Rainbird SMT Weather Sensor, Gen 3 controller and Flex Daily

I know my old ESP-SMT weather sensor will not communicate the ambient weather info it gathers to the Gen3 controller. However I’m wondering if I can use it as JUST a rain sensor. Anyone have luck with this? I’ve had my Gen3 installed for a month now with a Flex Daily schedule and it has been doing it’s job with regards to weather adjustments up until today.

I had an issue this morning with a early morning rainstorm (0.26in between 0230-0400 this morning). I had thought the weather plus settings (skip watering with 0.125in of rain) would skip this morning’s watering. The schedule shows that watering was going to start at 0214AM, forecasts (weather underground) showed expected rainfall overnight (~0.3in). The storm was loud enough to wake me up, so I checked the system and it was in the middle of a watering cycle that I had to stop manually. Had I not woken up the system would have run through it’s scheduled watering cycle regardless of the on-going storm.

Based on this, I was hoping to use the old ESP-SMT as only a rain sensor to cover this use case. I’m assuming that the logic adjustments for weather happened in a small window where it did not adjust based on my rain skip settings in weather plus? An attached rain sensor would have stopped the watering cycle autonomously in this case correct?

Is my understanding of Rain Skip flawed? Does Flex Daily not take that setting into account? Moisture balance for the Zones running in the cycle show about 25% moisture balance prior to running, so I understand why the system would water those zones, but the forecast showing rain should have rescheduled/skipped this cycle correct?

Couple things at play here I think…

First, Rachio doesn’t use WU for forecasting, so I’m not sure how the .3" forecasted compared to what Rachio’s forecasting service predicted…

Second, if that forecasted was below the threshold, AND the actual rainfall 1 hour prior to schedule start (that’s when Flex Daily checks), showed zero, then the schedule would have run. It is possible that the rain didn’t start until after this point.

Yes Flex Daily takes the rain skip into play, but I would tend to argue that .125" for the threshold is a bit low. If you look at your moisture charts to see what each irrigation run is expecting to put down, I guarantee every one of them is AT LEAST double, if not triple that. So, if you skip every time there is only .125", you may be depriving your yard of the needed water, especially if you are prone to frequent small rain showers.

The only way that you can use the rain sensor from your current set up is if it has a wired sensor that could be hooked to Rachio. Without spending the time scanning through the 88 page manual for that system, I can’t tell if it is wired or wireless, or how it sends info.

Another thing to check, are you using Weather Inteligence +, or do you have Rachio pointed to a local PWS? It is highly recommended that if you have a functioning PWS near you, that it is a better alternative to WI+. You can click on the PWS to see the history for temps, rain, etc.

1 Like

Thanks for the reply. From what I see, Rachio only displays % chance for rainfall not a forecasted amount of rain so I cannot compare between the forecasting sources. The rain for sure started about 30 minutes after the start of the cycle based on the info from my local PWS. So if there is a discrepancy between Rachio’s forecast and what actually happened then yes I can understand why it decided to run the cycle.

As far as the low threshold, over the course of the last month or so it has been working fine for my yard. Based on my lawn’s appearance and how much stress it is displaying the 0.125in threshold has worked so far during this month with the schedule laid out by Flex Daily. We’re in drought conditions so there is water bans and time restrictions in place. With all that going on I’m okay with how my lawn is fairing currently.

The sensor is a wired one. Two leads into the old ESP-SMT controller, one red lead and one white lead. It seems to communicate ambient temp, rain amounts and wind to the controller, but I don’t care about that data. The rain gauge feature also doubles as a rain sensor, which is what I want to try and use. If I can get it to work then this narrow use case I experienced could be addressed.

For WI+ I’m pointed at a neighbor’s high end PWS they have mounted on a mast on the roof of their home. It is how I’m getting the timing and actual vs forecasted rain fall data.

If you look at the moisture charts, you can see the forecasted amounts.

You should be able to use it, I think…I might have to refer to some of the other resident wiring experts, since this one isn’t technically supported that I can find…but I believe the red would go to S1, and the white would go to 24vac-. Then it would be a matter of telling Rachio what type of sensor is wired in. Hopefully, that sensor works like a traditional rain sensor, and the other sensors don’t cause a problem, but I’m not sure I would hold my breath.

Again, thank you for the reply. I just went and tried it and it doesn’t seem to trip the controller. I can hear the rain gauge working with water moving through the catch cup but it doesn’t register anything at the controller. To confirm I just pulled a wire off the controller and it tripped right away. So I’ve since disabled the S1 terminal and pulled the wires off the controller. Now I just have to think if I really need a rain sensor or if this is something where I would just manually tell the controller to skip if I think rain will come in the early morning hours.

With Rachio, the rain sensor has nothing to do with “thinking” rain will come – that is all from forecast data. If the rain sensor activates, the Rachio will not do scheduled runs until it deactivates.

I use Flex Daily, so for me the rain sensor is just a backup system that makes me feel better, especially when we get into super-saturated situations as it will normally stay activated a little longer.

So no, it’s not really necessary.

1 Like

Thanks for the reply. I was talking more of myself thinking rain would be coming in the small window where the Rachio forecast may not adjust. It seems this is such a small use case in my situation. Based on that I agree, probably not necessary. If I’m wary of the system not adjusting, I can manually skip it the night before, which is a lot easier since I can do that from the app.