MIght be that the controller (a computer after all) had a brain fart and you reset it by doing a power off-on reset. Also could be the zone 1 solenoid valve is getting "sticky" or the spring in it is wearing out or it caught a piece of crud in it that held it open a bit. Zone valves are in the ground outside usually in a in-ground box not far from the controller (to keep the wiring run short)covered by a plastic lid. They're "pulled open" by the electromagnetic field that overcomes a spring. When the power is applied by the controller, the resultant EM field "pulls" it open overcoming the spring pressure that's holding it shut. When power is cut off (controller command zone 'x' off), the EM field goes away due to no electricity and the spring takes over and shuts the valve. Maybe just a piece of crud got in there and cleared, but keep an eye on it. If it keeps doing it, you're going to need to replace that solenoid valve or there's a problem in your controller (any close lightning strikes lately?). Just watch it and see if it weren't a few 'trons with the hiccups.

Thanks Chere for the detailed explanation. Here is what I have noticed in the last couple of days -

On Sunday, Only zones 2 and 3 were programmed to come on. However somehow, Zone 1 also got started when zone 2 was on. I had to do the same thing again. Unplug the controller for zone 1 to stop. if I just unplugged and plugged back in, the zone 1 would start again. The key was to keep it unplugged for about 10-15 seconds for it to not start back up again.

So, it looks like the zone was starting even when it was not part of the cycle. And, it would not shut off unless the controller is power cycled.

Given that the valve does indeed come on and shut off (although by brute force of unplugging the controller) as it should, I am thinking that as Chere pointed out that it might be a controller issue.

I thought that it was something to do with the zone 1 circuit on the board and hence took out zone 1 and plugged it into zone 5 which was vacant. Here when I did a test, it worked fine. It did come on and shut off as it was programmed.

Given these additional details, I think something in the rainbird controller esp-6si croaked. I think I will go ahead and do a complete reset of the controller - unplug, remove battery and fuse wait for about 3 min and reprogam.

Anything else Chere and other can think of? As always, your input is very much appreciated.

Thanks,
Ram.

Certainly appears to be a controller problem with what you describe. May just be the controlling circuitry for zone1 is faulty. Since you have a spare and already swapped the wires to that one (5), then you can probably just get away with using zones 2-5 (zone 5 will be the cat formerly known as zone 1). Keep an eye on it to make sure it doesn't degrade further. If the (now) zone 5 begins acting up, then there's a problem in the solenoid valve or wiring to it that's causing a problem in the controller (wrong resistance in the solenoid).

Chere, Saw your reply and wanted to update you about the conversation I had with the rainbird rep. What he said was that there seems to be a voltage bleed between the other zones and zone 1. This happens when the controller is starting to go south. He also said the same thing about the swap and asked me to keep an eye on it too.

It seems to be working fine at 5. I hope I can get away with it for now.

Thanks,
Ram.