Freeze Protection' at 50 Degrees (F) Implemented

Tonight I completed integrating my Rachio Iro Gen 2 unit with my automation system. Using my telephone, PC or smartphone I can now set 50 degrees F (or any other temperature) for my Iro2 shift over to ‘Freeze’ mode. While the Iro2 is in Freeze mode the soil saturation characteristics continue to be maintained but no water comes out…

I implemented this by placing a set of NC (normally closed) relay contacts from the automation system across the Iro2’s ‘Rain’ sensor contacts. I also added an outside temp sensor to the automation system with a variable ‘freeze’ point of anything I want to specify.

I’m starting at 50 F, not knowing how much water is needed at colder temps. If I see things drying out too much (Dallas climate doesn’t get much colder than 49 degrees F on a rolling 30 day basis) I can lower this number as needed (i.e. 45 degrees F).

This is all applicable for running the Iro2 in full automatic mode (Flex Daily), where otherwise freeze protection is dependent on weather station accuracy.

Best regards,


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Thanks for sharing your integration @a0128958! Can I ask what your automation system is that you are using with the Rachio?

Certainly. I use an industry standard burglary / fire protection / automation unit manufactured by HAI (Home Automation Inc) for a long time and now bought out by Leviton. My unit is for large homes or small commercial sites - look up Leviton OmniPro II.

It offers hardwire control of anything, such as the contacts on the Iro2. It also supports connection of temperature sensors. And it supports custom written IF-THEN-ELSE automation logic. In my case, after connecting an OmniProII NC (Normally Closed) output port to the Iro2’s Rain sensor terminals, and installing an outside temp sensor to the OmniProII, I configured the OmniProII to set an alarm if temp goes below 50 degrees, and wrote a couple of line of logic:

IF Outside Temp is In Alarm THEN Turn On Output Port (Opens up the circuit)

IF Outside Temp is Secure THEN Turn Off Output port (Closes up the circuit)

The OmniProII supports changing the 50 degree configuration setting via a telephone (on or off premises), computer (local or remote), or at the console.

Hope this helps.

Best regards,


Hi Bill,

Thanks for sharing that, I’ll have to take a look at the OmniPro per your suggestion. This is a very creative way to make a custom built freeze sensor for sure! Did you have to turn on the rain sensor in the Rachio app in order to get it to work? I assume when the temperature reaches 50 F, the Rachio app then tells you that a rain sensor was activated, and prevents your schedules from running. Is that correct?

All correct.

Remember this is with the Iro2 in full automatic mode (you call it ‘Flex Daily’). And only one (not multiple) schedules. And with connection to a good weather station just down the street.

My single schedule calls for watering each zone as the zone’s moisture level is managed by my Iro2. Each day at 10 AM zero, one or more zones are watered.

I’m connected to Iro2 terminals S1 and SC. Yes, I had to configure the Iro2 to have a rain sensor attached.

Yes, when running automatic, the Iro2 checks 15 minutes before execution time (each day) for an open circuit between S1 and SC. If so, yes, it says a rain sensor is doing it’s job (we all know it’s really the freeze sensor), and no water will flow.

Best regards,


OK, testing has started.

This morning the low was 44 degrees F ( - Dallas weather).

My Iro2 issued a Device Update “Rain sensor activated.” statement today at 1:52 AM. This means it was 50 degrees F at 1:52 AM.

Later this morning, at 8:49 AM, my Iro2 issued another Device Update “Rain sensor deactivated.” statement. This means is was back up to 50 degrees F at this time.

My ‘Flex Daily’ automated schedule is set to run at 10:15 AM any day.

Rachio cloud processing occurs 65 minutes before schedule start. It does a bunch of algorithmic processing at this moment, including:

First looking at:

  1. Is the Iro2’s Rain Sensor option turned on, and if so, is the connection opened up between Iro2 terminals S1 and SC? (Here’s where I have my customized ‘freeze’ sensor connected.)

If the answer to these two questions is ‘yes’ then the upcoming schedule iteration is canceled. If the answer to either question is ‘no’ then processing proceeds further, using the ‘connected’ weather station:

  1. Is it raining now?
  2. Is it 32 degrees or less right now?
  3. Is the forecast to have X or more inches of rain today (I don’t know what X is)

If the answers to any of these 3 questions is ‘yes,’ then again the upcoming schedule iteration is canceled.

What this means for me is that if my ‘freeze sensor’ is not ‘off’ (connection between S1 and SC not closed) before 9:10 AM, 65 minutes before Rachio cloud processing begins, my schedule is skipped for the day (no watering).

What this also means for me is that zone moisture content accumulation continues. Thus if my freeze sensor gets in the way of a day’s watering, the watering amounts will be automatically adjusted for the next day.

So what happened today, just a few minutes ago? In the Schedule Updates section Rachio cloud processing just posted, right on time at 9:10 AM: “3309 Schedule with Zones 10, 3, 7, 6 scheduled to run at 10:15 AM” Perfect!

Yippee! I think this custom ‘variable temp setting’ freeze sensor implementation is going to work!

What I really like about this is that I can absolutely be sure my Iro2 will never water during freezing conditions, regardless of choosing the wrong weather station to connect to, weather station problems itself, etc. My municipality fines heavily for watering during freezing conditions.

Best regards,


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Thanks for sharing your experience and the intriguing read Bill!

All of us here at Rachio are always very excited to hear from our power users as to how they’re innovating with Rachio and their custom solutions. I’m happy to hear how well your setup is working out, and look forward to hearing more!

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Mitchell, thank you for the nice compliment.

For those that live in CO, they’re getting a good deal having opportunity to work for your company.

Best regards,


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Couldn’t this be done using IFTTT with no additional hardware or cost?

Don’t know.

In my case I have implemented freeze protection:

  1. using local temperature right at my residence.
  2. that’s set for something other than 32 degrees F
  3. that works for those running in ‘flex daily’ mode.
  4. that allows for an adjustable threshold (mine’s set at 50 degrees F currently)
  5. that is not based on a WiFi connection (I’m specifically opening or closing a connection between Sensor terminals S1 and SC
  6. that is sufficiently fail safe enough to ensure I absolutely do not water during freeze conditions.

My implementation is a h/w solution (I’m a h/w electrical engineering type guy). Maybe someone smarter than me can determine if IFTTTTTTTTT is a no cost just as capable or better solution.

Best regards,


I did this by connecting the rachio to ifttt and setting a weather underground trigger to set a one day rain delay. For California’s more drought tolerant foliage it saves a bit of water. I’ve had it disabled for a while as I’ve been repairing sprinklers and establishing new lawn.

Cool. For those who run their Iro2 exclusively on full automation ('Flex Daily) this satisfies the desire to use something other than 32 degrees for freeze protection.

Thank you and best regards,


Today’s been a good test day while Dallas area ambient temps are falling fast.

Rachio log messages:

At 9:09 AM this morning: ‘Rain sensor activated’ (Rain sensor terminals S1 and S2 are now closed) (I got a log message from my automation system confirming time)

At 9:10 AM this morning: 'Schedule w/ Zones 10, 7 8 scheduled to run at 10:15 AM (I think this comes from Rachio cloud processing. This is the standard one-hour-in-advance process to determine what the plan (schedule) will be. It looks like Rachio cloud processing doesn’t know that Rain Sensor terminals S1 and SC are closed.)

At 10:14 AM this morning: ‘Schedule skipped due to activated rain sensor’. (This makes sense - scheduled start time is 10:15 AM. One minute in advance the Iro2 cancels the schedule).

Looks good!

Best regards,


Month later update: my freeze protection for a Flex Daily schedule is working fabulously.

I settled in to setting my freeze protection at 45 degrees F. At this setting, combined with Dallas weather lately (cold) (red line)

my single and fully Flex Daily schedule hasn’t watered since mid-Dec.: (blue line)

At this point some zones are ‘bottomed out’ at the ‘Allowed Depletion’ level and thus I’m actually saving water beyond what the Flex Daily algorithms would call for using at this time of year (.01 - .03 Crop Evapotranspiration per day per zone).

It’s warmed up to the 60s now, here in Dallas, during the days, but, the cold at night is still enough to keep temps below 45 degrees up to 9:15 AM, when my Flex Daily processing occurs to set the schedule for the day.

The key things I really like:

  1. By using an attached freeze device directly connected to my Iro2 I’m in control of ensuring that absolutely the Iro2 doesn’t water during freezing temps. No mistakes, no surprises, no dependencies on someone else’s weather station. My municipality fines for creating ice on sidewalks and streets. And my sprinkler system requires a fair amount of repair when I run it during freezing temps (obviously). I am now assured of absolutely avoiding both situations now.

  2. I can continue to use my Iro2 the way it’s advertised (automatic), without having to make any exception for cold Winter months. My desire for the Iro2 is ‘set and forget’ - take advantage of its intended fully automated capabilities. This is the way Flex Daily is supposed to work.

  3. Moisture integration tracking per zone is maintained continuously updated through freeze periods.

  4. (And for me using my smart home, I can ‘set the dial’ at something other than 32, 37 or 39 degrees F - in my case I’ve settled in using 45 degrees. At anything less and I’m now assured that it won’t water.)

Best regards,


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