Connecting New Iro in parallel with existing controller

I was wanting to connect a new Iro to try it out in parallel with my existing system (where only one controller would be active at a time). In the manual, it pointed me to which lands me on this page regarding two Iros managing a single master:

Seems like in my case, I would need to use the same 24VAC switching for each zone in addition to the master valve correct? I can see why electrical code would not count software scheduling as a valid control to prevent two controllers from applying two AC voltages at the same time.

In my case, if only one controller’s power supply was plugged in at a time, all will be well?

What I am doing is running my rachio on the desktop (actually, on a table in the living room)… not connected to any sprinkler wiring. I just set it up, programmed all my zones, etc. It doesn’t know it isn’t actually wired up to the zones. Gives me a comfort level for a few weeks/months then I will switch it out.

Much easier, no extra wiring, no risk to either controller.

Thanks. That’s what I’ve been doing so far. Currently, there are two areas that are must haves to use it in the desired flex timing mode. It would be nice to pre-wire it with one system disabled since I believe it will eventually handle my needs. Plus, my city allows for some watering flexibility based on the current controller and ET system so I’d like to have it installed in case of inspection.

I was just wanting to confirm the electrical isolation requirements for a parallel installation.

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Just let us know if you have any questions regarding scheduling. For our Spring release we are revisting flex and fixed and will be merging them together. Fixed will stay the same, flex will be ‘water as needed’, set to a different interval each month automatically, while skipping some intervals if the schedule can make it to the next interval based on forecast and current zone moisture level. It will be simpler to understand and less question as to when it will run next, while getting the benefits of automatic monthly adjustments.

Hope this helps.


If I were wiring in parallel (heck, I might as next step), I would switch the common out to the zones w/ a Single Pole Double Throw switch.

Old Controller  Common --------
                             SPDT  Switch ------------  Zone Common
New Controller Common ----------

Switch the common to the appropriate controller and unplug the other one.

The primary issue I’ve had are that there are not enough soak cycles for clay on a steep slope so I would get tons of runoff in the flex mode even in the peak of summer if the soil was dry. Currently to use my 0.4"/hr MP rotators and absorb the targeted 1" of water, I need to break my cycles up quite a bit…much more than the Iro currently automatically accounts for.

But other than that, any intelligence to monthly scheduled watering times scaling sounds like a good addition.

Only other issue I’ve ran into is for handling a tree bubbler. Impossible with Flex. My tree is bowl shaped and optimally filled and cycle\soaked several times to get down to the roots. I was able to get the expected scheduling through multiple regular schedules manually spaced for soak.

The rest of the scheduling looked pretty good and I suspect would result in fairly optimal efficient watering.

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