Emerson Sensi Wi-Fi Smart Thermostat for Smart Home, DIY, Works With Alexa, Energy Star Certified, ST55

First off I had a 4-wire thermostat that was on my system with 3 postion switch... heat off cool.. No emergency heat...it's a air conditioner with an electric heater (not heat pump heater) all in one Goodman unit ..... there was a yellow wire. a green wire ..... white wire and a red wire....and a jumper wire between RC and Rh that's all... I had no C wire and this absolutely 100% works on my system with no C wire the batteries keep the screen lit ....... the wifi everything hooks up fine..... So 5 stars for the thermostat pretty easy to setup.. Need to start a account with sensi Free no big deal.. App works great.. Now for me the downside is it doesn't work well with Alexa it doesn't do the basic commands you can go to heat and you can go up and down on the temperature. Couldn't get it to actually turn the AC on or turn the unit off..... The Sensi app works fine up down temperature everything works great heat ac automatic... just doesn't work all that that smooth with Alexa. Over all .... So if just a good easy wifi thermostat I would highly recommend this....... Updated update update update 1/28/18 wife figured it out... works great 10 stars You have to say exactly Alexa set thermostat setting to cool Alexa set thermostat setting to heat Alexa set thermostat setting to off Alexa set to what ever degree you want

Purchased this model based on the good reviews and the no requirement for a c-wire. Decided to replace my 17-year old RobertShaw thermostat (t-stat) because I wanted remote capability. I was hesitant to touch A/C wiring whereas I had no experience with A/C wiring. The A/C company wanted $90.00 to install it, but I decided to do it myself since it was just a 4-wire system. (no c-wire). It took me just 15 min to remove the old, and then install/wire up the new t-stat. That's how easy it was. Was able connect the t-stat to my 2Ghz wifi network and used the Sensi app on my mobile. Everything worked just fine. No issues at all with wifi setup and using the app. It works exactly as designed. You can make t-stats adjustments either by wifi or LTE on your mobile. No delay in signal. My wifi has never lost signal and has stayed up now for 1 week. The t-stat itself (on wall) has very few settings. Just has temp control, fan/auto/heat/cool and wifi settings. All other settings are done via your mobile. There is also a light switch at the top of the t-stat that when pressed, stays on for 10 seconds, then turns off. BTW: The t-stat light is always off until you press any button. LCD screen is very easy to read with or without the light. One of my requirements for a t-stat was to have a differential as to how much longer a unit will run once it hits its set temp. This model does not have a adjustable value, but does have a "cycle rate" of slow/medium/fast. I set mine to slow to keep it from turning on/off too many times. From the measurements I have taken with a infrared thermometer, the "slow" cycle has a differential of 0.7 degrees. This seems to be inline with what Emerson says (actually, they say within 1 degree). Important note: If your home loses internet access, you will NOT be able to control the t-stat, even when you are at home on your local intranet. Some systems still let you access your devices via the local intranet, but this t-stat require cloud access 24x7. Now, in case your t-stat screen is locked, and you lose internet connection, you have no way to do any changes on the wall unit since the screen is locked and your mobile is the only way to unlock it. In this case, Emerson has a key sequence you can press on the wall unit to unlock the display. (btw: the screen lock is a feature that you enable on the t-stat to prevent people from making changes on the wall unit) Small issues: The light switch at the top of the t-stat is hard to find and press. I never hit it on the first attempt. Always have to feel around at the top and press hard. There is one problem I constantly hit. I goto my Sensi app and change any setting (temp, lock/unlock screen). The Sensi app accepts the setting changes, so you think all is good. However, when I look at the t-stat on the wall, no changes occurred (see attached picture). This has happened numerous times each day since I have had it. Called support and they are not aware of any issues. In each failure, my wifi signal is up - no problems with wifi. After a few days of this happening, I see the problem. It does not appear to be the t-stat, but rather the Sensi app itself. It somehow is hung up, but gives the appearance that it is operating. If I kill the app, and restart it, the sync up to the t-stat is working again. Each time that the app behaves this way, I just kill and restart it. Works every time. So, each time I use the app to make a setting change, i just kill the app and restart when I need it. The accuracy of the t-stat is pretty accurate (within 0.5 degrees of my infrared thermometer) Overall, love the product. I can easily control my t-stats from my mobile or directly from the wall. Makes life very easy now. Update: 12/10/18: Product has worked flawlessly. No issues at all with wifi connectivity. Never had a dropped connection. Both wifi and 4G LTE connections always connect just fine. When making thermostat changes on your cell phone (wifi or 4G LTE), changes take effect within a couple seconds. Also, the problem mentioned above regarding the app freezing when your cell gets out of sleep mode, this has been fixed a while ago in an updated Sensi app. All around, everything works great. Love this product - makes it very convenient to remotely control your AC. Update: 3/1/2020 Everything has worked flawless. Still have original Energizer AA batteries (full bars). Never had any LTE/Wifi connectivity issues.

Will not reconnect to the router even if just a brief power loss. Battery backup does not save pin or passwords, has to be manually reconnected every time. If you aren’t home you can’t do anything, just get an error message until you go home and reboot it. Will be replacing it with some other manufacturer’s device that does what even the most inexpensive internet device does and reconnects automatically