Best/easiest temperature sensor for automation?

I have a ceiling fan in my bedroom which gets poor air circulation compared to the rest of the house.

My goal is to trigger the fan to turn on once the temperature in the room reaches a certain point. At the moment nothing about the room is “smart”. I will be installing a smart switch and was looking at the Lutron Caseta, but I am not tied to it. Any switch will do. I am more concerned about the temperature sensor. Preferably I would like a simple thermometer/clock that has wifi capabilities. I really don’t want to have to get a sensor that requires a hub. If I have to go down that route I might as well get another HUE since I already have a motion sensor. I just don’t know if the temperature feature on the HUE is worth getting into.

Any recommendations?

DIY or off the shelf?

Off the shelf. Everything I seem to find through quick searches either requires a zigbee or zwave hub and the wifi ones are expensive for what they are.


How about a ConBee II ZigBee stick? It’s conpletely local, great integration into HA and lots lf compatible devices. You couls then also move your Hue stuff to the stick and ditch the Hue hub. This will also allow you to get instant response from Hue remotes/sensors etc. because with the ConBee stick changes are pushed to HA instead of HA polling the state at a fixed interval.

Something like that is tempting…would it plug into my HA on the rpi or would it need to be plugged into a computer or usb wall outlet?

And if it it is more instant than the HUE hub then the difference would be possibly be immeasurable without a meter…the light changes are instantaneous as far as I can. One foot through the doorway and the lights are on before I take my next step.

I started out only needing 1 temperature sensor then it was 2, then an outdoor unit found it’s way under the tree, well you get the picture. I am using rtl_433 & a USB RTL-SDR, it handles all my temperature needs, smoke detectors and a remote button unit. The 433 also gives more range than just wifi.

That’s what I’m going through right now LOL. I resisted home automation. I have a Google home mini unopened still in the shrink wrap. I received it as a door prize at an event a year and a half ago. About a month ago I got this idea that it would be nice to have auto dimming lights but, I did not want voice activation. Well…I started going down the rabbit hole and here I am running HA after never running a command prompt in my life before June.

What do you class as expensive, and what part of the world are you in?

$150 is expensive for a thermometer like this. If I could get something like this that doesn’t have the monitoring, possibly without an app and about $100 less that would be awesome. Really what I want is just a small stand alone device that has a LCD clock like display and connects to wifi. Obviously I am open to other options but, that would be ideal.

I am on the east coast of the US.

Then try this for under $30, wifi connection, MQTT support so works well with HA, tiny, battery lasts a year.


oooh. I will look into this.

Do you know if this shelly sensor sends data in 0.1c increments? My sonoff TH series is basic and I receive 0.6c increments only.


I don’t know: I don’t own one. The manual shows a screenshot showing 31.1°C; but the API reference isn’t clear. This particular device is designed for long battery life and few sensor reports; but can be powered via micro-USB and report more often if you want. It was just an example of sub-$150 wifi units.

Personally, I’d build a little sensor unit from an ESP8266 and a DS18B20 (or DHT22 if I cared about humidity) using ESPHome. It’d cost me about $10, report to sub-0.1°C precision and be expandable to include other sensors if I wanted.


A little more diy focused, but if you purchase a cc2531, flash it with the custom firmware for zigbee2mqtt.
Can plug into your pi as well.
From there, the zigbee world opens up and all devices are relatively cheap from there in out ($20ish)
I personally use the xiaomi sensors and work surprisingly well

I’m thinking about Xiaomi because of the price.

I want something as simple as this with wifi instead of bluetooth since the sensor will be 2 floors above the rpi. I also don’t have anything apple except a atv.

Are there not simple pucks with a display that broadcast over wifi?

You say you’ve already got a Hue motion sensor? They also include a temperature sensor. I have one Hue motion sensor plus multiple Xiaomi temperature sensors, and the temperature on the Hue motion sensor seems pretty accurate. I also have multiple Xiaomi door sensors, which also report temperature, but they don’t seem very accurate at all.

The price of the Hue motion sensor is annoying, but it’s a far simpler route if you’ve already got one.

I went for the zigbee path when I started with home automation. Bought some aqara temp&humidity sensor, after that some Konke and used them with zigbee2mqtt.
But when I really started to play around with automations (especially heating system) I found out that the delay of the battery powered zigbee sensors is not helpful into a “smooth” and sensitive heating system.
My main goal was to have +/- 0.3° C tolerance from the setpoint, but because the zigbee sensors sometimes didn’t triggered for 40 minutes, I ended up having +/- 1° C tolerance.

So I switched to Xiaomi BLE Temperature Sensors, which are very sensitive. Of course, the main downside is the limited range of the bluetooth signal, but it can be compared with the zigbee network, which will require some routers to work properly

I looked at the Xiaomi but am now put off by the range. We have electric underfloor heating with insulation in the floors for this which even blocks out some of the 2.4ghz wifi signals. Had to install a cat6 cable through the walls from the main router room upstairs to downstairs with extra routers there.

I imagine I’ll have even bigger problems if I try to go down the bluetooth route

Yeah Bluetooth is a deal breaker for me. I have 1 rpi on the ground floor where my router and tv are (only tv in the house) and I am trying to automate devices on the 3rd floor. Last resort would be an additional hub/zigbee/zwave stick.I have an orbi ax6000 mesh network wit gigabit internet so range and bandwidth are no problem. The easiest thing to do would just be getting another HUE sensor but, for what they are they are expensive especially since products like the Shelly H&T are considerably less and equally as effective. Plus I want a screen. I don’t want to have to open an app or poll HA to get a temp reading. I’m curious. I sometimes just want to know what the temperature is by looking over at the sensor. The eve would be great if I bought into the apple ecosystem which I don’t. DIY is also out of the question. I have never worked with a command prompt in my entire life until 2 weeks ago I decided I wanted to learn HA. And I’m glad I did. But I don’t have the tools necessary much less the knowledge to DIY beyond finding a device that HA auto discovers (it took me 10 days to figure out how to get the apple tv custom config working). First world problems, right? LOL

Bluetooth is easy. Use one of the Xiamo sensors (the hockey puck units) that provide local display of temp and humidity (and battery status). You can then flash an ESP32 with ESPHome and it will talk to the sensors through bluetooth and send that info on to HA to use in automations etc.

I have a number of these sensors around the house now and the WAF is high - she can see the temperature in the location she is in and i can pick up all the info for HA to work with.

Each sensors costs about $17 (AUD) and an ESP32 and USB power socket cost about another $5 - a single ESP32 can handle a heap of these - the range seems to be about 10-15 metres in all directions - depending on what obstacles are in the way.

I have read but have not yet tried - a Raspberry Pi Zero W has great range and can do a similar thing - but not as slick as with ESPHome - so you would send the result back over MQTT for managing in HA - obviously the RPi0W is much more expensive also


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