BASIC IRRIGATION DESIGN AND TROUBLE SHOOTING TIPS

Transcription

1 BASIC IRRIGATION DESIGN AND TROUBLE SHOOTING TIPS PRESENTED BY NORTHWESTERN SUPPLY, INC SANDIFER BLVD. SENECA, SC PHONE FAX

2 Site Information Measure the outline of the property to be irrigated. Find location of meter and where you want the controller. Make sure to include all obstructions in position on the property. (Drive-ways, sidewalks, pools, underground wires, etc.) Determine size of service line and where you are going to tie into the line. Also, determine size of main water line to be used for irrigation. You need to know the working pressure. You can do this by using a pressure gauge on the hose faucet, while opening another hose faucet or turn on water at another location. If you want to test the pressure yourself, everything that uses water in your home: faucets, ice makers, etc., must be turned off when you take the measurement (that's why its called "static" water pressure, the water isn't moving). This is critical or you will get a false low reading! You can test the pressure at any faucet. If all the water is turned off, the pressure will be exactly the same regardless of where you test it. Check with local utility companies for the location of any buried lines on site. Placement of Irrigation Heads There are three types of sprinklers: sprays, rotors and drip (low volume sprinklers). Head to head spacing or 50% (diameter) sprinkler spacing is the most common spacing used in landscape irrigation. If there is an area that has high wind conditions, heads should be spaced 40 to 45% of diameter. Sprays are used in shrub areas and in small turf areas where rotors would be throwing water to far. Sprays can be mounted on a fixed riser or on a pop-up body which is below ground when the system is not in use. Rotors are used for turf areas that are greater than 18 feet in radius. Drip is used for areas that require less water. (Shrubs, flowers, ground cover). Spray and rotor placement is started on the outside edge of the area to be irrigated and then fill in the middle if necessary. It is very important that you do not mix sprays, rotors or drip irrigation on the same zone together. Each type of sprinkler releases water at different rates. Mixing different types of heads will give you wet spots, dry spots, mold and bugs. Try to keep all sprinklers at the same gpm of the other sprinklers in that zone. This will distribute water evenly.

3 Zoning the System Decide where you are going to tie into the existing water service line. It is usually best to tie into the water service line closest to the meter. The reason being, you are then closest to the city main, and your water is traveling through fewer obstructions to get to your sprinkler system. Generally a residential meter will be 5/8 or 3/4 which you can safely plan on using 1 pipe as your main line and for your lateral lines. Do not exceed the 18GPM flow in 1 PVC pipe. Exceeding the GPM will cause problems, like low pressure and desired amount of heads on a zone. Calculations of loss of pressure through pipe will also need to be accounted for. (Chart included in following pages) Install backflow device on main irrigation line, immediately after tying into main water service line. To zone your heads (group the ones together that will be running at the same time) you need to know how many GPM is available for your use. Count the GPM as you go and when you reach the total of GPM calculated for your size pipe then stop and start on a new zone. If possible start zone from middle to distribute water evenly. If you are installing a pump for your irrigation system, your pipe size will need to be calculated differently. The size of pipe will be determined by elevation and length of irrigation line. We can help determine these factors. Come in and see us for help in designing your pump application. Assigning where you want your valves to go is determined by whether you want them all together in one location or spaced about the yard where the zones actually are. If valves are located outside of house, always use a valve box over them to protect them and provide easy access, when service is necessary. Valves should be located where they will not interfere with normal traffic or use of area. Normally, a valve should be the same size as the lateral line it serves. Always use waterproof splices on your valves. Controller choice is done by how many zones you will need to finish your irrigation system. There is a variety of controllers that can be used. Check with us on which controller will best suit your irrigation system. The easiest way to install the pipe is to start at the water source and work out to the valves, and then continue to the end of each lateral. Assemble the pipe outside of the trench and then lower the assembled sections into the trench as you move along. Try to avoid getting dirt into the pipe as you assemble it. After installing your main and lateral lines for your irrigation, and before installing your valves, flush your lines thoroughly. Open the backflow valve to full open position and let the water run for at least 5 minutes. This will eliminate any PVC shavings from pipe or dirt from entering

4 electric valves. After installing electric valves, and before installing sprinklers, flush lines again. This will protect any debris from clogging the heads. The worst enemy of your new irrigation system is plain old sand. It will get into your sprinkler nozzles, valves, or drip emitters. Proper flushing of the irrigation system is one of the most important steps you will take. You can also lay your lateral line in the same trench as your main line to reduce labor. Another helpful idea would be to lay your irrigation wire in the same trench with the PVC pipe, taping the wire to the pipe every 5 to 10. This will protect your wire and be helpful for service in the future. Precipitation Rates Rotors typically throw 40 at 45 to 50 psi and distribute 2.5 gpm. Variable arc nozzles for spray heads vary, according to size and pattern. (Charts in following pages.) Precipitation rate is simply inches of water per hour that is placed over a certain area. If the sprinkler heads in a front yard deliver 1 inch of water over the entire front yard after running for 1 hour, then we can say the precipitation rate of the sprinkler heads is 1 inch per hour x gpm ftx2= inches per hour Plant Water Demand Plant Type lawn grasses ground covers shrubs trees roses perennials & annuals vegetables Water Demand 1 1/2 2 per week 1/2 1 per week 1-1 ½ per week 1 1 ½ per week 2 per week 1 1/2 2 per week 2 per week plus

5 Winterization In a freezing climate it is advisable to winterize the irrigation system in order to avoid damage to your system. You should remove as much water as possible from the pipes, valves and sprinklers. You can do this in several different ways. You can install a drain valve at the lowest point of each zone. You can install auto drain valves that drain every time your zone shuts down. Or you can install a manual valve at the lowest points. You can also blow out the lines with air. Manual Drain Method Use when manual valves are located at the end and low points of the irrigation piping. To drain, shut off the irrigation water supply, open all manual drain valves. Open the test cocks on the backflow device. If your sprinklers have check valves you ll need to pull up on the sprinklers to allow the water to drain out the bottom of sprinkler body. Depending on the location of the drain valves, there could be some water left in the backflow, the piping and the sprinklers. When all or most of the water has drained out, close all the manual drain valves. Blow Out Method The blow out method needs an air compressor. The compressor is attached to the mainline, after the backflow device. Compressed air should not be blown through any backflow device. Shut off the irrigation water supply and activate the controller that is the zone or sprinklers highest in elevation and the furthest from the compressor. Close the backflow device. Then slowly open the valve on the compressor, this should gradually introduce air into the irrigation system. The blow out pressure should remain below the maximum operating pressure specification of the lowest pressure rated component on that zone and should never exceed 80psi. Each station/zone should be activated starting from the furthest station/zone from the compressor slowly working your way to the closest station/zone to the compressor. Each station/zone should be activated until no water can be seen exiting the heads, this should take approximately two minutes per station/zone. It is better to use two or three short cycles per station/zone than to have one long cycle. When winterizing a pump it is best to read the manufacturers instructions on winterization. Manufactures warranty does not apply to freeze damage. Drain pump when disconnecting from service or when it might freeze. Normally a ½ drain plug is located on the bottom side of the pump. Controller should be turned to an off position and mv/pump and common wires should be disconnected from controller. Rain Sensors Rain sensor types with a cup or bowl that catches water, you might want to remove the water and place a plastic bag over the sensor. This will keep any water from accumulating and freezing in the cup or bowl area. If your sensor is the type that uses wafers or discs, you might want to remove the wafers and store them in the garage for the winter months.

6 Spring Start Up Procedures Make sure any manual drive valves are closed. When you first turn on your sprinkler or drip system in spring you should always flush it out. During the winter many small critters take up residence in your sprinklers, emitters, tubes, and pipes. To do that open the ends of drip tubes and flush them out by turning on the water. For sprinklers remove the nozzles from, at the least, the last head on each pipe (better yet, remove them all) and run the water. After flushing, check the system out by running it. Look for clogged emitters or nozzles. Check for leaking valves. Often the valves diaphragm will dry out over the winter. Test each zone valve by manually activating it from the controller. Walk through each station on the controller, checking for proper operation of the zone. Check for proper rotation and adjustment of sprinkler heads and adequate coverage. Check and clean filters on poorly performing sprinklers. Reprogram the controller if needed. Replace the controller back-up battery if necessary. Uncover and clean the rain sensor, if one is installed. Clean out any inline filters.

7 GPM for S40 S40 Pipe Size Gallons Per Minute 1/2 7 GPM 3/4 11GPM 1 18 GPM 1 1/4 32 GPM 1 1/2 44 GPM 2 70 GPM 2 1/2 100 GPM GPM Maximum One way Distance in feet Between Controller and Valve Common Wire Size Control Wire Size

8 Valve Trouble Shooting Valve troubleshooting starts with a few basic questions: Is the irrigation controller plugged in and properly programmed? Is the master water supply turned on? Is water present to the valve? Is the flow-control handle open? Is sufficient water pressure and flow available? Is the pump working? Before troubleshooting begins, you must understand how irrigation valves work. Valves control the flow of water to sprinklers. A valve stays closed because the surface area above the diaphragm is about two-and-half times larger than the pressurized surface area below the diaphragm. The difference causes a greater force above the diaphragm than below it. The valve traps the water, which fills the upper chamber. The valve will open only when the force above the diaphragm has been relieved. This will happen electrically when the controller energizes the solenoid or manually when you use the manual bleed. The solenoid is a coil of electrical wire that, when charged with an electrical current from the controller, creates a magnetic force and pulls up a small, metal plunger inside the valve. As the plunger rises, it dumps water from the chamber above the diaphragm to a lower (downstream) pressure area. This reduces the force above the diaphragm and the valve opens. To close a valve, the irrigation controller stops sending an electrical current to the solenoid. As the current terminates, the solenoid drops the plunger and stops the flow of water from above the diaphragm. The pressure above the diaphragm builds to a force greater than the pressure below the diaphragm, and the valve closes. This also occurs when you operate the valve manually. When you open the manual bleed screw or manual lever, you relieve the force above the diaphragm either to the atmosphere or to the downstream side of the valve. A variety of conditions can cause an irrigation valve to malfunction. But don't overlook the obvious. If the valve will not open, make sure you have turned on the water supply. You can check to make sure you have a water supply by manually opening or "bleeding" the valve. If there is still no water flow to the valve, check the PVC line for breaks. Another common problem is lack of voltage to the valve. To determine if the valve is receiving power, use a volt-ohm meter. From the irrigation controller, manually turn on the station you are troubleshooting. With the volt-ohm meter, check the voltage between the ground and the controller-station terminal. Your reading should be 24 volts AC (VAC). While you are at the controller, check the entire irrigation program. In many cases, a valve will not operate properly because of faulty controller programming. If your meter reads 24 VAC at the controller station wires, check the zone in question to make sure it's operating. Make sure that the controller has a programmed start time and run time and that the "days-to-run" setting is programmed.

9 If the controller is working properly, check the voltage to the solenoid. With the controller turned off, skin the insulation off the two wires running from the valve solenoid to the splice. Make these cuts as close to the splice as possible. Attach a voltmeter to the wire running from the splice, the voltage should read zero. Manually operate the irrigation controller, and check that you are receiving 24 VAC. It is normal to experience some voltage loss at the valve, but if the volt-ohm meter reads less than 20 VAC, the field wires have a problem. You need to find the source of this problem or replace the wires. Because of its direct connection to piping from the main water line, a valve is susceptible to contamination from dirt and debris, especially if you use non-potable or effluent water. To reduce the risk of contamination, most irrigation valves have a filter or screen to keep dirt out of the area above the diaphragm and the solenoid area. Dirt and debris trapped in the valve may cause it to "weep." The telltale sign of a weeping valve is excessive puddling at the lowest sprinkler after the valves have shut off. To check for excessive dirt, debris or algae buildup, turn the water off, remove the valve bonnet, and look for dirt or debris. This is also a good time to check the diaphragm and valve seat for debris, wear or deterioration. The diaphragm, which is a large, rubber-like, flexible disc, is subject to deterioration. It can be nicked or torn by a trapped pebble or a build-up of grit. The valve seat is the lower sealing surface in the valve body. Inspect it for nicks by running your finger over the lip of the valve seat. Replace the valve body if the valve seat is damaged. Solenoids, If you have checked the water supply, the power supply and the diaphragm and valve seat, and the valve is still malfunctioning, usually the only possibility left is a faulty solenoid. With the water turned off, unscrew the solenoid from the bonnet of the valve. Be careful not to lose the plunger or the small spring, which helps force the solenoid plunger downward. Inspect the solenoid plunger. The plunger is the small, metal piston with a rubber base inside the solenoid housing. The plunger must be clean and free of any debris. To check the operation of the solenoid, manually turn on the valve or zone from the irrigation controller. If it's working, the solenoid plunger will be pulled into the solenoid body. Some irrigation-equipment manufacturers have designed "captive" solenoid plungers. A small piece of plastic holds these types of plungers in the solenoid housing. If the valve has a captured solenoid, you will hear a sharp clicking sound when the solenoid energizes. If the solenoid is not working properly or if the solenoid plunger does not move freely in the solenoid housing, clean and retest it. If it is still not working, replace the solenoid. Also, with the solenoid removed, check the small hole in the bonnet that allows water to pass from above the diaphragm to the downstream side of the valve. Check the opening with a paper clip or small piece of wire. It is important not to enlarge this hole because it controls the opening and closing speed of the valve.

10 Troubleshooting Field Problems That Cause Low Pressure 1. Moderate to large mainline or lateral line leak. 2. Another zone valve stuck on at same time.. 3. Slow closing valves. 4. Incorrect nozzle sizing. 5. To small of pipe size. 6. To many heads on a zone 7. Do not have enough pressure from the start. 8. Check flow control on valve. 9. Clogging of dirt, algae or debris. 10. Cracked or broken fitting in bottom of head. Field Problems When There is No Flow 1. Zone valve not opening 2. Water is shut off (either at meter, manual valve or backflow. 3. Irrigation controller programmed incorrectly. 4. Valve problem, such as failed solenoid coil, diaphragm ripped, clogged port (with sand, rocks, pvc shavings etc.). 5. Valve turned off manually. 6. Irrigation control wire cut, bad wire splice, valve solenoid not connected to wire. 7. Rain sensor is on. Some Gear Driven Sprinkler Heads Not Rotating or Popping Up 1. Trash clogging bottom of sprinkler. 2. Grass or grit on shaft of sprinkler. 3. A leak in barb fitting or funny pipe. 4. Low pressure on zone. 5. Too many sprinklers on one zone or exceeding gpm per zone. 6. Gears have been stripped out. 7. Crack or break in lateral line.

11 Water Hammer Is your sprinkler system making odd noises? That sound may be water hammer, but then again, there are other things that create noise in water pipes. Air in the pipes can cause them to make sounds which are easily confused with water hammer. Air in the pipes can cause an awful lot of noise! It can be much worse to listen to than true water hammer. The noise of air in the pipes is often a vibrating sound or a rapid ticking sound similar in pace to a machine gun firing. Water hammer can be a big thump that shakes the house, or a series of banging noises starting with a loud bang followed by several "echoes". The best way to identify if the noise is water hammer is to ask your self when does it happen?" To push the air out you need to temporarily increase the water velocity to the point the water pushes out the air bubbles. To increase the velocity you need to turn on as many water outlets as possible. That creates a high water demand and the water velocity goes way up. As the water rushes through the pipe the trapped air is swept along with it and out of the pipe. If the air is in the irrigation mainline (a mainline is the pipe upstream of the circuit control valves) you should be able to increase the velocity by manually opening two or more of the circuit valves at once. Most electric irrigation valves can be manually opened by twisting a lever under the valve's solenoid or by partially unscrewing a bleed screw on top of the valve. Do not remove the bleed screw; just slowly turn it until the valve opens. Open all of the valves at the same time if you need to. Let the water run for a while to give it a chance to push all the air out. When you close the valves close them one at a time. True water hammer is essentially the sound of a "water wreck" occurring. It happens when moving water suddenly changes speed. Water hammer can be caused by a pump starting or a valve rapidly opening, however in the most cases it results when a valve closes. Too much water is trying to squeeze itself through the pipe. To get through the pipe the water moves faster (higher velocity) and the faster it goes, the worse the water hammer gets. You have to reduce the speed of that water to get rid of the water hammer. If the high number of the PSI range given to you by your water supplier is over 80 PSI you should install a pressure regulator on your supply line. You may also add a check valve. Install the check valve as you separate from the supply line right before the main water line for your irrigation.

12 Trouble Shooting Irrigation Controller The first step of troubleshooting an irrigation controller is to verify proper voltage before and after the transformer with a voltmeter. On indoor controllers, this mean verifying you have 120VAC at the outlet and then testing for 24VAC where the cord from the plug in transformer connects to the irrigation controller. On outdoor controllers, you need to check for 120 VAC where the incoming power attaches to the transformer and then check for 24VAC coming out of the transformer. If you have 120VAC being supplied to the transformer, but do not have a 24 VAC output, replace the transformer with correct model replacement part. It should be noted that often power surges can short out transformers. If the transformer checks out ok and there is still no power being supplied to the controller, check the fuse (if applicable) on controller. Some irrigation controllers are equipped with fast blow fuses. Remove the fuse and check the thin filament. Always replace blown fuses with same amperage fuse. Blown fuses are an indication of power surges that could also short electric valve solenoids in the field. Programming the controller To get the most out of an irrigation system the irrigation controller must be programmed properly. Most of us have landscaping which is functional and pleasing but not intricate in design or maintenance. Therefore keep the programming as simple as possible. Most of us will not need to use all the programs and start times available on the controllers. The only times these extra s may come into play is in the initial establishment of the landscape. The basic program consists of inputting the date, present time of day, and the year. After that select program A and input the days of watering needed, the zone run times and the start time(s). The irrigation frequency and run times are dependent on the climate, soils and plant materials.

13 Terminology for controller: Programs: Most controllers come with at least 2 and up to 4 programs. Programs allow you to apply different watering schedules to various types of plant material that have non-similar watering requirements. For example, annual flowers planted in raised beds may need to be watered everyday whereas grassed areas may only need to be watered 3 days a week. In this scenario annual flowers may be on program A and lawn areas on program B. It is important to note that whenever information is entered into the controller under any of the various programs, each program will run concurrently regardless of the program positioning switch or screen display. Start Times: The start time is the time at which you want the controller to begin watering. Once the start time is set, controllers begin the watering cycle with the first station; the other stations in the program follow in sequence. You generally have only one start time, unless you want different zones to come on at different times of the day. If there are multiple program start times on the controller, all zones will run and then start all over. Cycles: The cycle section of the controller refers to the daily interval that the program will run. Most controllers give you 4 options on how you can run the daily intervals. Odd- This setting runs the program every other day on the odd numbered calendar days. Even- This setting runs the program every other day on the odd numbered calendar days. Custom- Lets you choose exactly which days of the week the program will run. Cyclic- Allows watering at a preset interval.

14 Irrigation Definitions: Service Line or main water line: The pipe which carries water to the zone valves. Lateral Line: pipe downstream from each zone valve. Any particular lateral line will not be under pressure unless that particular station is being watered. GPM: Gallons Per minute, this refers to the amount of water your irrigation system receives through the pipes. PSI: Pounds Per Square Inch Pressure, this refers to the pressure of water being supplied to your irrigation system. Operating Pressure: The pressure at which a device or irrigation system is designed to operate at. Backflow Preventer: An absolutely critical piece of equipment which serves to prevent the flow of contaminated water from the lateral lines back into the public water supply. Ball Valve: A type of valve in which a round ball rotates to turn the flow on and off. The ball has a hole through the center such that water flows when the hole is aligned parallel to the direction of flow. Electric Valves: The electric valve that supplies water to one zone, or portion of the irrigation system being operated by a controller. Zone or Station: A portion of the sprinkler system with several sprinklers activated by one output from the controller. While usually only one valve is connected to each output, it is possible for two or more valves to be connected to one station if the controller transformer can handle the load. Controller: A mechanical or electronic device which instructs the station valves to operate. Spray sprinkler: A type of sprinkler where water is thrown evenly across the watered area at all times. The spray pattern is fixed and does not move during watering. Pop-up Sprays: A sprinkler that rises from its case when pressure is applied to the sprinkler, and retracts when the pressure is shut off.

15 Rotor sprinkler: A type of sprinkler where a stream of water is moved back and forth across the area being watered. While the watering is not uniform at any one instant, it is uniform over a period of several minutes or longer. Gear Driven Rotor: A type of rotor sprinkler where the rotating motion is achieved by water driven gear mechanism. Impact sprinkler: A type of rotor sprinkler where the rotating motion is provided by a moving arm which strikes the water jet leaving the nozzle. Nozzle: The part of a sprinkler that defines the spray pattern. Riser: A fixture, usually used in shrub areas, on which a nozzle is attached. Risers do not move up and down at the beginning and end of the watering cycle. Precipitation rate: The depth of water distributed on the ground over a given period of time. Drip irrigation: Water is delivered at or near the root zone of plants, drop by drop. Pressure Reducing Valve: The purpose of the PRV is to reduce the pressure to the sprinkler system when excess pressure is present. PVC: Poly Vinyl Chloride, a type of plastic used for irrigation pipe and fittings. Pressure Loss: The term given for the loss of energy, in the form of pressure, that occurs whenever water moves through a pipe or any other piece of irrigation equipment.

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