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.

“Using Your Smarts” With Smart Irrigation Controllers Featuring JC Wheaton

Lawn & Landscape January 2016 CoverJ.C. Wheaton, President of the Ohio Irrigation Association and manager of Centerville Irrigation in Ohio, was recently featured in Lawn & Landscape’s article entitled, “Total Control.” Smart Irrigation controllers are the next step in the efficient use of water in the landscape.

J.C. was interviewed about Smart Irrigation Controllers, calling the new technology “the responsible thing to do.”

JC Wheaton Head & ShouldersWheaton’s company installs a controller with a smart sensor, capable of sensing local weather conditions. The sensor then automatically alerts the controller to the current conditions, eliminating the need for human manipulation.  This is something customers appreciate, because “it saves them from either having to go to the box themselves or calling us for a return trip,” Wheaton said.

One-Stop Service

Customers also love the fact that the system is a “one-stop” service that automatically adjusts to the temperature.   “They don’t have to go out three times or four times a season to adjust everything.”  He considers this the system’s strongest selling point for new customers.  “You’re saving them the hassle with keeping the property the way they want,” he said.

While Wheaton admits that the smart controller system costs more than a traditional controller (still less than $100), he believes the energy and water savings make it a much better long-term deal.

More Commercial Use Needed

commerical-sprinklersWhich is one reason he hopes commercial architects and designers will jump on board to maximize efficiency of their designs.  Right now, the smart controller systems are not very well stocked on commercial projects, and that’s resulting in poor efficiency.  “You see them all the time running in the rain, no matter what town you’re in,” Wheaton says. “Running too long, running in the gutter…because they were not put in correctly with the right components.”

The Down Side?

One of the potential drawbacks to the smart controller system is losing control of when the zones are running. “You’re basically turning that over to the clock to make those decisions, which isn’t always a bad thing. But sometimes the homeowner or resident wants to know their irrigation schedule and you can’t necessarily tell them that,” Wheaton said.

Companies will also see fewer mid-season service calls. Contractors who are concerned about that are probably not the type who will benefit from using the smart control system, Wheaton said.  “It’s about the efficiency of getting the best product to your customer. Those callbacks can be used other ways, such as zoning and monthly business checks.”


Source:

Lawn & Landscape, http://www.lawnandlandscape.com/article/total-control/