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ashton allen

Starting Member

1

Monday, May 16th 2016, 5:47pm

Strange Thing Happened

One afternoon, during a hard and steady rain, my zone 4 turned on by itself, while the control was in the off position. We don't have a master shut off, so I turned both handles of the backflow preventer to the off position - perpendicular. Strangely, he zone kept running. I called Nelson, the name brand of my system, and explained the problem. They told me how to short the system to see if that might turn off the sprinkler and it worked.

Today, I ran zone 1 with both handles of backflow in the on position, paralle. Zone 1 ran fine for for the 1 minute test. I turned both handles of the backflow to the perpendicular position "off" and ran the same zone for a 1 minute test. With both handles in off position, the zone didn't run just as you would expect.

So the question is how in the heck did one of the zones turn itself on, then more oddly, how did it keep running even after I turned off the water supply at the backflow preventer. What could account for this?

This post has been edited 1 times, last edit by "ashton allen" (May 16th 2016, 8:47pm)


mrfixit

Moderator

Posts: 2,009

Location: USA

2

Monday, May 16th 2016, 9:18pm

We've had a couple similar mystery questions similar to this. Turns out that there was a second valve attached to the line.
If there had been any modifications to the yard, possibly all new valves with a backflow installed, there's a chance the old valve/s are still hooked up somewhere not associated with the backflow you shut off.

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