I have various temperature sensors around my house, and I am never quite sure where to place them. Do I place them on the ceiling? Somewhere on the wall about half way up? Hang them off a string in mid air? OK, maybe not on a string, but what is the best?
For sensors in living area, placing them at seated height (say, on a side table) seems to make sense. For areas like our garage, I place them in areas I want to monitor for "safety" that might freeze first and have bad consequences, such as near the pipe to an outside spigot that sits near a door (I didn't design it or plumb it, folks). I would generally avoid floors and ceilings.
Hi - I too was a bit stymied by the whole sensor location question - here is a link to a recent post - theres a few useful tidbits in the 3 minutes of reading!
Keep in mind that temperature sensors are rarely single function - often they are 'multi' sensors capable of motion, humidity, illuminance and even others! Since a temperature sensor is not 'real-time' - that is to say it is sending it's status at some pre-defined period or schedule it can also be affected by the location not just by the height but location relative to heaters and vents.
Last, I would really consider the 'how many' issue - initially I wanted one in each room of the house only to actually see over time the variance was really minor! Placement in the hottest and coldest points of the house and of course the temperature provided by your thermostat (commonly located at shoulder height, central to a home) will give you the Delta values above and below your central reading!
In the end, I used an 'averaging' of all my sensors with a display of tenths of a degree. I also learned not to overdo my thinking - a rule or action your Hubitat can do, can be specific to just one room so in the case of one of my sensor locations being extremely odd (the office floor) I just put a single sensor there that controls a nearby portable heater. I tend to overthink!
I too have several of my sensors on side tables and office desks and night stands, and such. That seems to work reasonably well as far as sensing the temperature. But they get picked up by people, and knocked on the floor, and just generally speaking, I think they should really be out of the way.
I would just like to attach them to something where people can't see it and be done with it. The ceiling would be the most convenient for that. (Note: I actually have several temperature sensors that are just temperature sensors). But then of course, that is going to be the warmest spot in the room, which is less than ideal, obviously. I have also considered places like window sills, but surely that isn't ideal either. So just on the wall? Hmmm... It's a conundrum.
I have a very pragmatic approach for this (even I have also different sensors placed in various places): the thermostat sensor and our body.
Whatever the temperature measured by any sensor, your body is the final best sensor in your automation: if you feel cold, heat a little bit. If you feel hot, cool (or stop heating).
I tricked my wife for "experimental purposes": for several weeks, in the night, I lowered the temperature of 2 degrees and increased the display by 2 (to display a false but still confortable temperature). Almost all the time, she raised spontaneously the thermostat to "24C" instead of "22C" because "it was too cold"...
Body temperature and global feeling are the best sensors ! The rest is just data analysis
One additional thought on this; Consider double-sided tape and use it to stick sensors under tables and on the back of things near a wall. I do this in my office, where a sensor stuck to the back of a small set of drawers controls the temperature of the office itself. Works well, keeps the sensor out of the way, and no one picks it up to ask, "What's this?" (thereby messing with its readings).
Keep in mind ensuring air flow to the sensor. Mine (SensorPush) have a tiny hole on the back to provide airflow into the internals of the sensor. I can only assume that, in my situation, affixing the sensor so close something may limit the amount of air that could flow into the circuitry detecting the temperature and humidity.
Keep in mind that where ever you place them it will be wrong
Joking aside, folks look for super precision temperature sensors (me included). In reality if one could take a flir photo of a room in temperature 3D they would find the room temperature variation is substantial. So keep that in mind when looking a temperature to a 1/10 of a degree.