Hi looking for either z-wave or wifi based temperature sensors that are cheap and relatively small that I can place in a few rooms around the house? Any advice?
you could buy some Wemos D1 Mini boards and some DHT11 chips and flash the firmware with Tasmota, esphomelib, or similar.
I prefer to write my own.
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Yea I’ve actually done that before. I find the biggest headache those is powering them, how have you done that?
Usually with just some wall chargers and small 3-6" micro USB cables.
I am actually in the process of designing my own housing for them to 3d print and use with any USB wall charger.
I was thinking about buying some of these and add the DHT11:
Not sure how long the battery will last, though.
I ended up buying the Xiaomi Aqara Temperature sensors - mostly because I needed something smaller for the fridge/freezer - and got the Zigbee2MQTT dongle to work
Not for nothing, but the SHT31 is more accurate for both temperature and humidity compared to the DHT11 and is I2C too. Alternatively, the DHT22 is also a better accuracy option compared to the DHT11.
DHT11:
- Good for 20-80% humidity readings with 5% accuracy
- Good for 0-50°C temperature readings ±2°C accuracy
DHT22:
- Good for 0-100% humidity readings with 2-5% accuracy
- Good for -40 to 80°C temperature readings ±0.5°C accuracy
SHT31:
- Good for 0-100% humidity readings with 2% accuracy
- Good for -40 to 125°C temperature readings ±0.2°C accuracy
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Have you seen the Shelly H&T. They are still on pre order but they may fit your bill.
I am actually sitting here writing some firmware up for testing with a BME280 to compare with my DHT and BMP modules I have
I find the BMP280 sitting right next to one of my SHT31s is never more than a degree different, and typically within 0.2 degrees of each other. I have one BMP280 and 5 SHT31s across the house currently, all connected to their own D1 mini running ESPEasy; dealing with sensors is a lot easier on ESPEasy vs tasmota it seems.
a bit outside the box but I love the Xiaomi Bluetooth temperature sensor with display. You can get the reading via BT and HA on your RPi or using OpenMQTTGateway
I use the ecobee thermostat which has remote temperature/motion sensors. The sensors are relatively cheap. Right now, they are 39 USD for a 2 pack.
ouch.
I think I paid a total of $4 per sensor for my home made ones
flamingm0e - how do you keep the cost that low? Even with cheap boards like the ESP I find the cost to powering the device (usb adapters, etc) ends up making it over $10 min.
I just specced out a basic good accuracy sensor/accessories and yeah, around $10 is about the best I can do. If you shop around you might be able to shave off $1-$2 especially if you buy in “bulk”.
However I’m sure many people have a bin of micro-usb cables and USB wall chargers, so if those are free you can get closer to $7.
SHT30 Shield: $2.52
WeMos D1 ESP-12: $4.93
USB Charger: $1.58
USB Micro Cable: 1.88
Total cost: $10.91
I bought a bunch of Wemos D1 Mini boards from China a long time ago. The more you buy, the cheaper they are. I think they worked out to about $2.65 each. Same with the BMP180,BME/p/280,DHT11,DHT22. I bought a bunch of them (I don’t need shields or hats). I think they were about $0.65 each, and I have USB wall chargers and micro cables laying around.
Even if I had to buy the cables and chargers (buy in bulk and save), I would expect them to run about $1 each
Xiaomi sensor which are like $10 from gear best but look nice and work well, and last 6+ months on a single battery so installation is a breeze!
Second that. I have the old ones (round) and the new ones (square) which also measure atmospheric
pressure. I even have a couple of then inside my fridge :-). The downside of the xiaomi sensors is the need for a gateway and you can’t control when it will update HA. You can’t set a “refresh” rate. But they are cheap, battery can last longer than 6 months and you can just stick it (almost) wherever you want.
Do even the ones in the fridge last that long?
Do you have one in the freezer as well?
I’ve used mine for about 10 days now and the status message says that the batteries are supposedly down to 15% already.
how does the signal work being inside of a big metal box?
@finity, signal is good (that suprised me too). I have a gateway about a room of distance.
@chairstacker I didn’t put one on the freezer, but the one on the coldest shelf (about 4C ) is there for 3 months now.
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