A Landscape Contractor's Guide to Winterization
Goal of Winterizing Irrigation Systems
The chill autumn air is upon us, which means that now is the time to winterize your irrigation systems! Your sprinkler system is an investment that requires seasonal maintenance. Properly winterizing your irrigation system is critical to preventing damaged pipes and backflow devices.
Ruptured pipes and backflow devices can result in very costly repairs. When water freezes and expands within an irrigation system, it can cause damage. The overall goal of winterizing is to get all the water out of the irrigation system to prevent damage from freezing temperatures. The damage can take place in any component of the system: sprinklers, filters, fittings, pipe, pump casings, or backflows. All components are susceptible to cracking, resulting in a leaky irrigation system and a whole lot of money wasted.
Winterizing an irrigation system correctly, will save you time and money. Not only is it critical to winterize irrigation equipment prior to freezing season, but it’s also an ideal time to perform preventative maintenance and repairs on your system, once all the water has been removed.
Understanding the Frost Line and Its Importance
Here in Southern Ontario, a buried depth of 3 feet is generally a safe distance from the surface to protect your pipes from freezing. However, often pipes are not buried that deep, as deeper trenches can add expense to irrigation installation. If your pipes are buried above that 3 foot threshold and you don’t perform a timely, successful blow out of your irrigation system, you may find significant damage when you go to start up your system in the spring.
Key Considerations for Winterizing Irrigation Systems
There are some important aspects to keep in mind before you begin preparing your irrigation system for the winter. Does the landscape have any above ground piping, RP (Reduced Pressure) backflow or PVB (Pressure Vacuum Breaker) backflow? Damage to any of these aboveground components due to freezing will cost significantly more than the cost of proper winterization. Many backflow preventers are above ground, and therefore exposed to the elements. Furthermore, they are made of metal, making them a target of freezing as soon as the temperature drops. If the system contains a double check valve completely underground or inside the building, you may be able to buy a little more time before winterizing. However, in regards to all aboveground components and any shallow piping, temperatures below -1 degree Celsius indicates that the system needs to be shut off and blown out immediately. Regardless of your system components though, it is a best practice to winterize your system before the temperatures consistently dip that low.
How to Winterize a Sprinkler System Using the Blow-out Method
The blow-out method is the preferred process for winterizing your irrigation system. This method involves blowing high-pressure air through the pipes to force out any remaining water in the system. Below is a step-by-step guide for landscape contractors to blow out a sprinkler system.
First, the water needs to be shut off at its source. In a home environment, this might be in the basement. In a commercial environment, this might be either within a building on site, or in a pit in the ground. Turn this handle 90 degrees such that it is perpendicular to the pipe. Only once the water is off can you safely hook up an air compressor and blow the water out of your system.
All irrigation systems will have a backflow device. Once the water is off, you will need to isolate the backflow to prevent air from traveling backwards. Next, you must remove the blowout cap carefully to release the pressure. The adapter, also known as a “Chicago Fitting”, then connects between the blowout cap and the hose. It is critical to connect after the backflow preventer to prevent causing damage.
Before firing up the compressor, you must manually turn on the controller to Zone 1, as you can’t allow pressure to build up on a closed system. Then, you should manually go through each individual zone until all the water is out of the system.
At the compressor, you must open the ball valve, then fire up the compressor. Most irrigation system blowouts will require a compressor to be run at 60-80 PSI. Too much PSI will blow out the sprinkler heads, whereas insufficient PSI will not adequately remove all the water. While some homeowners may own compressors that could generate that kind of pressure, an industrial-capacity compressor will generate the volume required to winterize a commercial landscape’s sprinkler system more thoroughly and quickly.
Each zone will sequentially be cleared of water. Begin at the zone furthest from the compressor and work your way toward the main water line. Initially, a steady stream of water is released. As the water works through the system, the head sprays a fog, indicating the zone is done. Once a zone is cleared, you can turn it off manually or via controller. After this signal that the system is clear, the compressor is shut down. At this point, water has been cleared from the discharge side of the backflow device out to the sprinkler heads.
Finally, to remove the very last water remaining through the backflow device between the hose point of connection and the backflow valve, you must follow 3 steps. (1) Disconnect the hose, (2) disconnect the adapter, and (3) put the cap back in gently to allow any remaining drips to get out. Next, turn each ball valve a quarter turn to allow any trapped water inside the valves to get out and prevent cracking. Similarly, the ball valve of each test cock receives a quarter turn to give any remaining water an opportunity to escape. Lastly, get back to the hose point of connection and open the drain to remove the final bit of remaining water in the supply line.
Note that while this method of irrigation winterizing describes a simpler commercial or residential system, it is scalable to any size of irrigation system. Winterizing a larger commercial system requires the exact same process with a few extra steps. Some common differences with larger systems include booster pumps, flow meters tracking water volume, and insulated enclosures, which may provide pipes some protection from the elements.
Isolating the Irrigation System
It is critical to isolate the system one valve at a time into small sections to ensure water is removed all the way. For example, a golf system may have one long main line with many lateral lines running from it. Valves on each line must be opened sequentially in order to isolate individual portions of the irrigation line. Blowing out just the main line will not protect the lateral lines, and often would provide more damage to the lines running to the rotors on each hole.
What Size Compressor Will You Need?
Any compressor that can generate 60-80 PSI should be sufficient for most commercial irrigation winterizing jobs. Cubic feet per minute (CFM) measures the volume of air being pushed through a pipe over time. The cubic feet per minute should exceed by at least 2x the gallons per minute (GPM) of water that a pipe allows. Without at least 2x the CFM, winterizing the irrigation system will take an excessively long time.
Where Does Winterization Typically Fail?
Even while following each step in the winterization process in a textbook manner, damage may occur. As a commercial landscape contractor, it is important to be aware of potential pitfalls in the winterization process, so that you can take extra care to avoid them.
Flow meters: Most flow meters contain a spinning paddle wheel. This wheel has the potential to sustain damage from the force of air being blown through the system. Damage to the flow meter may result in future inaccurate water flow readings.
Backflows: Most often, damage to the backflow results from water in tight spaces not being properly removed. Unfortunately, this tends to happen frequently on a mainline, and results in an active leak. This can be avoided by carefully following the itemized steps listed above.
Sprinklers: Sprinklers contain many components involving multiple gears, rotors, check valves, pressure regulators, and turbines, which can harbour the remaining water. As a landscape contractor, one low-tech method you can use to check a sprinkler head for remnants of water is to step on it to create a small amount of turbulence.
Valves: While there are many different styles of valves, the ball valve is the most notorious for trapping water. Its very nature consists of an open ball on one side, designed to allow water to lubricate its opening and closing. However, its design can also be a trap for water if not closed a quarter turn to allow the remaining water to be removed. A 45-degree turn will allow any water in the valve to drain down into the pipe, thus preventing a costly rupture.
Winterizing your irrigation system is crucial to maintaining your system in colder climates. Not doing so can lead to broken pipes, backflow device damage, and expensive repairs. An irrigation system is a significant investment for commercial landscaping, and it deserves careful, skilled maintenance to allow it to perform at its best each growing season.
If you have questions or challenges regarding winterizing your irrigation system, our expert team can offer you useful advice and the best solutions. As national leaders in irrigation products, we can provide the tools and expertise you need to give your irrigation system the maintenance it deserves.
Reach out to our solutions-oriented experts at the Vanden Bussche location nearest to you, or contact us online, and one of our experts will get in touch with you soon.