It is recommended that a qualified licensed contractor winterize your irrigation system no later than November 1st. The blow out method utilizes an air compressor with a Cubic Foot per Minute (CFM) rating of 80-100 for any mainline of 2" or less. These types of compressors can be rented at your local equipment rental yard. The compressor is attached to the mainline via a quick coupler, hose bib or other type connection, which is located after the backflow device. Compressed air should not be blown through any backflow device. To start the "blow out", shut off the irrigation water supply and, with the compressor valve in the closed position, attach the air compressor hose to the fitting. Activate the station on the controller that is the zone or sprinklers highest in elevation and the furthest from the compressor. Close the backflow isolation valves. Then slowly open the valve on the compressor; this should gradually introduce air into the irrigation system. The air pressure should be constant at 50 PSI. If the sprinkler heads do not pop up and seal, increase the air pressure until the heads do pop up and seal. The air pressure should NEVER exceed 80 PSI.

Each station/zone should be activated starting from the furthest station/zone from the compressor slowly working your way to the closest station/zone to the compressor. Each station/zone should be activated until no water can be seen exiting the heads, this should take approximately two minutes or more per station/zone. It is better to use two or three short cycles per station/zone than to have one long cycle. Once the station/zone is dry, you should not continue to blow air through the pipe. Compressed air moving through dry pipes can cause friction, which will create heat and the heat could cause damage.

Additional Steps

Once the water has been removed from the irrigation system, disconnect the air compressor and release any air pressure that may be present. If your backflow device, the most common backflow installed is called a Pressure Vacuum Breaker, has ball valves, open and close the isolation valves on the backflow device numerous times to ensure that any trapped water has escaped from the upper areas. Leave the isolation valves open at a 45 degree angle (approximately 1/2 open) and open the test cocks.

Outdoor mounted controllers?
Leave the power on and the dial / switch in the "Off" position. The heat from the transformer will keep the enclosure warm enough to keep condensation from forming inside the controller enclosure. The dial in the "OFF" will keep the controller from activating the solenoids in the field.

Indoor mounted controllers?
You may either leave the power on and the dial/switch in the "Off" position OR you may remove the battery backup and unplug the transformer.

Rain Sensors?
There is not much to do to prepare the rain sensor for the winter months. If your sensor is the type with a cup or bowl that catches water, you might want to remove the water and place a plastic bag over the sensor. This will keep any water from accumulating and freezing in the cup or bowl area. If your sensor is the type that uses wafers or discs, you might want to remove the wafers and store them in the garage for the winter months. This will keep damp wafers from freezing.

The Do NOTS of "BLOW~OUT" Winterization

1. Do not allow the air pressure to exceed 80 PSI for systems with PVC piping and 50 PSI for systems with polyethylene piping.
2. Do not stand over component parts while the system is pressurized with air.
3. Do not leave the air compressor unattended.
4. Do not blow the system out through a backflow or pump. First blow out the system, then drain the backflow or pump.
5. Do not leave the manual drain valves open after the blow out.