Inexpensive NIST thermal probe with cloud storage but no SmartThing integration?

Hi everyone,

I’ve been recording temperatures from 14 devices, for some years now.

All my SmartThings data goes to a Google Sheets log every 10 minutes.

While my temperature sensors seem pretty good, they differ from each other by a degree or two Fahrenheit when side by side. (It’s 9 Aeon Labs gen5 Multisensors 6s, 4 Samsung SmartThings Multipurpose Sensors, and 1 Samsung SmartThings Motion Sensor, 2016 version.) They’re not NASA quality, but you don’t expect that from $50 devices.

Still, I would like to calibrate them with something good. I am calling this “good” thing an “NIST thermal probe” for purposes of discussion, although I suppose it doesn’t have to be NIST-calibrated… just some decent sort of calibration, and precision.

Because my Google Sheets log is “offline”, the probe can also store to cloud. What I will do is put the thermal probe next to each smarthome temperature device (in its normal location) and let them both collect data for about a week. Then compare their data together (as a temperature difference at each point in time), and use that to “calibrate” the smarthome sensors. Like, the smarthome device needs an average offset of +1.3 degrees to match the NIST probe, or whatever.

I’ll move the probe from one device the the next, taking a few days or a week at each one. After it’s all done, I’ll only break it out and do all this again maybe once every two years. (Unless some of them seem problematic. In which case, I’ll look at them more closely. A couple are in the attic where it gets up to 130 F … I live near Atlanta GA.)

Sorry for all the typing. To make a long story short, here is what I’m looking for, ideally. A calibrated temperature probe that:

  • Sends data by wifi, probably to the cloud. But really, anything that stores data and is accessible via wifi is good enough.
  • Stored data can be copied to a spreadsheet (or is in one already). That’s how I’ll compare data from the sensor pairings, side by side.
  • I don’t mind paying $100 and change, but $200 seems too high for something I’ll only use every now and then. Unfortunately, many of the calibrated probes I could find at first glance are over $300.
  • I would really want it to be able to capture something like -20 F to +140 F. That’s about the range in my house and outdoors (including the attic).
  • At a precision of 0.1 degree. And an accuracy of something less than a degree.
  • The ability to connect at least two calibrated probes to the probe device would be nice. So I can check that the probes themselves like to agree, and have a little flexibility when measuring around each smarthome temperature sensor.
  • SmartThings integration (or device type handler) would be a real plus, but is not at all critical. (I will be doing the comparisons in an off-line mode, but it is convenient if I can get it to send its data right to my Google log already.)

When I do Google or Amazon searches, I get SO many results. Many are for specific purposes, like ultra-low temp freezers, etc. Also, I couldn’t find a suitable subreddit. This topic is not completely on-target for a SmartThings Devices subforum, but it’s the best I can think of.

I just want something that can meet all the requirements above. I’m awash in all the search results, especially when I try to pair a probe base with the probes itself. A number of the webpages describing devices are not very friendly to complete newbies, and assume you know all about the kinds of probes. (They just say “works with probe model [number]”, and then sometimes specs on such probes are hard to find, especially if it makes a difference which devices it’s used with.)

Okay, apologies again for all the typing … can anybody help? Or at least steer me to a good forum where more-knowledgeable folks are?

Thanks if you can help!

P.S. If anybody wants, I could buy a temperature calibration setup and consider “round robining” it to others that might want to use it a while, then return it. Or pass it on to someone else. After all, it’s a lot of expense just to make sure one’s device temperatures are on-target every once in a blue moon.

I know you said probe, but would the Cao Gadgets Wireless Tag Sensors work for you?

The pro model should meet your accuracy, these are nicely engineered devices, and the price is good.

You would need the $29 base station and then the pro sensor is around $36.

They have an IFTTT channel

Or there is also a community built integration, although it’s old and I don’t know if it’s being maintained.

Huh… the Wireless Sensor Tag Pro is a really interesting device, JD. System of devices, really. Has more connectivity and functionality than even I asked for, and a GREAT price. But it doesn’t emphasize its calibration.

I dug back to the datasheet for the TE Connectivity HTU21D sensor it uses. All it says is “Every sensor is individually calibrated and tested”, has a typical +/- 0.3 C accuracy, and shows a graph of accuracy versus ambient temperature. (Important to know.) It doesn’t say how it was calibrated, but I guess “0.3 C” (= 0.54 F) is the bottom line, anyway.

So it’s not as accurate as something NIST certified, but it’s a real step up from run-of-the-mill smarthome devices, which don’t even bother with saying “calibrated” or give any accuracy estimate at all. (Not mine, anyway.) Given the variation I’ve seen, I’d say my smarthome devices’ accuracy is more like +/- 1 C.

The HTU21D works from -40 to +140 C, much more range than I need (-20 to +140 F) … theoretically I could put it in a pouch in icy and in boiling water to do my own crude calibrating. :smiling_imp:

I’ll ask TE for any more info on HTU21D calibration, and will try to post it here if I get a useful reply.

Thanks for that tip, JD! Maybe I’ll go for it. It’s hard to beat the price.

But still, I sure wish if I was going to sink all that time into calibrating my 14 devices, I knew I had something really solid/absolute to compare them all to.

Any other ideas for calibrated thermal sensors or probes, anyone?

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It would also be great if anyone knows of a particularly good forum to ask this question. It’s not a standard HVAC or device tech question, so I’m having trouble finding a group that is real familiar with thermal probes or temperature sensors these days.