All zones have power at controller

post by kraymondksc on Jun 1, 2021

Hey all, I have an 8 zone gen 2 Rachio. I’ve used it for a few years now without issue. This year after startup, none of the valves turn on. I can manually turn them on.

Here’s the strange thing. When I test the zones with my multimeter at the controller, all zones show about 28 volts when only one zone is on. Out at the zone box, I get no power reading unless I disconnect the solenoids from the irrigation wire and test just the common and a zone wire.

Wondering if anyone could help explain what’s going on so I can try and get to the bottom of this issue. Thanks!

post by NCSuggs on Jun 1, 2021

Sounds like you have a short. Some where underground your insulation has broken down and your copper wires are touching each other.

post by Gene on Jun 1, 2021

The common on Rachio controllers is tied to 24V+ rail, whenever a zone should be active, it’s corresponding output is “grounded” to 24V- rail. If you are measuring to 24V- rail, rather than the common, then you’ll see the common voltage (24V+) on the inactive outputs.

Do you have a rain / freeze sensor in line with your system? Prior to smart controllers, the rain / freeze sensors would physically disconnect the common from the field wiring, thus preventing unneeded watering.

post by kraymondksc on Jun 2, 2021

Thanks all for the replies. I suspected a short. I’ll try hunting it down.

Gene, there was a rain sensor at one point but it looks like the previous owner cut the wires that run to it. It’s hanging on the side of the house but has been disconnected since I moved in. Also, I’m trying to understand what the 24V- rail would be. I just tested from the common input to each of the zones. Luckily my neighbor also has a Rachio and I was able to verify on his that only the active zone was outputting 24V+ when measuring the same way.

post by Jgreenb2 on Sep 27, 2023

@Gene I know this is an old thread but your hint about the rain sensor just saved me a lot of grief. We had a very old rain sensor in our gutter that hadn’t been used in well over a decade. It wasn’t used by the rain-bird controller in the house when we moved in and it wasn’t used by the Rachio 3 that replaced it. It was in my way so the last time I cleaned that gutter – about 2 weeks ago – I removed it by simply cutting the two-wire strand. Had no idea my common was running through that thing.

Anyway, thanks for helping out!