Help With 3 White Common Wires 2x Controllers

Rachio Experts,

First, I am not an electrician and can’t speak in ohms and AC; however, with the attached diagram, I hope someone can help me solve why my second 8-zone controller is not activating when the APP says that it is on. I think my problem may be with connecting all of my common wires together. I have a master valve and know that it must be connected to the red wires between two isolators, but the 3 white commons are throwing me for a loop. Help please! I created this powerpoint to show exactly how everything is currently wired.

@VARachiox2 - thanks for the PowerPoint diagram.

I take it that zones 11, 12, 13 and 14 work on the Gen 3 16 terminal unit? Correct?

  1. Is the Master Valve option enabled in the app for the Gen 3 8 terminal unit?

If that isn’t the issue, then what happens when the Master valve wire and all the commons are attached directly to the Gen 3 8 terminal unit? Does a zone there now water?

Welcome to the community!

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Gold star for the PowerPoint!

:cheers:

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Thanks DLane, I’ll be back in front of my system in a few hours and will have more time to switch the wires over to the Gen 3 8 terminal. I can confirm that the M Valve option is enabled on the 8 terminal. Be right back in a few hours. Thank you for your responses.

Thanks Franz!

Ok first, I tried a wire from the 8-zone into the 16-zone controller and the zone worked without issue. Second, I did the opposite and the once working 16-zone wire did not work in the 8-zone controller. Next, I removed the controller from the weather proof box to get at the isolators (see picture). I switched the black and white isolator wires (MV and C) on each controller. The 16-zone continued to work and the 8-zone continued to not work. I think this rules out the isolators as the issue. Next, to determine if the 8-zone is the fault, I took the isolators out of the equation and connected the three white common wires and the MV wire directly to the 8-zone controller — surprisingly, the 8-zone controller worked without an issue. Next I did the same for the 16-zone controller and it also worked as before. I think this rules out my irrigation system being at fault.

The problem I feel like is when the three white common wires are joined together with the isolator white wires. When I do this, the 16-zone works fine, the 8-zone does not. I don’t see this as a hardware issue… it appears to be a dominate system (16-zone) not allowing the 8-zone to function while conjoined.

I don’t know what to do next… thoughts?

Ok first, I tried a wire from the 8-zone into the 16-zone controller and the zone worked without issue. Second, I did the opposite and the once working 16-zone wire did not work in the 8-zone controller. Next, I removed the controller from the weather proof box to get at the isolators (see picture). I switched the black and white isolator wires (MV and C) on each controller. The 16-zone continued to work and the 8-zone continued to not work. I think this rules out the isolators as the issue. Next, to determine if the 8-zone is the fault, I took the isolators out of the equation and connected the three white common wires and the MV wire directly to the 8-zone controller — surprisingly, the 8-zone controller worked without an issue. Next I did the same for the 16-zone controller and it also worked as before. I think this rules out my irrigation system being at fault.

The problem I feel like is when the three white common wires are joined together with the isolator white wires. When I do this, the 16-zone works fine, the 8-zone does not. I don’t see this as a hardware issue… it appears to be a dominate system (16-zone) not allowing the 8-zone to function while conjoined.

I don’t know what to do next… thoughts?

images are delayed… i’ll upload asap… you may not need them to answer though. Thank for all of your help!

IMG_2900

@VARachiox2 - assuming that the Isolators are correctly wired (I can’t confirm that via the photo), but they are described as being correctly hooked up, I’m puzzled. I might contact TSM (makers of the Isolator) for support - 530-751-2610.

@Gene - any comments?

However, I do have a solution:

  1. Exchange the 8 terminal Rachio for a 16 terminal Rachio.
  2. Move all the dotted and dashed lines to the new 16 terminal Rachio, including their respective white common wires.
  3. Acquire a 24VAC DPST relay like:
    https://www.amazon.com/Relay-24V-SPDT-NO-NC/dp/B009AXJQ3A/ref=sr_1_4?keywords=24vac+spdt+relay&qid=1562548245&s=gateway&sr=8-4

a. Hook the common/pole terminal on the relay to the wire going to the master valve in the field.
b. Hook the NC terminal on the relay to the M terminal on the original 16 terminal Rachio.
c. Hook the NO terminal on the relay to the 24 +VAC terminal on the original 16 terminal Rachio.
d. Hook one of the relay coil terminal to the M terminal on the second/new 16 terminal Rachio.
e. Hook the remaining relay coil terminal to the C terminal on the second/new 16 terminal Rachio.

There are no shared commons in this setup. With the relay in the NC position, the M power from the first Rachio will power the master valve. When the second Rachio fires, it will close the relay and provide power from the first Rachio’s constant 24 +VAC terminal to open the master valve. The relay coil is powered by the second Rachio only and there is no cross connect.

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I really dislike these “ISOLATORS”, a better isolation can be achieved with one double pole relay like this $8 relay from amazon (link), more on such setup here (link). @DLane has outlined the steps for such a setup with a similar relay (exact relay does not matter for this setup). One thing to note is that NO terminal should be connected to 24 -VAC terminal in step C of @DLane’s post, this is counter intuitive to how things are normally done so…

Back to the topic at hand. Try connecting the black (input) wires from each of the isolator to the M terminal of the controller nearest that isolator, then connect the red (output) wire out of each isolator together with each other and the MV wire going out to the field, finally hook up all of the white commons (four from your isolators, two from both of your controllers and one from the field wiring) together and see if your system is now working.

Edit: Just noticed that you’ve actually started this tread with a nice diagram of your setup. The problem is that these “Isolators” will also disconnect the common so the controllers will not be able to water anything at the same time. Here is an updated diagram to help you better understand what needs to be done:

Cheers,
Gene

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Gene,

I’m very happy to tell you that the added white common wires did the trick! I needed to connect the two ‘unnecessary’ white wires coming from the isolators together in order to get everything running perfectly. Now the only issue is that I have a zone that goes up and will not come back down… assume it is the solenoid and will replace if necessary. Thanks to you, I am not giving up on Rachio! way to save the day…!!

Best,
Jeff

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DLane,

Thank you for all of your thoughtful support. I’m sure the 24v relay would have did the trick, but as you can see by my conversation with Gene, it was a simple solution. I recommend this thread for anyone dealing with 2 controllers and 3 common wires. I’m surprised this wasn’t already talked about and troubleshot?! Regardless, I hope someone else can now benefit from our conversation and solution.

Best,
Jeff

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Thanks for providing the feedback on the “unnecessary” commons, useful feedback like yours is what helps this community get stronger :wink:

Glad everything is working for you. You are right that a zone failing to stop sounds like an issue with solenoid, hope it will turn out to be an easy fix. :+1:

Cheers,
Gene

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Gene,

I spoke with TSM about the solution using the white common wires. They are concerned that we are not ‘isolating’ the field commons between the two controllers and only isolating the MV field wire. They said it may cause the same problems that we were trying to avoid in the first place. Do you feel like we are isolated against a possible situation where both controllers call for a zone to operate and possibly fry the controller? Of course worse case, but bad nonetheless. Thoughts?

Thanks again

As long as only the common is shared, there should not be any issues.
Sharing a second signal (such as MV) would create a second point of contact which may cause an issue.

None of your zones are shared, each individual zone is connected to one controller or another (MV is isolated).

Rachio is using a 24VAC transformers within their power supply, these provide isolation from the mains, you may want to be cautious in case you ever try to use a 3rd party power supply.

For your sake of mind, feel free to disconnect the two new commons from the main wire nut (return the two controllers to be completely isolated), get a multimeter and measure AC current between the commons of the two controllers. Reading should be close to 0 (few uA is ok).

In reality, in case there was an issue with your current setup due to power flowing via common from one controller to another, you would have noticed it right away. Common wire would get hot and units would not work well.

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@VARachiox2- Did TSM give any input as to why their product didn’t work in the previous configuration?

If you’re really concerned about it, then the relay and a larger Rachio will be completely isolated from one another.

@Gene - thanks for piping in. You’re much more up on the nitty, gritty electrical than I am.

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DLane,

Sorry for the late response. No, TSM were very helpful and full of ideas, but didn’t want to discuss why their isolators might be acting this way. I’ve left the configuration that @Gene recommended and everything is working without issue. I’ve even replaced the faulty solenoid and now have a 100% functioning system… knock on wood :slight_smile:

Thanks for your help again!
Jeff

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