I want to add a remote temperature sensor that will trigger my thermostat and I was thinking about a motion sensor since they report temperature as well as movement. Is there any disadvantage of using a motion sensor this way?
How does a generic motion sensor compare to a compatible one? I saw my Home Depot has a wink combo pack with motion sensor and 2 window sensors for $50. Otherwise the SmartThings motion sensor is on sale for around $30.
There are many sensors that report on multiple attributes: motion, light level, temperature, humidity… These are actually different sensors in the same case, so you could certainly use the temperature values if you like. The biggest disadvantage is that the less expensive multiple sensor devices also tend to be less sensitive than the more expensive ones. For temperature there might be a +/- of 4°F, which many people would find insufficient for controlling a thermostat. So you just have to read the specs for each model you’re considering.
As far as specific motion sensor recommendations, or, for that matter, temperature reading device recommendations, I’m sure you’ll get many responses. Everybody has a favorite, often for different reasons.
The following thread goes over some of the different possible features for the major device classes, so it might also be of interest.
@yvesracine has done a great deal of work with thermostats and may have more thoughts on different brands of sensors.
Second the Iris Motion. While it does not have sensitivity adjustments it works really well and is tiny compared to everything else. The price point of $30 is very competitive too.
I like the Aerotech Multisensor 5, but unless you want Humidity and Lux (not perfect on it) I would skip it and go with the Iris.
The disadvantage of using a remote sensor for thermostat is the reporting interval. Some report per degree change, some report on an interval of an hour. I have a few of the wink motion and they are slow to report.
Yes, I know a little bit about sensors as I’ve worked intensensly to integrate them with
my Zoned Heating/Cooling solutions and with my ecobee device implementation.
I’d recommend the following 3 sensors:
Iris Motion/Temp Sensors
Wireless Tags (for Temp only) http://wirelesstag.net/
I love the wireless tags for their small form factor and their long range.
For those of you who are thinking about purchasing the ecobee3 thermostats, (and even though, I’ve worked a lot on the ecobee-SmartThings integration in the past 2 years), I would not recommend
the ecobee3’s remote sensors as the motion component is not meant to be used in real-time for HA
So it sounds like the Iris motion sensors are the favorite. They appear to work well and the price is great. They have a 4 pack for $65 (after $10 off coupon). That seems like a really good price point. I also found this discussion and these can be calibrated to be accurate within 1 degree.
The other option that I saw is the Iris window and door sensors. Does anyone have experience with these? Lowes has a 4 pack for $53 (after $10 coupon). To bad they don’t have a pack with 2 of each.
The Iris devices are very popular, you will find much discussion of them in the forums. Just make sure you get the second generation, in the purple boxes. Not the first generation in the clear plastic boxes. The second-generation can work with SmartThings. The first generation cannot.