Sprinkler systems need to have all the water blown out of them before winter freeze-up. If you have an air compressor you can do the job yourself and save the hefty service fee.
Close off both valves on the backflow preventer. Then remove the plug on the blow-out port and screw in a quick-connect hose adapter. Snap on the air hose and connect the other end to the compressor.
With a basic quick-connect coupling, you can use your air compressor to clear water from your sprinkler system for the winter. Just be aware that even the largest home compressor isn't powerful enough to blow out the entire system at once. But you can probably blow it out zone by zone.
If you're into number crunching and you have the original irrigation layout showing the gallons per minute (gpm) of each sprinkler head, just divide the total gpm of each zone by 7.5. That'll give you the cubic feet per minute (cfm) you need to blow it out. Otherwise, just rent a 10-cfm compressor and hose from your local tool rental center.
Set the compressor air pressure regulator to a maximum of 80 psi for rigid PVC pipe systems, or 50 psi for flexible black polyethylene pipe. Then turn off the water supply and set the system timer to open just one zone. Next, open the manual drain valve at the end of that zone (if equipped). Then, connect the air line to the blow-out port as shown. Connect the other end of the air hose to the compressor and blow out the line. The heads should pop up and spit out water. Disconnect the hose as soon as they run dry. Don't overdo the blowout—without water cooling the plastic gears, they can melt in less than a minute. So move on to the next zone and allow the heads to cool. Then go back and blow out each zone a second time.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.