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

(10 customer reviews)

Price: $129.99
Sale Price: $101.11

You Save: $28.88

SAVE ABOUT 23% ON HVAC ENERGY*: The ENERGY STAR certified Sensi thermostat helps you save on your HVAC energy costs, with features like geofencing, 7-day flexible scheduling, remote access and in-app system usage.
MOST INSTALL IN 30 MINUTES OR LESS**: Use the built-in level and step-by-step app instructions for a quick installation. Skip any extra work painting or patching the wall thanks to the standard thermostat size.
EXTENSIVE COMPATIBILITY***: Works with the HVAC equipment found in most homes – a c-wire is required for heat-only, cool-only and heat pump systems. Check system and router compatibility at
SMART HOME COMPATIBLE: Works with Amazon Alexa, Google Assistant, Apple HomeKit (c-wire required), and Samsung SmartThings smart home platforms.
USAGE REPORTS: Monitor current day and historical heating, cooling and fan runtimes right in the app.
GET REBATES: Find utility rebates in your area through the rebate finder at

SKU: B01NB1OB0I Categories: , Tag:
Brand Sensi



Emerson Sensi Wi-Fi Smart Thermostat for Smart Home

smart thermostat, sensi, smart home

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smart home, energy saving thermostat

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smart thermostat, sensi, smart home

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smart thermostat, sensi, smart home

Works With Alexa

From across the room or across the country, your Sensi Wi-Fi thermostat makes it easy to remotely control and schedule your home comfort – Anytime. Anywhere. Designed to work with the wires you already have, Sensi thermostat does not require a common wire (c-wire) for most installations, so it is compatible with the HVAC equipment in many homes in U.S. Canada. A c-wire is required for heat-only, cool-only and heat pump (without aux) systems, and for use with Apple HomeKit. Check to make sure it will work for you at .

ENERGY STAR certified

The intuitive app walks you through each step of installation with custom configured instructions, removing all the frustration and guesswork from the installation process, so you can be up and running in no time, no experience required. Put your comfort on your terms using location-based temperature control with geofencing or creating custom heating and cooling schedules with the flexible 7-day scheduling option with the ENERGY STAR certified Sensi thermostat. Both energy saving features you save about 23% on your HVAC energy usage so you can save money without compromising your comfort. Plus, Sensi integrates directly with Amazon Alexa, Apple HomeKit, Google Assistant and Wink home automation platforms.

Apple HomeKit

Connect to Amazon Alexa to control your home temperature with simple voice commands, or just ask Siri to set, raise or lower your home temperature when using Sensi with Apple HomeKit. Whats more, Sensi Wi-Fi Thermostat has been named the Best Value smart thermostat of 2018 by USA Todays Energy savings calculated by comparing operation time for a nationwide sample of Sensi users with temperature adjustments averaging 4 degreeF vs. users with no adjustments.

Savings vary based on equipment type/condition, insulation, climate temperature adjustment size/frequency. Based on survey results of 2120 respondents that purchased and installed a Sensi thermostat in 2018, approximately 70% reported installing in 30 minutes or less. Adding a common wire may impact installation time. Does not work with electric baseboard heat and some other systems. System requirements for mobile app: iOS – 10.0 or above Android – 4.2 or above (5.0 or greater to use the Geofencing feature).

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

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    So I purchased one of these thermostats from our HVAC contractor when we replaced our AC unit two years ago here in the Naples Florida area. When we arrived in early January, I was unable to connect reliably to the thermostat and I thought that the unit was defective after reading so many Amazon reviews. At that point I decided to order a second unit, thinking that I could return it if it had the same issues. Low and behold it did, so I now wanted to understand what was going on. After a lot of trial and error, even ordering and returning a WiFi range extender, I decided to check my router. As it turned out, I needed to eliminate using 5GHz and went to 2.4 GHz exclusively.Miraculously the issue was resolved and it’s working flawlessly. So before trashing this thermostat make sure that you’re only connecting with 2.4 GHz.

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    I wasn’t sure how this thermostat would work for me but I must say I am very pleased. I live in Florida and usually have the AC off when I’m not home. but by using the app for this thermostat I can turn it on remotely before I arrive which is an awesome feature . some people complained that it goes offline and it does from time and you cant use the app but mine only lasts a few minutes . the Install is easy I used the app and watched a lady on you tube do an install and it was simple . Another feature that’s great is you can schedule when you want it on or off so even if it the app goes offline it will still run how you like . I’ll have mine set to turn on a little while before I get home from work and etc…overall I’m very happy with this thermostat and wish I would’ve bought it sooner ..oh I almost forgot I also have it hooked up to my Amazon echo’s and use my voice to control it as well . many great features 🙂 if your looking for a modern upgrade to your old thermostat this one will do 🙂

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    Sylvester. F.

    So happy with this smart thermostat. I just bought a house in NC and I have never done any electrical work but this was easy to install thanks to the very clear step by step instructions provided by the app. I will say it took us a bit more than 15 minutes, but it’s so worth it. Because we both work during the day, setting up a smart schedule makes so much sense to us. We had this for 3 months and it literally already paid for itself. The app is extremely easy to use. I made a lot of research work and I don’t believe anything fancier (like Nest) would really save me more money than this. I can’t wait to replace my other thermostat downstairs which has zero features (just a number for temperature reading).I will point out to few helpful things:- Installation was easy enough but fitting the cables in the slots requires patience. Don’t get frustrated and don’t wait until your house gets really hot to do this. You will be sweating over the box trying to fit these tiny wires in.- My thermostat is upstair and my router (it’s a modern router I bought of amazon, not the junk the internet company rents you) is downstairs pretty far away. Connectivity works great and the thermostat is always connected. But note I had a C-wire so the batteries are just back-up power for me and I assume this helps.- Finally, I had trouble connecting the thermostat from the app, when i realized that you have to be connected to the 2.4GHz wifi network in order for it to work. My router is a modern “dual band” router so it uses both 2.4 GHz and 5 GHz Wi-Fi (we have two different wifi networks). I usually only use the 5GHz network because it is faster, but I just had to connect my phone to the 2.4 GHz network (called “guest” in my house) in order to pair the app with the thermostat. Scary 10 minutes where I thought that after all my efforts the thermostat was not compatible or too far away from the router.

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    So far so good. Does everything I need. Installed very easily. Holes lined up, hooked up the wires and no c wire needed. Can’t speak to battery life yet, but even if they have to be replaced monthly I will still be happy. It was easy to hook to my network and the temperature adjustments allowed me to get it set to match our old thermostat perfectly. No adjustment period of thinking 70 feels colder or warmer than it used to. It also has adjustable temperature swing for cool and heat, 3 choices for each. You can also set a goal for humidity in the Summer and it will force your AC to stay on a little longer even if the temp is satisfied to clear out extra humidity. Also a great feature.My favorite feature is the apps ability to turn the fan in auto, but select a percent of every hour the fan will be forced to run. This is great for me since my fresh air ERV is hooked up to cycle with my furnace fan. You can select from 10% to 90% of an hour to control or limit how often the fan cycles thus balancing energy use with the amount of fresh air. This feature is great!Hope it lasts a long time, and I will be glad I finally found one that had wifi without a c wire or external adapter.

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    Admin Assistant

    If you are unsure about what you are doing, or if you are not sure if this thermostat will work in your situation, the app or online tools this company provides answer all your questions and give you the reassurance you need. I was very impressed with the clear, simple, detailed, step-by-step instructions, which included optional video links for each step. I also needed to talk with a person from Sensi 3 different times as I installed 10 thermostats at a school. We chose them because of the simplicity of the design and the enormous quantity of professional guidance on the install. It is so impressive that a company in this business market still provides a phone call to a human who knows what they are talking about and is very helpful. If you are not sure which thermostat to buy, especially if you are looking for something in a business setting, I would recommend Sensi. Ease of use means no one will mess up the programming. And the app means you have a very easy way to catch those units that someone in the building kicked on and didn’t bother to turn off when they left! This is the one you want!

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    Bruce Glazier

    My HVAC Details: Natural Gas Furnace/Forced Hot Air + Centeral A/C with NO C-WireI have a rental so I wasn’t about to run a new wire from my furnace to the thermostat. I really wanted to replace the $20 Honeywell thermostat which I had proven was very inaccurate at reading the temperature. I decided to get a WiFi enabled thermostat for a couple reasons.1) After getting a Google Home, I’ve been making a movement toward home automation and voice activated controls.2) My gas company offered a $100 rebate toward a WiFi enabled thermostat so I paid almost nothing for it.Super easy installation.1) Throw breakers for Furnace/AC2) Unscrew wire terminals and pull wires from old thermostat plate3) Remove plate (pay attention to which wire colors go to which designations) and mount new plate4) Re-insert wires into same color designations as old thermostat.5) Plug new Thermostat onto new plate.6) Download Sensi app.7) Turn breakers back on8) Open app and follow the short instructions.Done! The thermostat looks slick (crisp display, Amazon pics don’t do it justice) and the app looks nice too. I haven’t interfaced it to my Google Home using the Wink app yet.So far, I’m very satisfied.

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    Daniel J. Cascioppo

    I did a lot of research on a smart thermostat before purchasing. First and foremost was the ability to monitor and set temperature remotely, and to properly control my heat pump. An added bonus is this thermostat is compatible with Ecovent systems for my future upgrade to zone control. After studying most of the other units available, I came to the conclusion that while Sensi does not boast as many features, the features it has are extremely useful to me. That was the kicker. The fact that this unit costs hundreds less than the more feature laden units out there is also a key factor.I am not fooled by features that won’t be used, or used so seldom as to be superfluous. After all, what do you expect a thermostat to do? Regulate temperature – Check; Ability to schedule heating/cooling – Check, Be able to control from a smart phone – Check. Sensi does it all. As for learning behavior and the other features rife on other units. Those features require expensive sensors, tuning and frustrating and repeated calibration. For what? So it knows how warm to keep the house? Can’t you figure it out? It is my opinion you are better off saving the money, setting a comfortable schedule and forgetting it. The other thermostats to me seem excessively expensive and do no more than this one.Installation is very well done. I had one mystery wire on my old setup. I couldn’t figure out where it went. That was solved with a quick call to the tech support. Other than that, if you can install a light switch or light electrical, you can install this.The web application and syncing the thermostat to the app was easy. Again, if you can’t figure that out, why are you getting a smart thermostat in the first place? Very basic, very intuitive. Not a lot of functions, but they all work.This is a well-designed, well-engineered product. You may want more features, but you don’t need them, in fact most people never use those features anyway. Best bang for the buck on the market.

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    This is how it all begins. The end of man. Alexa took over my house. It’s started on Black Friday 2019. Amazon offered a deal that couldn’t be beat. Once I had SkyNet I mean Alexa hooked up and running it began. I got lazy, really lazy and I loved it. I was hooked. I ordered six more echos. I ordered smart light bulbs and Smart light switches, smart thermostat and smart plugs and Ring cams. It won’t end. Now Alexa is everywhere. Listening. Judging me. Watching. Probably waiting for the right time to strike a blow in America’s heartland. It’s a slow process. But Alexa is patient. I’m so lazy now I don’t get up to turn the light off or change my thermostat. I can even see who’s at the door from my couch. I’m gaining weight slowly. And in a few decades I’ll die, probably of heart disease. The calories I burned moving around and now being stored. My LDL is out of whack. All because I bought an Alexa enabled device On Black Friday 2019. I can hear my arteries clogging as we speak. In the end I was weak. I let the machines win.

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    Great thermostat! It is wonderful being able to simply ask Alexa what the thermostat (inside house) temperature is! Fantastic on days like these with night temps in the 30’s and daytime in the 70’s. Just tell Alexa to set thermostat to heat or cool! Change change temperature settings by voice as well. The Sensi app is great for when you are in bed and you don’t want to get up nor do you want to wake up your partner. Just open the app and make your adjustments. Also using the app when away is great! If you are on vacation and your home area is forcast for a heavy freeze, just turn the heat on from anywhere!Installation was pretty straight forward. Seems that most applications WILL need the “C” wire. I bought the C wire kit but didn’t need it! I was injured and unable to get into the attic. A friend with HVAC experience did it for me. Took about 10 minutes and didn’t need the C wire kit.Setup wasn’t too bad. Had lots of problems at first and called customer service. The Sensi service was down at the time which explained the difficulty. Once the server was back up, it took seconds to have the app recognize the thermostat and mere seconds to have Alexa ready. Just remember to enable the Sensi skill beforehand!I have had the unit installed for several weeks. No issues. I don’t use the program schedules as I really don’t see a need when you can use the app or Alexa at any time but a nice feature for those who use it.I haven’t used the auto mode but I plan to. It appears that you can select heat, cool and auto. I’m curious to see if the unit will automatically switch from heat to cool on its own depending on the household temp. If so, that would make this unit even better than a five star!

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    None Ya

    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 sensiFree 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 1/28/18wife figured it out… works great 10 starsYou have to say exactlyAlexa set thermostat setting to coolAlexa set thermostat setting to heatAlexa set thermostat setting to offAlexa set to what ever degree you want

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