I wanted a thermostat that I could adjust via an Internet connection. After a lot of research on line, I bought the T9. I installed it myself, which was easy. The instructions were clear and easy to understand. I highly recommend this product.
diy install was fairly easy. tstat works as promoted. app interface was easy to connect and works as described. imo, only drawback on this tstat is that there’s not a way to adjust temp variance. once a temp is chosen, furnace turns on often to keep the temp exactly at the chosen temp, rather than float a bit ( +/- 2 or 3 degrees) prior to calling for service again.
I purchased the device a few years ago, but did not install it right away. After replacing our HVAC unit, we had to pull new wiring for the thermostat anyway, so installed this one. It has performed nicely. I wanted a remote sensor as well. I bought 2 newer ones that were incompatible before learning it needs the older technology.
The good: Remote management. The not so good: schedule only have 4 settings; many of the settings are not available to change such as the cycles per hour.
Excellent thermostat. My wife and have it set so that it senses when we leave the house using the geofencing feature; works great. One serious problem, the instructions are poor at best. Be aware that in order for the geofencing to work properly for more than one person/cell phone, each cell phone owners has to have their own Resideo account. The instructions do not tell you this. I learned this by calling into the support center. They were very helpful.