I’d like to monitor temperatures at about 5 locations around the house.
Most of the hardware I see seems to be multiple sensors. That’s great, but I’d rather not pay for motion, humidity, contact, etc. All I need is a thermometer.
Any suggestions?
How are you wanting to communicate with OH? Are you OK with DIY approach? Will the device be battery powered or other?
If DIY works then I would recommend looking at using an ESP-8266 chip with a temp sensor DS1820.
Thanks, good questions. I’m pretty much DIY’d out right now, trying to learn the Raspberry Pi, Linux, OpenHAB and all about home automation in general. A plug-and-play solution would be better.
AC power would be available where I need the sensors, but if a battery operated solution worked out better, that would be fine.
I keep finding stuff about the Xiaomi Mijia, both good and bad. Even these seem hard to source; Amazon wants more than anyone else, and there don’t seem to be many vendors selling multi-unit packages, meaning I pay for “free” shipping five times over.
So here is the problem. The cost of the sensors when purchased in bulk is in the sub ten cents per unit range. Consequently the difference in the amount it takes to build something with just a thermometer compared to a multi sensor with humidity and PIR is pretty close to zero.
You won’t find a stand alone sensor completed sensor that has just temperature because the vendor’s can’t charge less for it. It costs just as much to design the board. It costs just as much to set up the production line. The only difference is maybe 20 cents worth of materials.
Thus, even if you could find a stand alone thermometer sensor that could talk to OH, it wouldn’t actually save you any money. So if you are not up for going DIY, just buy the multi-sensor and ignore the sensors you don’t care about.
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Do you know www.mysensors.org? If you are willing to diy you are able to make a temp sensor for about 4 euro on battery which lasts for about 1.5- 2 years
The Xiaomi Sensors works very well. You can buy the xiaomi gateway or you buy a zigbee gateway. For example the raspbee from dresden electronics. The implementation in openhab is very easy and the sensors are small and cheap. The batterie life is 1.5 years.
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Thanks for the vote of confidence in Xiaomi. I was leery of going for the lowest cost, but if they work, that’s all I need to know.
I’ve got a HUSBZB-1 hub on my Raspberry Pi 3. Will this work with the Xiaomi sensors?
I use the Xiaomi Gateway. But I also tested it with the Raspbee. I’m not sure if it works with your gateway but you should think positive. 
Look at this Link Howto use zigbee2mqtt with openHAB, removing proprietary bridges / gateways
I use Netatmo, a bunch of multi sensors speaking z-wave - and then three Telldus Thermometer/Hydrometer (313160). The latter are cheap, unsecured, speak 433MHz and can be bought in packs of three. They are generally speaking +/- 2 degrees celsius in precision, but that seems to be quite normal for most sensors. ^^
The gateway you buy may or may not be able to work easily with openhab. Currently some versions can’t have the developer port unlocked.
That’s what happened with me, so I then tried using a Dresden Conbee controller which I was unhappy with, so then ‘built’ (just reflashing a usb, takes 30 secs and no big hassle) the zigbee2mqtt controller and use that system which i’m happy with.
The Xiaomi Aqara sensors are great.
@DSTM
Nice to hear that it works well with your system. I have the Gateway for 2 years and i don’t have problems with the sensors and other things. The advantage of the Xiaomi Gateway is that you can implement the Xiaomi lamps and vacuum cleaner with little effort. You can not do this with the Zigbee Gateway. Two years ago, there was only the solution with the gateway. But thanks for your information. What kind of gateway do you use?
Xiaomi make a decent range. Bridge is not too pricey and sensors are cheap enough. Aliexpress or banggood.com are your friends.
a reflashed CC2531.
All the details here:-
https://koenkk.github.io/zigbee2mqtt/getting_started/what_do_i_need.html