How to install 2 Iro's - moving from an old 18 zone controller?

I have an 18 zone old controller box with 2 common wires, no master wire and no sensor wires. I see there is also no electrical outlet to plug in the 2 Iro’s…as the AC is hardwired into the current controller box. I have purchased (1) 16 zone Iro and (1) 8 zone Iro to replace my old controller.

My questions…what do you recommend?

  1. assume I will need to install a normal AC wall socket to plug in the two Iros. I see there are 110v electrical wires on the bottom left of the current box going into a 24v integrated transformer. Please confirm.
    2 ) there are two white common wires going into the old control box, how should these be hooked up into the 16 and 8 new Iros?
  2. the are18 multicolor zone wires going into the old control box, how should these be hooked up into the 16 and 8 new Iros?


@prob, good afternoon, thanks for reaching out. Great questions! I’ll answer them below:

First off, could we combine any of the 18 zones together into bundles of two? If you have small zones with the same zone attributes (vegetation, soil, nozzle, sun/shade, & slope), we might not need to setup two controllers; i.e. if you have 4 drip zones, we could combine them into 2 zones and fit all of your wiring into a 16 zone Iro. If that isn’t possible, please see notes below:

Correct. Will you be installing your Iros indoors or outdoors?

We’ll need to split the zones with their related common wire. Therefore you might have 12 zones on the 16 zone Iro and 6 zones on the 8 zone Iro. You cannot cross wire the commons between the two Iros. This is why I’m hoping we can combine four zones into two zones and eliminate the need for the second Iro.

Please see #2 (above).

Hope this helps :smile:

Best, Emil

@emil why cant you cross the common wires coming in? I did and it seems to work just fine, I had 5 white wires coming in that i bundled together and cut for small wires wire nutted them together then when to all 4 ports for common on the iro. is this incorrect? I was under the impression this was similar to a ground and they should all be tied together

@hosue, can you post a photo of your wiring? I’d like to have a better understanding of what you did. Before and after photos of the wiring would be awesome :smile:

The common wire is kind of like a negative. It is called common because it is common to all of the valves. Each valve in your system can share the common wire, but each must have its’ own individual hot (colored) wire. As such, my recommendation was intended to make sure you kept the common with it’s respective hot wire. Splicing them together below the Iro and sharing between the two Iros (which is what I believe you did) is different than splitting the commons between the two Iros without a splice. Sorry for any confusion.

Since I do not have a master valve can I use the master wire for another purpose?

Yes and no, what did you want to use it for? I have thought about using it to power a led to let me know when it is running. Just because my drip runs for a long time and you can’t hear it. But I have done nothing with this yet as I’m lazy

Can I make a recommendation? Since you have 2 iro’s and rachio hierarchically organizes the zones my controller and not account, you can potentially have a situation where both iro’s will fun at the same time, unless you have the water pressure to do this, I recommend setting the schedules for each iro to run at different days. You have a man’s size cluster of valves there so I’m sure you have an overwhelming number of options.

I’m sorry if this has already been stated or if I have insulted your intelligence with this post.

You can do this for a single iro, what @emil was referring to is bridging the same common into multiple iro’s. Depending on how they ground the electricity coming back from the valves, when pushing voltage to the iro not powering the valves, damage could occur. Staying away from all the techno garble that I’m not very strong in. One thing you could do though is use the master on iro a to power a solenoid switch that would connect the ground to iro a, which has a rest state grounded to iro b.

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How does the master valve switch differ from other off/on switches? Why could it not be recruited to perform a different function such as open a valve to fill a swimming pool as a part of an irrigation schedule?

Because the master valve is a global operation. If enabled, it will always open when any zone runs. If you want to fill your pool every time you run a zone, sure.

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Good explanation. Thank you

Thanks @plainsane for helping to explain. We’ve had a few users experiment with wiring up one valve across two Iros with luck using a relay. Here’s a support article that explains the details. Given the title of this topic, I hope this helps any other users in the same boat.

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Yes a relay would be better

the support article for sharing common wires is no longer available. Can you repost the current link?

@Simonite - I think this is the updated article ->

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