Emerson Sensi Touch Wi-Fi Smart Thermostat with Touchscreen Color Display, Works with Alexa, Energy Star Certified, C-wire Required, ST75 Black 5.625″ x 3.4″ x 1.17″

A rough start, but works great
Update #3 (25 Feb 2023): Well, it has been over 4 years already and the thermostat has been working flawlessly all this time. We’ve lost power to the house several times over those four years, we’ve had numerous internet outages, and I’ve changed out our cable modem and wifi router a couple of times with the latest setup being a mesh system. The Sensi has weathered all of that, coming back online each time and running without a glitch. I’m not sure what more you could ask of a product. Definitely a 5-star item!Update #2 (2 Dec): Just a quick update to report that the thermostat has been working great now for over three weeks… no glitches, no wifi disconnects, and no reason to believe there will be any issues. The connection to Alexa is also great and very responsive. Very happy with this choice for a new thermostat!Update (10 Nov): I’ve updated my rating to 5 stars now. The Support team contacted me by email and provided a detailed rundown on configuration settings available under advanced settings. It turns out that the Sensi had auto-configured to a different type of furnace than I have, so once I made the appropriate changes I was able to reconnect the Green (fan) wire and the unit works properly. I’m not sure why this information isn’t provided in the setup documentation, but I appreciated the Support team providing a courteous, prompt and detailed response.I also loaded the Alexa skill for Sensi, which set up quickly and it works well. I can now inquire about temperature or change the setting by voice. And of course when away from home, it’s nice to have a single app (the Alexa app) where I can communicate with furnaces, light switches and electrical outlets if I want to.The bottom line after having the unit in place for several days: I like it and am rating it 5 stars. Yes, it was a little painful getting here, but it’s doing what it’s supposed to, it’s very easily programmed with any schedule you like, the wifi continues to function normally, I like being able to check my phone from anywhere and see what the furnace is doing, and I really like the way it looks on the wall, including the color change when it turns on the furnace and the dimming feature that provides a dim display of temperature that isn’t overly bright or annoying at night (of course, you can shut this off). I like it enough to overlook the start-up issues. Providing it continues to work properly in the coming weeks and months, it’s exactly what I was looking for.Original review (8 Nov): Although there are mixed reviews of this thermostat, many of them appeared to be software related, and software can be updated if the company stays on top of issues, so I thought I’d give it a try anyway. It’s definitely a nice, sleek looking unit, and programming/using it is straightforward and very flexible as you can set up virtually unlimited schedules.Hooking it up was pretty easy, as there is normally no real rocket science to thermostats and furnace control. My upstairs furnace is about 18 years old, and control requires minimal wiring. So while the original thermostat had 4 wires connected (Red for 24 VAC power, White for heat call, Yellow for cooling call, and Green for fan control), I had no common (C) connection available at the wall. Fortunately, the cable had six wires in it, so a 10 minute visit to the attic (where the furnace is located) and I had one of the spares connected to the furnace C terminal.Fired the furnace back up and the Sensi came to life… and this is where some minor troubles began. Setup to wifi requires doing a little configuring using the Sensi app. I installed the app on my Samsung (Android) phone, which completed quickly. Unfortunately, when the Sensi wifi transmitter was supposed to be transmitting, the app was unable to find it. Checking for all wifi signals on my phone, there was no signal from anything other than my router and a weak router signal from a neighbor. I tried switching the Sensi wifi on/off a few times with no results. Then I found a system reset option, so I tried that and the display simply hung… no reset, and no ability to do anything.I figured this might be a good time to call the Support number, which I did. They responded within a couple of minutes (which is great), and the solution was a power cycle, accomplished by simply removing the Sensi from its base on the wall and putting it back after 5-10 seconds. This time, the wifi came up as it should, so I hung up with Support and I was able to configure the thermostat. I noticed the room temperature indicated 77 deg, which was about 9 degrees higher than it actually was, based upon two other digital thermometers that both read exactly the same (68 deg). Then, about 5 minutes later, after tinkering with system options in the app and finding a temperature offset adjustment that provides only up to plus or minus 5 deg (well short of 9 deg), suddenly the Sensi went offline and the initial wifi setup screen returned on the unit. At this point, I could have just gone thru the wifi setup again, but with the significant temp inaccuracy, I thought I’d call the Support guys again and discuss what was happening. Again, they picked up within just a few minutes.The solution here was trying a system factory reset, and this time the splash screen came up after half a second rather than hang like the first time that I tried it earlier. Apparently, the factory reset also initiates a calibration, which for some reason can take a full day to complete… but it doesn’t impact being able to use the thermostat. So, following the reset, I hung up and completed the setup again. Things were back to normal, and within a couple of hours the indicated room temperature slowly moved downward to within 2 deg of those other thermometers. By the next morning, it was still 2 deg off, so I selected the -2 deg offset and all was well. So clearly, the calibration function works fairly well.After operating for a while, I found that the cycle rate was much too fast as the furnace would start back up shortly after shutting down, so I adjusted that to the “slow” setting. After letting it run overnight, I discovered in the morning that I no longer had heat! After a little checking, it turns out the flame sensor in the furnace was no longer detecting the flame, which after a few seconds shuts the flame off. After three such cycles, it locks the furnace. This wasn’t initially apparent because the Sensi wants to start the blower fan when it calls for heat, so it sounds like the furnace is running… except it’s blowing cool air. Furnace electronics are designed to allow the furnace to start up and develop a little heat prior to starting the fan… this is unnecessarily overridden by the Sensi. My belief is that this air flow starting before the furnace ignited must have had some effect on an old and somewhat dirty flame sensor. Cleaning the sensor fixed the start-up problem, but it still makes no sense to blow cold air out the ducts on start-up. So for now, I simply disconnected the Green fan wire attachment in the Sensi base, and everything is working normal. I sent a summary of this concern to Sensi in writing, questioning whether there’s an app setting I missed, or this unit (when set for gas heat) is defective, or perhaps this feature is a design flaw. I’m awaiting a response.One other note: there’s apparently at least one little bug in the app… occasionally when you’re connected to a specific thermostat and you use the back arrow button to go to the previous screen that lists all thermostats (of course I only have the one), the app will display it’s “working” indicator (an animated blue target looking thing) continuously and not take you back to that screen. Killing the app and starting it up again returns things to normal. It’s minor, but it has done it a few times and it would be more pleasant if it always worked.So after a rough start, things seem to be working, albeit with my little Green wire modification. I’ll update this review as I learn more or if there’s a failure anytime soon.

Easy to install and program. App works great!
This was fairly easy to install. Only difficulty was connecting the previously unused spare wire in the cable at the air handler end. And that is only because my air handler is in a tiny attic space that’s difficult to access.Once installed, it was easy to program and seems to be working great. I have the app on my phone.The system sends me a text when it detects an out of normal range situation, usually when we have windows open and it sees higher humidity.

So far this thermostat is working very well as a replacement for an old-style analog Honeywell. The touch screen is easy to use, setup and home network integration are a breeze, and it easily connects to Apple Home. The Apple Home app functionality is very basic, but I like having the ability to run automations or use voice commands with Siri. The Sensi app on the other hand has a lot of features, and is well-designed with a pretty intuitive user interface. It’s only been a couple of months but I’m very happy with it thus far.UPDATE: It’s now been over a year. I have had no issues at all. The only time it drops connection from wifi is when the power or internet go out. The app is just amazing. You can do a lot but it’s not clunky or confusing. They just keep making it better and easier to use. One of the best smart home device apps I have ever used. I hardly ever use the touch panel.

I like the ability to use my phone to access remotely. Very simple to install. The app install tutorial provided step by step instructions which were very easy to understand. Nice screen making the current temp easy to read.