while the final valve closes. If one minute is not enough time for the final valve to close then add another minute of run time to that last empty station.

B. Some controllers have a built in delay feature that keeps the pump running after the last valve closes. This feature keeps the pump start circuit energized, which keeps the pump running for a minute or two after the last valve is signaled to close. This gives the valve time to close before the pump is shut off. Some less expensive controllers have this feature. But typically only high-end controllers have this feature, so this method isn’t very practical. If you are going to buy an expensive controller you might as well forget about using a pressure switch and use a Smart Controller and a sensor to shut the system down, as described in the first section of this article.

4. Often a small leak will cause the system to depressurize between irrigation runs. This can be a major problem. The pump will not start if the pressure is low, the low pressure switch is going to shut off the power to it.

If the leak is very small you can install a pressure tank, just like on a typical house water system. Assuming a small leak, the tank keeps the system pressurized. But that only works with a very small leak and it can take a huge pressure tank to supply enough water to keep the system pressurized. If your system has a larger leak you will need to find and repair the leak. If you can’t get the system leak free, you will need to take a different approach, as described below.

You can use a timer to over-ride the low pressure switch, and allow the system to start even with no pressure. You will need a “Time Delay Relay”. The time delay relay needs to be the type that allows the power to flow when energized, then shuts it off after a minute or two of delay. It needs to have an automatic reset. You then install the relay on a bypass wire around the low pressure switch. That way the pump can start even when the pressure switch is “off” due to low pressure. You will need to work with someone knowledgeable when ordering the time delay relay to be sure you get the correct relay, as they make many different kinds.

Using a Pump Controller with a Sensor:
This is essentially the same method as the Smart Controller method I described earlier. Only the “smarts” are in the pump controller rather than in the irrigation controller. Some of the newer digital pump controllers (don’t get confused here, we’re talking about a separate pump controller, not the sprinkler controller) are programmable, they are simply a small computer that operates a relay that starts and stops the pump. You hook them up to a pressure sensor, also to the irrigation controller, and to any other sensor you want (wind, rain, temperature, light, flow, you name it.) Then you can program them to do just about anything using that information input. They can turn off the pump if a low pressure occurs for more than x number of seconds, turn off the pump if a high pressure occurs for x number of seconds, turn on the pump at a given time of day, etc. Pretty much any input you want can cause the pump to turn on or off. The capability depends on the brand and model of the pump controller. The downside is it takes electronics know-how to set the thing up and someone tech savvy to program it. Typically you hook up a laptop to the pump controller to program in the logic, then once it is programmed it runs by itself. The laptop just gives you an interface that is easier to work with. I really can’t give you much more details beyond that, this type of pump control is beyond my expertise, I just have seen pump system experts use them to do amazing things.

Tags: flow sensor, flow switch, irrigation design, master valve, pipe, pressure sensor, pressure switch, pumps, valves
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All Valves Come on and Stay On Continuously

Friday, May 6th, 2011

Q. I just restarted my sprinkler system after it had been winterized. When I turned on the water to the system, all the valves stations came on at once, as if by-passing the timer unit. Even when I turn the timer unit Off, the sprinklers keep running.

A. This is a common problem when restarting after your sprinkler system has been winterized, or after the system has been turned off for an extended period of time. It also often occurs with brand new solenoid valves that have just been installed. There are a couple of possible problems that can cause this, so we’ll look at a couple of solutions. One of the tricks below should get your irrigation valves opening and closing properly again.

Air Trapped in the Valve:

The valves may have air trapped in them. A small bubble of air becomes trapped in the tiny water ports of the valve, this stops the water from flowing through the port. Since the water flowing through the port is what holds the valve diaphragm closed, the valve stays open.

1. Turn on the main water supply.

2. Now go to the individual valves and using the manual open & close control on the valve. The manual open & close control is either a lever on the valve (most often it is under the valve’s solenoid), or it may be a screw on the top of the valve bonnet. If it is a screw don’t fully remove it, just open it until water starts squirting out. Set it to open, wait a few seconds, then set back to closed. If the valve doesn’t close within a minute, try it again. It may take several tries to get the air bubble to “burp” itself out. Try tapping the valve to dislodge the air while the valve is open if needed. Note: old plastic valves may become brittle and crack when tapped, so if the valve is plastic and old don’t tap on it except as a last resort if the air doesn’t come out.

3. If that doesn’t fix the problem, you can almost always force the air out using the manual flow control on the valves. Unfortunately, some inexpensive valves do not have a flow control. The flow control is a handle, similar to what a manual valve has, that is on the top of the valve. It works just like a regular faucet, turn clockwise to close. Most flow controls have a hand operated flow control, others have a cross handle that is turned using a tool (pliers will work if you don’t have the special valve opening tool.) A few valves have a screw for the flow control that requires a screwdriver to turn. Try completely closing and then reopening the manual flow control on each valve. That should force the air out and fix the problem.

Valve Needs to be Throttled:

If air in the valve doesn’t seem to be the problem it is possible that your valves don’t have enough pressure differential and they need to be throttled in order for them to close by themselves.

Here’s how to throttle them using the flow control adjustment:

Note: some inexpensive valves do not have a flow control adjustment feature on them. If that is the case you are not going to be able to do this. You will need to replace the valve with a better quality valve that has a flow control.

1. Use the manual flow control on each valve to close all of the valves. Now the main water supply should be on, but none of the valves should be allowing water through. So no sprinklers are running.
2. Start with just one valve at a time. Rotate the manual on/off lever to the on position. Open the manual flow control knob all the way (turn as far as it will go counterclockwise). The valve should come on and sprinklers run.
3. Next rotate the manual on/off lever under the solenoid to the closed position. The valve should close (it may take it a minute or two to close) but probably won’t, because that is the problem, they won’t close! If the sprinklers turn off the valve is working correctly, go to the next valve and start again with step #2. If the valve does not close by itself, you need to throttle the valve. Continue to step #4.
4. To throttle the valve you partially close the flow control knob. Start by turning it one full turn clockwise. Wait a minute for the valve to close. If it doesn’t close, turn the handle another half turn clockwise. Wait again. If the valve still doesn’t close turn it another half turn. Keep doing this, at some point the valve should suddenly make a whooshing noise and close. If the valve is broken it will never close by itself and eventually as you close the flow control more and more the sprinkler radius will start becoming noticeably reduced. If that happens you need to repair or replace the valve. But in most cases the valve will close by itself after you have partially closed the flow control. It might take 4-5 complete turns before this happens.

You shouldn’t see any significant change in the sprinkler performance with the valve flow control in the partially closed position, except that the sprinklers may mist a little less (which is a good thing.) This is called “throttling the valve” and some valves won’t close by themselves unless they are throttled. The way a solenoid valve works is that the pressure differential as the water goes through the valve is what the valve uses to power itself into the closed position. If there isn’t enough pressure differential the valve will not close by itself. Often there is not enough pressure differential when there aren’t very many sprinklers on the valve circuit. When you throttle the flow control you are simply increasing the pressure diferential.

You can leave the flow control in a partially closed position permanently, it will not hurt the valve. The valve is designed to allow you to do this. The sprinklers should still operate well as the amount of water throttled when you partially close the valve is not significant.

For valve repair instructions see how to fix a solenoid irrigation valve.

Tags: repairs, Sprinklers, valves, winterization
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Valves Downstream from Anti-siphon Valve?

Saturday, April 30th, 2011

Q. I have manual shut-off valves installed downstream from my electronic anti-siphon valves. I installed them to turn off the water to parts of my yard where I grow annuals and only need to water for a few months out of the year. I would really appreciate it if you would explain why valves downstream cause the anti-siphon valve backflow prevention to fail.

A. If there are some sprinklers that are not shut off by the downstream valves (ie; there is always a sprinkler that will be on when the anti-siphon valve is on) then you should be fine. The key to this is that when the anti-siphon valve is closed the water remaining in the pipe downstream of the anti-siphon valve MUST become depressurized. Depressurizing normally occurs when you shut off the anti-siphon valve and the remaining water pressure in the downstream pipes is released through a sprinkler. But if you have a valve downstream of the anti-siphon valve it will trap pressurized water in the pipe between the anti-siphon valve and the downstream valve and not allow it to “depressurize”. Note that sprinkler heads with built-in check valves will also hold the water pressure in the pipe. That is why when using anti-siphon valves you should remove the check valve from at least one of the sprinklers on each valve circuit (normally you would remove it from the sprinkler on the circuit with the highest elevation.) the check valves are easy to remove from the sprinklers, normally you just unscrew the sprinkler cap and lift out the riser assembly. You will see a rubber washer attached to the bottom of the riser assembly, pull it off. That rubber washer is the check valve seal, with it removed the check valve won’t work. Now reassemble the sprinkler.

How an anti-siphon valve works:
The anti-siphon valve works by use of a little air vent that is located on the downstream side of the actual valve. Look at the anti-siphon valve you will see there is a large cap directly above the water outlet of the valve, the air vent is under this cap. If you look closely at the lower perimeter of the cap you will see holes or slits that allow the air to move in and out of the vent. When the anti-siphon valve is turned off the pressure drops in the pipes downstream from it as the remaining water flows out of the sprinklers. When the pressure drops the little air vent drops open and lets air into the pipe right behind the valve. This air goes into the pipe and breaks any siphon effect (“anti-siphon”) so that sprinkler water can’t be drawn backward through the valve into the potable water supply.

(Water from the sprinkler pipes can be siphoned back into the water supply system when pressure is lost in the water supply system. For example, the water company might depressurize their pipes to make repairs. It doesn’t happen frequently, but it does happen. When the pressure drops the flow reverses and water from the sprinkler pipes, along with dirt and other yucky stuff, can be sucked in through the sprinklers and then into the water supply system. When the pressure returns that dirty sprinkler water may go back into the sprinkler system, but it may just as easily go to your kitchen or bathroom sink. So why wouldn’t the closed anti-siphon valve stop this from happening? After all the purpose of a valve is to stop water from flowing through it when it is closed, right? Yes, of course, if the valve is a manual valve. But electric solenoid valves are “directional” valves. What that means is they are designed to stop the flow when the water is flowing in one direction only. When the water flows backwards they don’t fully close!)

What the downstream valve does:
If you have another shut-off valve after the anti-siphon valve, then the water on the downstream side of the anti-siphon valve will stay pressurized even when the anti-siphon valve is closed. This water pressure holds the little air vent in the closed position so it can’t let in air, and therefore the siphon effect is not broken. This means the anti-siphon part of the valve will not work. Even worse, when the little vent is held closed for days at a time due to the constant downstream pressure, it eventually just sticks in the closed position. Then even if the pressure drops the anti-siphon won’t work.

My Friend or Irrigation Person Says This is All Just Something YOU Made Up!
Unfortunately, this wrong practice of installing valves after an anti-siphon valve is pretty common in the irrigation industry. I’ve been called some pretty ugly names over this issue. Fortunately for me, you don’t have to take my word for it. Tell your friend/buddy/pal to read the box the anti-siphon valve came in. It says right on it “do not install valves downstream” or something similar. If you don’t have the box or it didn’t come in one, then go to the manufacturer’s website and find the anti-siphon valve installation instructions. You will find that same warning. Here’s a sample from Rainbird if you want to check for yourself: Rainbird Anti-siphon Valve Operation Manual. See the section that starts with the heading “CAUTION”.

Tags: anti-siphon valve, backflow, hydraulics, irrigation design, valves
Posted in Questions and Answers | No Comments »

Can I Run Two Irrigation Valves at the Same Time?

Tuesday, March 29th, 2011

Q. Is it possible to have two valves on at the same time or to run two irrigation valves at once?

A. Yes, it is often possible to run two valves at once. However there are several problems that can occur.

You must have a sufficient water supply for both valves to run at once. If the performance of the sprinklers suffers and you start seeing dry spots in the landscape, you obviously don’t have enough water. You may need to do some adjusting of the sprinklers as the water pressure operating them is likely to be less when two valves are on.

Both valves running at the same time may require more water than the pipe supplying them can reasonably handle. This can result in water hammer, or premature pipe wear/failure, due to high water velocity.

Water Hammer: Listen for a loud water hammer “thump” or “bang” noise when the valves close. A gentle thump is fine, but if the pipes reverberate from it that is not good. Run just one valve and listen to the sound when it closes. Assuming the irrigation is properly designed, that should be the “normal” closing sound. Now listen to the sound when both valves are closed together to see if it is significantly louder. If it is significantly louder, that is not good. You can possibly reduce or eliminate the water hammer problem by closing the valves separately, one at a time.

High Velocity: Premature wear due to velocity is harder to figure out. It generally isn’t a problem unless the water is really flowing fast through the pipe, like 8 feet per second or higher. The only way to determine if it is a problem is to do a couple of calculations. Start with the sprinklers. On top of each sprinkler is an identifying names and part numbers that tell you the brand, model, and hopefully the nozzle size. Write down that information for each sprinkler, then look up the water use (GPM value) for that sprinkler and nozzle at the sprinkler company’s website. (You may need to call the company’s help line to assist you, each brand and model is different so I can’t give exact instructions.) Now add together the GPM values for all the sprinklers that are running at the same time when two valves are turned on. This will tell you how much water the two valves require when running together. Next find the size and type of the water pipe that leads to the valves. (For example it might be a 3/4″ copper tube, or maybe a 1″ PVC pipe. It may be several different sizes and types of pipe, in which case you would use the smallest pipe size and type.) Using that information you can calculate the velocity of the flow in the pipe using the Friction Loss Calculator at http://www.irrigationtutorials.com/formulas.htm#sec8. Just enter the pipe type, size, and GPM into the calculator and it will give you the velocity.

If you decide to use a controller to operate the valves the controller must be a brand that provides sufficient amperage to run two valves at the same time (most do.) If you want the controller to run the valves at the same time, but start and stop them about one minute apart to reduce water hammer, you will need a controller that allows you to run two separate valve zones at the same time. Most controllers have a “stacking feature” that prevents them from doing this. You will need a controller that allows you to turn off the stacking feature. Most controllers can’t do this. You will probably need to enlist a knowledgeable controller salesman at a professional irrigation supply store to assist you in finding a controller that will work for this unique situation.

Tags: GPM, hydraulics, irrigation design, PSI, valves
Posted in Questions and Answers | No Comments »

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