Temperature sensors for freezers

I know this topic has been discussed before, but all of the threads relating to it that I’ve been able to find are pretty old, so I was hoping there might have been some developments in the area that my Google Fu has been too weak to unearth.

So…does anyone know of at least one good off-the-shelf ST compatible temperature sensor that:

  • Has an operating temperature range that extends below 0°C/32°F.
  • Can reliably transmit from inside of a freezer (I’d prefer to avoid closing the door on a sensor wire if I can help it).
  • Has a reasonable (yes, that’s quite subjective) battery life at freezer temperatures.

I know that RF from inside a metal box like a freezer can be problematic, but I’ve seen several people cite examples of sensors that have done it. And while my hub is about 30 feet away on a different floor (with a couple of walls in between as well), I have multiple repeater-capable Z-Wave and Zigbee devices spread out between them. Combo units with open/close sensing would be nice, but that functionality isn’t an absolute requirement.

So, let’s go the phones. Hello, Albuquerque…you’re on the air.

I use an Everspring ST814 without any issue. I have to say though my hub is directly behind my freezer with 1 wall in between. Battery life? Not sure anymore. It used to be “bad” (3+ months) when I configured it (via device handler) to report RH and temp every 1 minute. That did not bother me as it uses AA batteries which I get on the cheap at Costco.

On a side note. I placed the same device inside my garage which I think must be encased in sheet metal. While most of my z-wave/zigbee do not play nice here the ST814 worked fine all winter.

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Do you get freezer-level temp readings from it? The unit’s specs say the operating range is 50° to 122°F (10° to 50°C).

Considering how well insulated the freezer is, and the fact that I have a mechanical thermometer in it already that I glance at whenever I open the door, I don’t think I’d really need reports more frequently than 1 per hour or so, so I could probably get much better battery life than that.

In any event, thanks for the feedback. I’ll look into it.

Lots of people doing this. See the following thread ( in which I was famously incorrect to begin with :stuck_out_tongue_winking_eye: )

[quote=“JDRoberts, post:4, topic:48124”]
Lots of people doing this. See the following thread ( in which I was famously incorrect to begin with :stuck_out_tongue_winking_eye: )[/quote]

Yeah, that’s one of the older threads I found. It contains some possibilities, but nothing certain. By that I mean things like, for instance, the fact that the specs for the ST MP sensor indicate an operating temp range of 32 to 104°F (0 to 40°C)…which might be OK, but I’m not sure given that my freezer tends to run slightly below 0°C. And most of the other solutions weren’t really off-the-shelf. But I’ll go back over it and see if I missed something more ideal.

ETA: I already see that I somehow managed to miss the Everspring ST814 reference at the bottom of that thread.

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Check out Wireless Sensor Tags.

Now that’s interesting…

I use 6 of the Iris open/close sensors inside 3 frig/freezers in my home. My frigs average in the low 30’s, and 2 freezers are at -2F, the other is at -21F.

These have been very reliable, and the device handler allows for a temperature offset (if needed). All 6 are inside the frig/freezer, and I get the benefit of knowing open/close state and temperature. I bought these as soon as these hit the shelves at my local Lowes, so somewhere around Aug/Sept 2015. These are frequently used, and my battery levels are averaging 55%. Pretty darn good bang for the buck if you ask me.


I really like these devices and Swanny has made a nice integration for them with smartthings, and you can also use them with their IFTTT channel. But it means adding yet another protocol and yet another bridge to your system. That will be fine with some people and out of spec for others so it just depends on your individual preferences.

Where did you find those specs? It has a feature called freezing point alarm. Anyway… The spec I found states
Operating Temperature Range -10℃ ~ 50℃

My freezer is running on average -13C. This unit has been inside for nearly 6 months and sending me updates without fail :wink:

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If I had to guess I’d say that was an error that caused the minus sign to be dropped in the SmartHome version of the specs.

And that’s exactly the kind of real-world results info I’m looking for. Thanks again.

I’ve had WST’s in my freezer, fridge, and attic for over two years, all on the initial batteries. Temps in these range from -10F to 130F.

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Well, after over a month of consideration…and mostly just being distracted by every day life in general (including a FL beach vacation)…I finally got around to ordering an Ethernet Tag Manager and one unit of the “rain proof” version of the WST Pro 2.0 so I can give this whole freezer monitoring thing a try. They should be in my grubby hands 3-5 days from now, so here’s hoping for the best.

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I’m using a standard, non-rainproof Motion w/13b Temp/RH in my deep freezer. I’ve seen it get to -11F without any issues. It’s been there for a month and is down to 88% battery. My hub is also in the garage with the deep freezer, so the signal is pretty good. I do leave it disarmed and tell it to check in every hour to reduce battery usage, but it does eat up the battery still. For what it is used for, I can justify buying new batteries more often than the others.

Something that might be helpful if you don’t care about the internal humidity, try vacuum sealing it. That will keep the moisture out of the device and keep that moisture from freezing on the components.

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That’s a good idea…and I’m embarrased that I didn’t think of it myself, given that one of my favorite new gadgets is the vacuum sealer I bought a couple months ago.

How do you think I came up with the idea? :slight_smile: I am working on doing the same thing for a mailbox sensor. Cheap sensor, vacuum sealed.

I’ve read all about the company’s poor post-sales customer service, but haven’t yet found any complaints about the ordering or shipping. I’m bringing this up because I ordered these goodies last Friday (6/24). My PayPal transaction was processed the same day, and I immediately received an e-mail indicating that my order was being prepared. According to their website they ship all orders within 3 business days of receipt of order. But here it is nearly a week later and the status of the order hasn’t changed from “We’ve accepted your order, and we’re getting it ready.”

For those who have ordered from them before, is this normal?

I’ve ordered from them twice without issue. I had both orders in hand within a week of ordering.

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Thanks for the feedback.

This is how I measure my soil temps, and if I didn’t have a wireless (RF) pool temp gauge, this would be how I would do it

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