July 2014 - Posts
So we're still in July and still talking about automatic irrigation systems for Smart Irrigation Month. It's seems this week summer has hit (again), maybe "for real" this time, so an efficient irrigation system is more important than ever.
I'm going to continue the same topic as last time, which is upgrading your irrigation system when necessary. We talked about sensors last week. This week I'd like to focus on sprinkler heads and water pressure. The type of sprinkler head being used determines several things, like how long to water, where to locate the heads, and also how much water is being emitted and, most importantly, how well that water is being used by your landscape.
There are two main types of sprinkler heads-spray heads and rotor (or rotatory) heads. Both are usually located unground and pop-up when it's their time to water.
The spray heads are the ones that water the same piece of grass, or landscaping, the entire time they are popped up. Rotor heads rotate to the left and right when they pop-up and do not water the same place the entire time they are popped up. See the pictures on the right for what each look like.
Rotor heads are the more efficient of the two head types. Tests have shown that the water is distributed more evenly by rotor heads than spray heads. The same amount of water is being emitted close to the head as midway as at the furthest end of the water. Usually people want to replace rotors with sprays, but I urge them not to. Again, they are more efficient than traditional spray heads. They emit, on average x gallons of water per minute. Rotor heads are desirable to use in large areas-fewer heads are required to cover a large space since they spray water out a further distance than spray heads.
Traditional spray heads are not quite as efficient, mainly due to variations in water pressure and head spacing (specifically heads placed too far apart). Misting is pretty commonly seen with spray heads-this is lots of "clouding" coming off the heads. This cloud, or misting, is water drops that are so small they are just floating away into the air, rather than going down onto the landscape. (See the picture, all that stuff in the air above the plants is the water droplets from the irrigation system). You are paying for this water and it's just floating away. Not good. This means you have to run the system for a longer time to get water down onto the ground, which will get expensive and is just wasteful. This is caused by water pressure that is too high.
An aside here, "good" or appropriate water pressure for irrigation systems is between 30-50 psi.
High pressure can be remedied in two main ways: installing a pressure reducing valve (PRV) on the irrigation system, or replacing the nozzles with ones that adjust or compensate for the high water pressure. So...which is better? That's a hard question to give a quick answer for.
The PRV is a good fix if the entire irrigation system is running with high pressure. It's one device that is installed near the backflow prevention device in your yard. A licensed irrigator should be contacted to install this device.
Replacing nozzles is a great way to fine-tune the irrigation system; here, you can just replace nozzles in the zones that have the high misting. This is a little more time consuming because you need to find and purchase the correct nozzle types (full circle, half circle, etc) and then physically unscrew the old nozzles and screw on the new ones, but overall it's pretty inexpensive. Of course, a licensed irrigator can be hired to do this work as well. There are several brands of nozzles that have built-in pressure compensation and can be ordered online or found in local irrigation stores.
Both of these types of pressure reducing efficiency qualify for the City's Efficient Irrigation Rebate program. I highly encourage you to take advantage of it if you notice misting in your irrigation system!
The first thing I saw when I turned my computer on Friday morning was emails from co-workers and City residents voicing concern about the irrigation systems they saw running this morning-after receiving 3+ inches of rain! It's crazy, I know.
I don't think anyone deliberately chooses to look silly or be wasteful by watering during or immediately after a huge rainstorm, they just don't actively think about their irrigation system. For commercial properties, it's bad for their image to look so wasteful, so I would think they'd be the first to jump on the efficient bandwagon and make sure the irrigation is always working as efficiently as possible. Unfortunately, that's not always the case--and not just with commercial properties. This brings me to my second topic for Smart Irrigation Month-Upgrading your Irrigation System.
Updating, or improving irrigation systems, in my experience, tend to happen mainly when other big yard activities are going on, such as installing a pool or a new patio, or deck; replanting the sod or a huge remodel of all the landscaping in the yard. I don't really see folks upgrading their systems just because there's a new model of controller, or cool sensor. While irrigation is technology, apparently it's not the cool technology that people invest in as frequently as their portable, hand-held electronic devices. I think it's because we don't visually see them or think of them nearly as much as our phones, or portable devices. They seem to do a good job-the grass is alive, so what's to change? Well, technology has come a long way in the last decade in irrigation systems, which can save you money in water costs, conserve water, water more to the plant's needs, and maybe have a little cool factor when you talk about your yard with your friends!
I don't want this article to go too long, so I will focus only on sensors today. Rain sensors are required on all newly installed irrigation systems since January 1, 2009. Though they have been around many years prior to that, they generally weren't installed very frequently even though they are relatively cheap.
- Sensors include rain sensors, freeze sensors, and soil moisture sensors. All of these are separate devices that are wired into the main irrigation controller, they do not come installed as part of the controller. Some controllers have a switch on them that says "sensor active" and "sensor bypass", that doesn't mean there is actually a sensor installed on your system.
A rain sensor turns off the irrigation system (if it's running) after a specified amount of water has fallen or it delays the system from turning on after a specified amount of rain-so all of its actions are during or after the rain. There's no weather forecasting, or determination of if watering is necessary. They have to be installed in an unobstructed location (like a fence or roofline) so that rain can fall in it. I've seen them under trees and under buildings! (see the picture for proof). But, it is better to have a working rain sensor than nothing, as I wish some commercial properties would have this morning! By the way, they're pretty cheap-about $35-$75 retail.
Tremendous improvements have been made in the soil moisture sensor arena. A soil moisture sensor is actually buried in the ground about 6-inches deep (yes, you have to have that much soil for these to work!). They take moisture readings from the soil to determine if the soil is dry enough to require the irrigation to run; if it determines the soil doesn't require additional water, it doesn't allow the system to run. Ideally, you'd want more than one soil moisture sensor installed in your yard, one in sunny area and one in a shadier area, otherwise parts of your yard may be under- or overwatered. It's more accurate watering than just watering because it's a Saturday. It's watering because the soil actually is dry. They are a little more costly than rain sensors, but they provide a more effective use of water.
Freeze sensors do not allow an irrigation system to turn on when temperatures reach a specific degree, usually around 40° F. These aren't that common to have at homes, because we just turn off our irrigation systems for the winter. Commercial properties tend to water more year-round and would benefit from a freeze sensor to prevent the irrigation from freezing and causing a hazard.
The City's Efficient Irrigation Rebate provides a rebate of 75% of the purchase cost of a sensor for your existing irrigation system, so if you don't currently have a working one, please get one and apply for the rebate!
July has been deemed "Smart Irrigation Month" by the Irrigation Association since 2005, because that's typically when the hottest temperatures occur. With high and hot temperatures come higher water use, it's just a given. We still want our landscapes to look as good as they have the rest of the year, so we crank up the water.
This year, I'd like to challenge you to do something different. It's been a slightly different year already: we didn't have a 100-degree day until this last week! We've had regular rainfall all throughout May and June. We really haven't needed to use the irrigation system until this month. So, in honor of Smart Irrigation Month, I'm going to write a short series on automatic irrigation systems, in which I'll (1) encourage you, and explain how, to maintain your irrigation system, (2) upgrade it where necessary, and (3) schedule it efficiently and effectively based on your plants, light, and sprinkler head type.
Performing a check of the irrigation system, (aka an Irrigation Evaluation, or Irrigation Audit) is the cornerstone for maintaining the system. If you are a direct water customer of Round Rock, Water Conservation staff will schedule and do this for you; however, it's simple enough that you could do it yourself-and it's highly recommended to check you system monthly! I recently found a broken head on my own system that I hadn't noticed or even realized was there. So, how do we check it?
1. First you need to go to the controller and turn the dial to "test" or "system test" if that option is there (Rainbird controllers have this). If you have this option, great! The number you see in the display are minutes that, once started, will run each station for x minutes and then turn off. A good default number is 2 minutes. After selecting 2 minutes, push the manual start button on the controller to begin the system test.
2. If you DO NOT have the "test" option on your controller, you can simply program one in. Just choose a program that you are not using for your normal watering cycle-probably the C program. You don't need to enter in start times or water days, only watering times; so for each of your stations, enter a runtime of 2 minutes. Then start the program manually.
3. Once the system is running, you are looking for problems, issues like sprinkler heads turned the wrong way and spraying the street, rather than the grass. Or heads that do not pop-up over the grass (that's why there's that dry spot!), or heads that are clogged, and no water is coming out of them. You could also look for leaking heads, broken nozzles, and other leaks. For an idea of what some of this looks like, see my blog "What is Water Waste?" from last month.
a. The simplest, and most worthwhile, thing to fix is misdirected heads; most of them can simply be turned to face the appropriate direction by using your hand to grab the head (essentially the neck) and physically turn it. This prevents water waste, poor coverage, and ensures the water is used, rather than running off the property; all of which are positives for you and your property.
A big clue that you have misaligned heads and overspray is if you can tell your sprinklers ran--meaning you can see the water on the street, on the driveway, on the sidewalks, on the patios, etc., like this picture to the right!!
b. Nozzles that are clogged are easily be cleaned out (when the system is turned off!). Unscrew the nozzle, rinse it and the filter off, and screw it back on. You may use an old toothbrush or toothpick to clean out the emitter where the water sprays out of the nozzle, it's pretty small. Once screwed back on, turn the system on to make sure you have put it on facing the correct direction and it's watering what it needs to be.
c. Low heads or heads that do not pop-up over the grass is due to either too tall grass, which is really not a bad thing, usually, or more likely, the heads have settled over time and just sunk into the ground. They need to be replaced with taller heads in order to have better coverage-to get the water out far enough to water what's it's supposed to. You can replace this head yourself with a taller head (they are sold by height in inches, so if you have a 4" head currently, you may increase to a 6"), or depending on the amount of low heads, you may hire a licensed irrigator to do this, as there is a degree of professionalism needed. You don't want the heads sticking up over the grass and become a hazard when the grass is mowed.
So that's the basics of performing a system check! Do it monthly to physically see how the system is working, that what is supposed to be watered is actually being watered, AND, most importantly, make repairs and adjustments to the system to keep it running efficiently!