Rainbird ESP-TM2 to Rachio 3

I’ll be replacing my Rainbird ESP-TM2 with a Rachio 3 this weekend and had a few questions about the wiring. The numbered wires are obvious and I understand the C wire can be plugged into any of the C terminals on the Rachio.

  1. I have 2 sensor wires on the Rainbird (SEN and SEN-C), does this mean I have 2 rain sensors?
  2. Is there any particular order I would connect the 2 sensor wires to the Rachio’s S1 and S2 terminals? I am aware that I can probably do without these since the Rachio has weather intelligence but I’d like to connect them anyway if it’s not complicated.
  3. There are two 24VAC wires (HOT and COM) on the Rainbird - I read that these are not needed on the Rachio since it comes with its own power adapter. Is it possible to use these wires to power the Rachio instead of the power adapter?

1 & 2) No, I believe that would be a sensor power, and sensor common wire. If you want to keep it, we’d probably want to confirm the model of the sensor. Some hook to Rachio differently…

  1. The 24vac should be how the unit is getting its power and you are correct, not needed with Rachio. Not knowing where or what that power source is, I’d not recommend using it.
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The sensor is a rainbird RSD-BEX. RSDBEX - Rain Sensor - With Bracket.

@xargsgrep - that is installed as a wired sensor.

One wire goes to S1.
The other wire goes to 24 VAC - (common for sensors).

See → How do I install a wired sensor or wired flow meter with Rachio 3?

And then set Sensor 1 in the app to a Rain Sensor.

Ok got it, I think it makes sense now. Thanks.

With the weather intelligence, many find that they do not need a separate rain sensor. Therefore, I usually recommend getting it working without it first. See how it works. You can always add it later.

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I’ll second this recommendation. The two state rain sensors (wet / dry) don’t do much except tell you SOME rain fell recently - although the RSD allows you to dial up what “wet” is. When installed on a Rachio it simply disables watering whenever it’s “wet”. Re-enabling the Rachio requires it to become “dry” which is significantly imprecise. Weather intelligence has excellent data on how much rain has fallen… without your sensor.