Manual-draining sprinkler heads have check valves on them ... from the water main supply and blow out your sprinkler system zone by zone, they should also close the main shut-off valves.

Ok, software done; on to the relay controller box! [danman]’s sprinkler system has four 12V AC valves that need wrangling, and no data cables, necessitating the wireless setup. Initially ...

Leaks, low water pressure, and broken valves are all issues homeowners ... trapped air out by draining the sprinkler system before recharging it one zone at a time. For more complex repairs ...