Winterizing a Landscape Irrigation System

(Note: This article originally appeared in SportTurf Magazine)

Winter ImageThe dreary days of November remind us that it’s time to start thinking about preparing your irrigation systems for winter. Water expands when it freezes. Since automatic irrigation systems are usually buried only about twelve inches below the surface of the soil, water left in an irrigation system in freezing climates over the winter, even a mild winter, will certainly freeze — causing damage to pipes, fittings, valves, and sprinklers. Damage caused by a frozen irrigation system can be expensive and time consuming to repair next spring. Preventing winter damage by properly winterizing the irrigation system is important. Using compressed air to force water out of the irrigation system is the most common method of winterization. However, irrigation systems equipped with automatic or manual drain valves do not require compressed air to winterize. Only the installing contractor will know if an irrigation system is equipped with automatic or manual drain valves. If you are not sure what type of irrigation system you are winterizing, then use compressed air. Using compressed air on an irrigation system equipped with automatic or manual drain valves will not harm the components of the irrigation system, and will ensure the irrigation system is properly winterized.

Selecting an Air Compressor

Sulliar 185 Portable Air Compressor

Sulliar 185 Portable Air Compressor

A properly sized air compressor is critical in effectively and efficiently blowing air into the irrigation system, forcing any water out. Air compressors are available in various sizes. The most common portable air compressor, which represents roughly 80% of the portable air compressors going into rental fleets today, is the 185 portable air compressor. This machine is rated at 185 cfm at 100 psi at full load. You can find one through a contractors’ equipment rental shop that is more than adequate to get the job done for most residential and commercial irrigation systems. Smaller 5 h.p. electric air compressors, although capable of delivering 100 psi, are not capable of delivering enough volume of air to adequately winterize an irrigation system.

Compressed Air Winterization

The first step in winterizing an irrigation system is to shut off the water to the irrigation system at the point of connection. The system shut-off valve may be a ball valve or gate valve located in the basement or directly after the water meter. Then open a zone valve to relieve the system pressure. Attach the air hose from the air compressor to the blow-out point. The blow-out point is usually located directly after the backflow device. The blow-out point may be a quick coupling valve, a hose bib, or a boiler drain. In this technical drawing the blow-out connection is the quick-coupling valve located in the valve box.

A note of caution: The expanding air coming from the air compressor into the irrigation system will get hot and may melt the plastic pipe. Carefully check the temperature of the air-hose connection at the blow-out point. Slow down or stop momentarily if it feels too hot! Cycling through each zone two or three times for short intervals will prevent too much heat buildup.

 

Winterizing an irrigation system with compressed air

Air Compressor Settings

Set the pressure regulator on the air compressor at 50 to 80 psi. On smaller residential systems, where the zones are typically about 10 gpm or less, open one electric remote control valve manually and cycle through all the other zones two to three minutes by manually opening each valve or by electrically operating each valve at the controller. Opening one valve manually will help to keep the air com- pressor from building up too much pressure while assuring an adequate volume of air to thoroughly blow out all the water in the sys- tem. On larger systems it may not be necessary to open one valve manually. Allow the air to flow through each zone until water and water vapor no longer appears from any sprinklers in the zone. Start with the zone with the highest elevation in the system or farthest from the point of connection, blowing out each zone successively toward the point of connection. It is a good idea to cycle through each zone two times to ensure there is no water remaining that might settle into a low point in the lateral pipe.

Automatic Drain System Winterization

Although using compressed air is the most common method for winterizing an automatic irrigation system, there are two other types of automatic irrigation systems. The first type is a system equipped with automatic drains. The automatic drains open when the system pressure falls below 10 psi. For these systems it is usually only necessary to turn off the water. Open a drain valve after the point of connection. Prepare the backflow device and controller for winter as noted below. Some irrigation systems incorporate automatic drain valves on the laterals and manual drain valves on the main line. The manual drain valves will be located in small valve boxes at the end and at low points on the main line. Open the drain valves, and allow the water to drain out completely. Then close the drain valve.

Manual Drain System Winterization

An irrigation system equipped with manual drain valves requires you to locate the drain valve for each zone and the main line. The manual drain is usually located in a small valve box at the end of the zone and at every low point. Also, the main line will have a manual drain at the end of the line and at every low point. Open each drain valve, allowing all the water to drain out, and then close the manual drains. Winterize the back- flow device and irrigation controller as noted below.

Backflow Winterization

Backflow Installation Detail

Typical PVB backflow installation.

There are two backflow devices utilized in landscape irrigation systems. The most common is a pressure vacuum breaker. Open the top of the pressure vacuum breaker and remove the internal discs and springs. Storing these components near the irri- gation controller makes them easier to find next spring. Turn the handles on the two ball valves and all test ports to a partially open 45 degree position. Ball valves, when fully closed or fully open, will trap water in between the ball and the valve housing. The valve housing will crack during a freeze if not left partially open.

Some newer pressure vacuum breakers are freeze resistant, with a built-in relief valve to protect the internal components and the body from freezing. It is not necessary to remove the internal components in these devices.

The other type of backflow device used in irrigation system is a reduced pressure principle backflow device, or RPZ. It is usually best to remove this device completely during the winter and store indoors. Then cap the pipes to the irrigation system. If removal of the RPZ back- flow device is not possible, carefully follow the manufacturer’s instructions for winterization. Each manufacturer has specific instructions for winterizing their reduced pressure principle backflow device.

Irrigation Controller and Rain Sensor Winterization

To prepare the irrigation controller for winter, simply turn the contoller to the off or rain shutdown position. You can also disconnect the power and remove the battery but this is not necessary. It is important not to allow the controller to cycle through an irrigation schedule without water in the system because the remote-control valves require water to move through the solenoid assembly to cool the assembly.

If your irrigation system is equipped with a rain sensor or a soil moisture sensor, it is not usually necessary to cover or remove the sensor for the winter. Check with the manufacturer to make sure the sensor does not require any special instructions for win- terization.

Pump Winterization

Submersible pumps, located in a lake or stream, have a check valve at the pump which needs to be removed to make certain the discharge hose does not freeze. It is adviseable to simply remove the pump and discharge hose from water each winter, reinstalling it in the spring.

Centrifigal pumps have a drain valve located at the base of the pump housing that needs to be removed and stored for the winter. The power supply for the pump should also be disconnect- ed to prevent the pump from being accidentally turned on with- out any water. A pump running without water will quickly burn up. Additionally, if the pump is drawing water from a lake or stream, the intake hose has a foot valve located at the base of the suction line. So it is necessary to remove the intake or suction line completely from the water and store it for the winter. Sometimes a check valve is also located on the discharge side of the pump. This check valve needs to be removed and stored for the winter.

Preparing an irrigation system for winter can be a complicated process. A knowledgeable professional is essential to minimize freezing water damage. An improperly winterized irrigation system can be an expensive proposition next spring.

Internet-Based Smart Irrigation Systems

Internet-based smart irrigation system technology is rapidly expanding throughout the industry, particularly for residential usage.web-based

Internet-based smart irrigation system technology is even featured in Forbes magazine, “Tired Of Wasting Water With That Dumb Sprinkler? Meet The Smart Sprinkler Controller.” This irrigation system technology allows residential users to control and monitor their sprinkler systems from anywhere in the world using a web browser or iPhone/Android app. It also uses the homeowner’s wireless internet (wifi) to access a live stream from nearby weather stations.  As a result, residential users are provided with real-time weather data, without the need to install a personal weather station or rain sensor.

lawn1Using adaptive algorithms to generate custom and dynamic watering schedules from this weather data, the smart controller automatically determines the optimal watering schedule for the irrigation site. The system automatically adjusts watering cycles, duration and frequency for optimal results in any weather condition. Some smart controllers will even take into consideration local watering restrictions.

swat_logoWeb-based irrigation systems are certifiable through both the EPA’s WaterSense program and the Irrigation Association’s Smart Water Application Technologies (SWAT) testing.  For a comparison of WaterSense and SWAT testing protocols, click here.

Let’s take a look at some of the web-based irrigation systems currently available…


Skydrop

Skydrop’s WiFi-based smart controller entered the market in September of 2014. The company is based in Lehi, Utah, and promotes its product as helping residential users to abide by local watering restrictions. (“Don’t be a lawn bandit, and don’t risk hefty fines.”) According to Skydrop, the typical homeowner can install and set up its controller in less than 30 minutes.

Malibu-GardenIn addition to using real-time weather data, the Skydrop smart controller also measures soil moisture to determine how much water the landscape is losing.  Like most other internet-based systems, the Skydrop device is programmed by zone according to soil type, plant type, sprinkler type, slope and shape. The  Skydrop controller can also be integrated with other smart home systems such alarm controllers, solar heating/cooling, and outdoor lighting.

logo-90The controller includes a “cycle and soak” feature to eliminate or reduce runoff when landscapes are sloped. The company claims that watering each zone separately and only when required results in an average reduction in water usage of 35%. The Skydrop smart controller has qualified for the EPA’s WaterSense® Certification, yet the company does not plan to pursue SWAT testing at this time.

The Skydrop controller operates eight zones plus a master valve/pump, and is expandable to 16 zones with an expansion unit. The retail price for the Skydrop 8-zone controller is around $300, and the expansion unit retails for $50.


Hydrawise (Hunter Industries)

flowerHydrawise was recently purchased by Hunter Industries. The Hydrawise smart controller provides interactive online reporting and alerts that allow the user to view water usage for each watering cycle or the water flow rate at any time. Email alerts notify the user of water flows (e.g., due to a broken pipe or faulty valve) when no zone is currently running. Alerts can also be configured when the water usage for an irrigation zone changes by more than 10% (such as, from broken spray heads or faulty wiring).

Hydrawise2ColorTrim260Hydrawise is one of the products which does not require port forwarding on the user’s router in order to control the irrigation system from anywhere in the world. Rather, wireless functionality is provided inside the controller; the user enters a wireless password on the controller itself.

hydrawiseAccording to Chris Foster, Midwest Sales Manager for Hunter, the Hydrawise system utilizes Cloud technology, allowing the residential user and support technician to “meet in the cloud,” thereby preventing any potential security risks.  “Hydrawise is fourth-generation technology,” he said.

The Hydrawise controller is available in 6- or 12-zone models; expansion modules allow an individual system to be expanded up to 36 zones. The product is WaterSense certified and was the winner of  The Australian Backyard Innovation Challenge in 2015. Hydrawise has not been SWAT tested. Pricing is available through a Hunter distributor.

According to Michael White, Vice President of Turf & Landscape Sales for Automatic Irrigation Supply, one of the best features of the Hydrawise system is the professional support that is now available through Hunter Industries.


Cyber Rain

The Cyber Rain smart controller is manufactured by Israel-based Galcon, which is owned by Kibbutz Kfar Blum.  According to the company, Cyber Rain was the very first central irrigation product to earn the EPA WaterSense certification (in 2012). It also claims that the Cyber Rain controller can reduce water costs by up to 40% annually. Cyber Rain is SWAT approved.

LogoCyberRain1Cyber Rain supplies a small device called an “Access Point” that is plugged into a router so that the controller can access the internet using Cloud technology. The Access Point communicates with an unlimited number of Cyber Rain controllers through its own two-way wireless network. The standard radio can communicate up to 200 feet, while the longer-range radio can reach up to two miles with the optional antenna.

downloadCyber Rain offers a Smart Scheduling Wizard to set up the water-wise irrigation schedule customized to the particular landscape. For zones with dense soil or on a slope, for instance, the Cyber Rain smart controller offer a cycle and soak feature to avoid run-off.

Controllers are available in 8-, 16- and 24-zone models. (The optional antenna can be attached to increase range.) Prices for the residential systems range from $500 to $600.  Professional installation is not required for the residential systems, but appears to be recommended.


Rachio

Rachio introduced its first product (“Iro”) in 2014; Iro is an intelligent irrigation controller that is powered by Rachio’s cloud-based software.  It an be rachio-logo-for-web-300px (1)controlled either through a web-based dashboard or through an intuitive Android or iPhone app. During setup, the homeowner’s smartphone sends a signal to the Iro, connecting it to the internet through a WiFi network. It then communicates with Rachio’s cloud-based software. The company claims that installation and setup take less than 30 minutes with no special tools or expertise required.

The Iro will automatically check the local weather forecast and issue adjustments based on evapotranspiration and precipitation data to match soil moisture depletion. The Iro also learns from the customer’s adjustments over time. As a result, users can personalize the balance between water use and the level of plant health in each zone.

Irrigation-Flowers013Iro’s Smart Cycle will automatically schedule cycle and soak irrigation events to eliminate or reduce runoff when landscapes are sloped and/or the infiltration rate of the soil is less than that of the precipitation rate of the nozzle for the given zone. A virtual rain sensor will suspend irrigation events if rain is forecasted within the next 24 hours.

Iro controllers are available in 8-zone ($199) and 16-zone ($249) models. The Iro system has received the EPA’s WaterSense certification. Rachis is SWAT tested and has earned the prestigious EPA WaterSense label for irrigation efficiency.

Comparison of Residential Web-Based Smart Irrigation Controllers

 SkydropHydrawiseCyber RainRachio
SmartPhone CompatibleYesYesYesYes
Ipad/PC CompatibleYesYesNoYes
Android CompatibleYesYesYesYes
Uses Real-time Weather DataYesYesYesYes
Provides Online ReportingYesYesYesYes
Uses Cloud TechnologyYesYesYesYes
WaterSense CertifiedYesYesYesYes
SWAT TestedYesNoYesYes
Do-It-Yourself InstallationYesNo
YesYes
Professional SupportNoYesNoYes
Interfaces with Other Home SystemsYesYesNoYes
Includes Cycle and Soak FeatureYesYesYesYes
No. of Zones Available8, 166, 12*8, 168, 16
Price$299.99-$348.99 $260.00-$310.00$499.00-$599.00$199.00-$249.00

*May be expanded up to 36 zones.


The Future

Having recently attended a trade function focused on what water management will look like in the year 2065, Automatic Irrigation’s Michael White firmly believes that the web-based systems are crucial to allowing homeowners to be better stewards of water resources.  “Twenty-five years from now, water will cost much more than it does today,” he said. Consequently, “These new systems are good for the consumer and they’re good for the industry.”

(Editor’s note: Rachio’s data was corrected and updated from the original post based on additional information provided by the manufacturer.)


Sources:

U.S. Department of the Interior Bureau of Reclamation, “Weather- and Soil Moisture-Based Landscape Irrigation Scheduling Devices”