Ice, Ice baby

I woke to ice from my sprinklers this morning. Now a smart controller like mine would never allow that right? Wrong.

After a few frustrating hours I have concluded this thing is pretty dumb.

First, I am running in the suggested Flex daily mode. Second, I am 7 miles from DFW airport where I get my data.

The first thing is, I went through one hour trying to find the setting “Weather Intelligence.”

It doesn’t exist on my phone app or online. I search all the documentation…why cant I set my temp?

Turns out that a phone chat (on Sunday!) reveals that isn’t an available setting on flex daily. These settings are…drum roll…pre set! To what I don’t know but wait there’s more!

It also turns out that I have my sprinklers set to run after midnight (its Texas). So the controller consults my set weather station one hour before running THE WHOLE SCHEDULE! One time!

So if its 40 degrees at 11:00 and 25 at 4:00 am, your “smart” controller will just keep on watering!

And of course it’s my wife that discovers the ice on the okra…I, in a properly hurt sounding fashion say, “no way, my smart controller would never allow that to happen!” Wife rolls eyes and here i am three hours later typing this.

I think the controller HAS to check the weather more frequently ESPECIALLY during the schedule. And the flex daily has to allow the settings changes to compensate for DFW showing 36 as the low last night and i got ice.

Until that I will just stay up all night and monitor the local temperature, wind, rain etc and turn the controller on and off as it makes sense for the weather…when my wife yells…“come to bed” ill say I cant honey, my controller needs me.

(BTW, my deductive reasoning skills lead me to believe that it would gladly water during rain IF the weather was dry when the controller checked an hour before the schedule started, but I might be wrong)

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You’ve stumbled on a serious flaw of the Iro2 when used in full automatic mode (Flex Daily). You really don’t have reliable freeze protection. This protection is provided for by the assumption that the weather linkage will manage it. But as you’ve discovered, there are many caveats to having true, absolutely unfailing freeze protection. In fact, it isn’t possible for those using the Iro2 in full automatic mode.

For now, until Rachio decides to address this, you’ll need a separate means to monitor your outside temperature, at the location of your sprinkler system, and turn off your Iro2.

In my case, since I already have a pretty advanced home automation system, I can use it to interrupt the common wire to all of the valves based on measuring temperature on my back porch. I have my automation system programmed such that for any time outside temp is less than 39 degrees, it opens up the Iro2’s common wire connection to the valves. The Iro2 continues to run along, fat, dumb and happy, but in fact no water/ice gets put out on the street/sidewalk (which in my municipality it’s a ordinance violation and you get a citation).

You may be aware that Rachio announced a new release is coming. But, since Rachio states clearly that it’s a software company not a h/w company, and since the last major change did include h/w changes, my guess is you/we won’t get relief on this serious shortcoming, at least not soon.

For its ‘full automatic’ users, Rachio needs to provide a coupld of terminals that connect to a local freeze sensor. That way, no matter how the Iro2 is programmed, the connected freeze sensor takes over and stops the Iro2 from running.

Best regards,


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ROFL :laughing:

If there is any place a smart controller can’t be dumb, it’s Texas. Our weather is too unpredictable.

My controller behaves different than yours. Here is what it did last night. I checked the weather station that I am connected to and here were the temps last night: 3am - 35.4deg, 4am - 34.3deg and it reached 32 degrees at 5:30am. It ran Zone 4 and finished it at 4:52am but skipped Zones 3 and 6 which would have run after Zone 4. This seems to say that Iro2 checks the temps more than once (?).

This reminds me that I believe the freeze turn off temp, when in flex daily mode, is static at 32 degrees, without opportunity for adjustment (i.e. to 33, 34, 35, etc.)

Also, my work around solution isn’t really very good. While it does ensure absolutely there’s no sprinkling during ice forming temperatures, it messes up all of the ET calculations. Iro2 thinks it actually watered when it really did not. Not until it rains a large amount does reality sync with calculated soil moisture content.

Best regards,


Is it possible you have each zone in a different schedule? That might mean that it’s not one schedule watering all zones, but many different schedules each watering a couple of zones.
That would explain why one zone/schedule (“Front Lawn flex”) watered at 3:14am, yet the other one (“Flex schedule”) that would’ve done zones 3 and 6 skipped. Not because it checked in-between each zone within the same schedule but because it checked between each different schedule.
That would be my guess, and perhaps a potential workaround, albeit clunky. But hey, this way @Lngtrm1 might not get yelled to get back to bed :smiley:

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They are in different schedules.

Hey Bill, thanks for the info,I was unaware of Rachio’s upcoming changes because I thought I already had a smart controller so i wasn’t looking for a “new” one.:slight_smile: )

It seems a simple sw issue to have the station check hourly always and interrupt for rain or freeze. The hard part of course is for the controller to figure out where it left off and resume.

Your fix is wayyy more than I would do to simply sprinkle reliably and sensibly. (How does the controller figure out no water was provided and account for that?)

Thanks again,


The tech I chatted with wasn’t sure what the pre-set was but I have seen this 32 degree number somewhere else. But here’s the problem…most temps are measured at 4-6 feet above the ground because they want “air temp”. But on nights when the sky is clear you get an inversion where cold air gets trapped near the ground, (hence the warnings about frost or freeze in low lying areas). So a 37 degree temp from your local weather station could easily be five degrees off at ground level depending on soil temps winds etc.

So…air temp isn’t ground temp so you would logically provide some user programming as they have in the other modes, just not in flex daily.

I see you covered my earlier point on water amounts…



That’s what the tech suggested, multiple schedules. He suggested an on and off time for each schedule, that I assume wouldn’t overlap .I asked if I could do that for EVERY station and my question was if the controller could figure all that out because five of my zones need cycle soak as I have slopes. The answer was no.

Yes it checks one hour before each SCHEDULE. Reacts accordingly. Short schedules would help a little but I have 12 zones, many on rotors (longer run times). So a 40 minute rotor schedule with cycle soak takes a long time. And of course another schedule can’t use that soak time to water elsewhere.

Given 32 degrees is the wrong setting no matter what, I’d say the work around’s aren’t useful enough to employ.

@a0128958 and @Lngtrm1 - wouldn’t a freeze/temperature sensor attached to a sensor port set as a rain sensor work? Wouldn’t this also prevent the water bank from getting out of whack with reality as the Rachio would know that it didn’t water.

Not sure, I dont know if the system allows outside interrupts physically or in sw to schedules. If it does that properly one has to wonder why they didn’t program it that way for weather info interrupts to schedules.

@Lngtrm1 - yes, Rachio does accept external inputs that can stop the schedule, as in an external rain sensor. The other use for one of the two sensor ports is for a water flow meter to record actual water usage instead of estimated. I’m 99.999% sure that an external normally closed temperature sensor that opens the circuit when the target temperature is reached will signal Rachio to not or stop watering. Ideally, the temperature set point could be adjusted like a rain sensor can be adjusted for the amount of water that takes to trigger it.

I mostly follow your thinking. But is there a physical and sw connection point for a freeze sensor?

@lngtrm1 - As pointed out earlier for the non-Flex Daily schedules one can adjust the temperature setting for a freeze skip in the Rachio user interface - which is what I’ve done on my fixed schedule (FYI, I’m not using Flex due to watering restrictions that would limit Flex’s usability). A hardware based freeze sensor (temperature sensor) would behave just like a hardware based rain sensor, i.e. Rachio would send out a rain sensor tripped notification when the freeze sensor tripped.

Is there an easy freeze sensor I can buy on Amazon that’s compatible?

I’m going to change my Iro2 / Home Auto system interface and learn what behavior changes occur with the Iro2.

Currently my home auto system opens up the Iro2’s common wire to the Iro connected valves when the home auto system reads 39 or less degrees outside temperature. I’m going to instead use the home auto system to directly open or close the Iro2’s rain sensor terminals based on outside temp less than 39 degrees.

I’d like to learn how the Iro2 will behave in full automatic (Flex Daily) mode when exclusively using one Flex Daily schedule (covering all my zones). My FD schedule is set to start daily at 1 AM.

Ideally I’ll observe that the Iro2 does not allow for the schedule to run when the terminals are closed, regardless of how much before, during or after 1 AM it is when outside temp becomes less than 39 degrees. And that soil moisture continues to be accurately tracked.

I’ll report later what I observe.

Best regards,


Rachio publishes an IFTT applet for freeze delay. It’s not fine-grained but might do the trick for some. If today’s low temp is forecast below 32F, the applet will trigger a rain delay for 1 day (or more, your choice.)

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You can also program your own freeze delay with ifttt and weather underground. Maybe set it to skip at 35 degrees and it checks often; not just once per day. I use that in California to water skip below 50 degrees. Don’t need to water in cool temps.