Winterizing the system poses potential risks, so it's best to hire a qualified professional. Even if you drain some water from the system, there's a risk that the remaining water will freeze, expand, and cause the PVC lines (rigid, white pipe) to rupture, usually connecting quick-connectors.
In many countries with freezing weather, polyethylene pipes (flexible, black pipes) are used. Although polyethylene pipes are more flexible and expand under pressure, residual water can freeze and cause the pipe walls to crack. Ice water in the backflow device damages internal components and can even burst brass housings.
Preparation steps
To minimize the risk of frost damage to your irrigation system, it's essential to winterize your system. Irrigation systems in areas where winterization is a must are installed for one of three types of water drainage:
- Manual drain
- Automatic drain
- Blowing out with compressed air
If you don't know your system type, it's best to use the blow-out method.
Manual drain method
Use these if you have manual drain valves installed at the end and low points of your irrigation lines. To drain these systems, simply shut off the irrigation water supply (the shutoff is located in the basement and is either a shutoff valve, ball valve, or a shut-off and drain valve—see drawings below) and open all manual drain valves.
Once the water has drained from the main line, open the boiler drain valve or the drain cap on the shut-off and drain valve (depending on which one is used for your area) and allow any remaining water between the irrigation shut-off valve and the backflow device to drain. Open the control valves on the backflow device.
If your sprinklers have check valves, you'll need to lift the sprinkler head to allow the water to escape from the bottom of the sprinkler body. Depending on the location of the check valves, some water may still be trapped in the return line, the pipes, and the sprinklers.
When all the water has drained, close all manual drain valves.
Automatic drain method
Use these if you have automatic drain valves installed at the end and low points of your irrigation lines. These will automatically open and release water when the pressure in the lines drops below 10 PSI.
To activate it, turn off the irrigation water supply (shutoff is located in the basement and is either a shutoff/isolation valve, ball valve, or a shut-off and drain valve - see drawings below) and activate a station to allow the pressure in the system to drop.
Once the water has drained from the main line, open the boiler drain valve or the drain cap on the shut-off and drain valve (depending on which one is used for your area) and allow any remaining water between the irrigation shut-off valve and the backflow device to drain away.
Open the check valves on the backflow device. If your sprinklers have check valves, you'll need to lift the sprinkler head to allow the water to escape from the bottom of the sprinkler body. Depending on the location of the check valves, some water may still be in the backflow, the pipes, and the sprinklers.
In some areas, you may have a combination of a manual drain system on the main line (the line between the irrigation shutoff valve and valves) and an automatic drain system on the laterals (the pipe between the valves and sprinklers).
“Blow-out” method
Warning!
Wear ANSI-approved eye protection! When draining the system with compressed air, proceed with extreme caution. Compressed air can cause serious injuries, including serious eye injuries from flying debris. Always wear ANSI-approved safety goggles and stay away from irrigation components (pipes, sprinklers, and valves) while using compressed air. Failure to follow these recommendations could result in serious injury.
It is recommended that this method of winterizing be performed only by licensed irrigation companies.
The blow-out method uses a compressor with a flow rate of 80-100 cubic feet per minute (1 cubic foot = 28.3 liters) for all main lines 2 inches or smaller. These types of compressors can be rented from your local equipment rental shop.
The compressor is connected to the main line via a quick-connect coupling, hose connection, or other type of connection located downstream of the backflow device. Compressed air must not be blown through backflow devices.
To begin the "blowout," disconnect the water supply and connect the compressor hose to the quick-connect connector with the valve closed. Use the controller to activate the zone or sprinkler that is highest and farthest from the compressor. Close the return shutoff valve.
Then slowly open the valve on the compressor. This allows air to gradually enter the irrigation line. The compressed air should be below the maximum working pressure of the lowest-pressure component in that zone and NEVER exceed 80 PSI.
Each station/zone is activated one at a time. Start with the one farthest from the compressor and work your way from station to station toward the compressor.
Each station/zone should be activated until no more water flows from the heads. This can take two minutes or more per station/zone. It's even better to use two or three short cycles per station/zone instead of one long cycle. Once the station/zone is dry, stop blowing air through the tube.
Compressed air forced through dry pipes can cause friction, which generates heat and can cause damage.
Additional steps
Once the water has been removed from the irrigation system, disconnect the compressor and allow any air to escape.
If your backflow device (the most commonly installed backflow is a pressure vacuum breaker) has ball valves, open and close the shutoff valves on the backflow device several times to ensure that there is no water left in the upper areas.
Leave the shut-off valves open at a 45° angle and open the control valves.
Preparation of hydraulic control system
Disconnect the water supply to the signal cable(s) and allow the field lines to drain.
Preparation of freely mounted control units
Leave the power supply connected and turn the switch to the "off" position. The heat from the transformer keeps the enclosure warm enough to prevent condensation from forming inside the control unit. Because the control unit is in the "off" position, the electromagnets in the field are not activated.
Preparation of interior-mounted control units
You can either leave the power connected and turn the switch to the "off" position OR remove the backup battery and unplug the transformer.
Preparing rain sensors
There's not much to do to prepare rain sensors for winter. If your sensor type uses a cup or bowl to collect water, it's advisable to remove the water and cover the sensor with a plastic bag. This will prevent water accumulation and ice formation in the cup or bowl area.
If your sensor type uses discs or plates, it's advisable to remove them and store them in the garage during the winter months. This prevents damp plates from freezing.
What should be avoided when preparing for winter with compressed air
Warning!
Wear ANSI-approved eye protection! When draining the system with compressed air, proceed with extreme caution. Compressed air can cause serious injuries, including serious eye injuries from flying debris.
Always wear ANSI-approved safety goggles and stay away from irrigation components (pipes, sprinklers, and valves) while using compressed air.
FAILURE TO FOLLOW THESE RECOMMENDATIONS CAN RESULT IN SERIOUS INJURY!
- For systems with PVC pipes, the compressed air must not exceed 80 PSI, and for systems with polyethylene pipes, the compressed air must not exceed 50 PSI.
- Do not lean over component parts while the system is being blown out with compressed air.
- Never leave a compressor unattended.
- Do not purge the system using a backflow or pump.
- First blow out the system and then empty the backflow and pump.
- Do not leave the manual drain valves open after blowing out.
Professional help with winterizing
As a certified specialist company, Wassermann360 offers reliable services for winterizing irrigation systems. Our experts professionally carry out all necessary steps to prevent frost damage to your system. They use modern methods such as the compressed air blow-out method.
Benefit from our many years of experience and the expertise of our specialists. We will provide you with comprehensive advice and tailor the optimal approach to your irrigation system. We would also be happy to provide you with a non-binding quote.
Contact us for professional support with winterizing! Wassermann360 is at your side as a competent partner with reliable service.