Honeywell Home - T9 Smart Programmable Touch-Screen Wi-Fi Thermostat with Smart Room Sensor - White

Used to work until recently. Device no longer communicates with the "cloud". Nothing changed in my LAN/wireless setup but Resideo claims it is a LAN/wireless issue on my end. Strangely enough Resideo was doing "maintenance" the day all my devices stopped working. Hmm. Tried to resolve with Resideo but it was a complete waste of time. Looking for alternative solutions as we speak. (31July2025)

It's a great tstat when it works. I have had multiple times watching it reset. Sometimes it just turns off and I get up and pull it off to reset it. I'm probably going to get a power monitoring meter with data recording so I can prove to honeywell that the Stat socks and it's not the furnance.

The heating and cooling functions work fine but if you need a thermostat to control ventalation or a humidifer using a U1 or U2 connection, this is not the one for you. While the wiring diagrams and images on this site show it has U1 and U2 wire connectors, when I received my thermostat, it does not. The installation instructions say very clearly it will not work for U wire connections. So... which is it? It is very misleading to show the connections. Had I not needed to use the new thermostat for heat because it was -4 degrees outside and I was going out of town, I would have definitely returned it just because I don't appreciate the inaccuracy, whatever the reason.

I have used T9 thermostats on my two Carrier HVAC units since 2020. Two issues: 1) On HVAC unit #1 there is a large temperature overshoot when heating. For example, assume the set point is 73 F. The temperature shows 73 F when I hear the furnace stop firing. But by the time the fan stops the temperature reaches 77- 78 F. I wish that there was a tuning parameter that I could adjust to make the furnace kick off a bit sooner so as to reduce the overshoot. The performance when cooling is reasonably good. 2) On HVAC unit #2 the T9 reboots almost every cycle at about the time that the set point is reached. The T9 on HVAC #1 rarely reboots. The company that installed my HVAC units says that rebooting is the fault of the thermostat. On the plus side, the display is great - easy to read. And the APP is very good. For me, I've learned to live with the T9's limitations. However I would be reluctant to recommend it.

Very easy to wire up and to get set up to use. Handy to use with the app even when I am not there.