whattheheck,

sorry couldn't help myself. How many zones on the controller and how many auto valve(solenoids) in the two boxes? If there are extras it will be evident with the comparison. Manually turn on the zones(turn the solenoids counter clockwise slightly until zones are on, Clockwise to turn off, do not over tighten, just enough to shut off irrigation). Are there any obvious area that need irrigation? Does the mainline that feeds the valves in the two existing boxes go beyond the two boxes and into the yard? Aloha

Eleven zones on the controller. One is not being used. We can account for 8 solenoids/valves. The area of the yard that is not being irrigated is the area where we suspect there's another box. We've dug around whereever there's unplanted ground but haven't been able to find it. The mainline goes into the yard.

hb,

Make a thin metal probe that can be easily pushed into the soil. Some landscape store have it, but you can make your own with a handle on top to help you push it down and up again. Follow the mainline by probing and striking (softly) the mainline. It should be fairly close to the other boxes. Check if there is more than one mainline from the source(teed off). Is the irrigation on a hose bib or directly from the hose mainline? Try this also. Manually turn on the two unaccounted for zones and listen on the mainline with your ear on your fist on the probe. Listen for water movement noise. Using the probe in this manner and follow the mainline and noise. If there is noise you will eventually hit a very soft spot where the leak is and probably the box. GL JMHO Aloha

Thanks--we will try this. We suspect that the problem is electrical because last week we had a problem with a solenoid in one of the boxes and, as soon as we replaced it and the emitters it controls started working, the emitters somewhere else stopped working. Too bad the people who put in the system didn't leave us a map!

hb,

Recheck the wiring of your controller and make sure all terminations are secured. Record the terminal numbers with a sketch of your irrigation zones. Doing this will make sure of no crossovers or just because it helps you understand your system. Also check all solenoid wire connections in the boxes as being snug. Aloha

I teach electronics to middle school students and the best way to find buried valves is to make a valve 'clicker' I make one whenever I need it.
A valve 'clicker' will move the solenoid plunger up and down rapidly and you can listen for the very distinctive noise...Click,click,click.
E-mail me at pumpsys@embarqmail.com if you need more information.

Here is a link that might be useful: P2FlowLLC