A smart home starts with a Sensi smart thermostat

Sensi offers highly-rated residential smart thermostats, multiple thermostat control for light commercial buildings and predictive HVAC maintenance solutions. 

Emerson ST55

Emerson Sensi Wi-Fi Smart Thermostat for Smart Home, DIY, Works With Alexa, Energy Star Certified, ST55From 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.

Emerson ST75W

The Sensi Touch Wi-Fi smart thermostat puts comfort control at your fingertips whether you are at home or on-the-go. Just a tap of the easy-to-use touchscreen display or free mobile app lets you remotely access, change or program your home temperatures anytime.
ST75W, Tap into home comfort with Sensi™ Touch Wi-Fi Thermostat, and remotely access, change or program your home temperature – Anytime, Anywhere. With thoughtful design features like in-app installation instructions, HD touchscreen color display and smart home integration options, complete comfort control is right at your fingertips.

Emerson ST75

EDITORS CHOICE BEST OVERALL SMART THERMOSTAT by USA Today’s reviewed.com SAVE ABOUT 23% ON HVAC ENERGY*: By adjusting the temperature using flexible scheduling, remote access, and geofencing, Sensi customers saved about 23% on HVAC energy usage MOST INSTALL IN 30 MINUTES OR LESS**: Use the built-in level, illuminated easy-click terminals 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. COMPATIBILITY REQUIRES C-WIRE: Extensive compatibility*** with HVAC equipment found in most homes.

Emerson 1F87U-42WF

The highly-rated Sensi thermostat is loaded with features designed to make it easier and more convenient than ever to achieve the perfect level of home comfort. From a simple installation process to an intuitive mobile app that allows you to adjust the settings on your thermostat for complete control - Anytime. Anywhere. Compatible with Apple HomeKit, Amazon Echo, and Wink Installs and operates like a standard thermostat when not connected to Wi-Fi App changes color to show if the system is heating or cooling Energy Star certified, Geofencing option and smart alerts Built-in dual fuel heat pump option

Emerson ST75-cr

This pre-owned or refurbished product has been professionally inspected and tested to work and look like new. How a product becomes part of Amazon Renewed, your destination for pre-owned, refurbished products: A customer buys a new product and returns it or trades it in for a newer or different model. That product is inspected and tested to work and look like new by Amazon-qualified suppliers. Then, the product is sold as an Amazon Renewed product on Amazon. If not satisfied with the purchase, renewed products are eligible for replacement or refund under the Amazon Renewed Guarantee.

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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)
Retired Engineer
Retired Engineer@username
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This review is a little complicated, but I urge you to read it before buying this product. Just a couple of notes before we get started: 1) This review looks at the cooling cycle of the device; I live in a very warm climate and have not tested the heating cycle. 2) This review covers TWO different Emerson Sensi units of the same make and model; when I first noticed this behavior I assumed it was a product defect and filed a warranty claim with the manufacturer, who sent me a replacement. The same behavior was noted in both units. Without getting into the woes of owning this thermostat (and there were many), I'll just present the finding: In order to control a/c runtimes, the Emerson Sensi's firmware artificially manipulates the device's temperature sensor. I have enclosed three different pictures. Each picture is of the Emerson Sensi (bottom right) and two different thermometers. The thermometer on the left has a clock, so you can see the 'time code' of each picture. The pictures were taken when the outdoor temperature was just about the same as the indoor temperature - around 76 degrees. 1) Picture #1 was taken at 9:18 am just when the a/c finished running and the unit turned off. Note the Sensi believes the room temperature is 73 degrees but the two thermometers show a temperature somewhere between 75 and 76 degrees. 2) Picture #2 was taken just 15 minutes later (9:33 am) shortly before the a/c started running again. Note the Sensi now believes the room temperature is 75 degrees (warmed 2 degrees in 15 minutes?) but the two thermometers show no temperature change whatsoever. Can you say impossible? 3) Picture #3 was taken some 40+ minutes after #2 (10:15 am) right after the a/c finished running its next cycle. Note the Sensi believes the room temperature is back to 73 degrees but the two thermometers show almost no change in temperature from previous pictures (the left thermometer is actually up 0.4 degrees). The three pictures capture a full a/c cycle - off to on and back to off. Somehow, some 'magical force' changed the Sensi's room temperature from 73 to 76, turned the unit on, ran for a few minutes and the temperature magically went back down to 73 and turned the unit off. All when two independent thermometers registered almost NO CHANGE in temperature during the full cycle. There can only be one inescapable conclusion: the Sensi's firmware is manipulating the device's temperature sensor in order to control when the a/c turns on and/or off - completely independent of the room's 'true' temperature. What this means is the thermostat will sometimes run your a/c too much - and at other times, not enough. I will post some 'heat of the day' pictures as time permits, but when it's very warm outside, the thermostat will turn off the a/c far before reaching the desired set temperature. You might think that's good - but it makes for a very warm house. Again, I have verified this same behavior with two independent thermometers. Oh - and one other thing: if you read the manufacturer's response to some of the comments for this product, you'll notice they post this canned message about the Sensi's 'tight' temperature control range of +/- 1 degree. See my pictures: if the variance from the set point is just 1 degrees (specification says it should be 1.2 degrees F for medium cooling cycle) - how is the Sensi's 'room temperature' 73 degrees when the set temperature is 76 degrees? I realize that Amazon has many different products to manage, but deceptive, misleading, or downright fake products need to be pulled from the shelves. Most of my observations were over a period of 60+ days (remember two different units), so it's highly unlikely I can get my money back.
J. Robinson
J. Robinson@username
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I really like the idea of smart home products. Unfortunately I've had so many issues connecting this thermostat to my Wi-Fi that I've been forced to use it as a dumb device. Let me start off by saying that I've worked in IT for about 10 years and by day-to-day job is designing, configuring and installing wireless networks. So I feel like I have a little knowledge in this area. I currently have a couple of TP-Link smart plugs and an Orbit smart sprinkler system controller which all connected to my wireless network without issue. This thermostat is an exception to this and I have wasted several hours and contacted Emerson support multiple times in an attempt to get it to connect. When I was finally able to get the thermostat to connect to my network it was more by luck than anything else. I didn't do anything differently compared to my several dozen other attempts. It just happened to work that time. Things were great for about 2 weeks until the battery indicator went from showing fully charged one morning to almost dead by the afternoon and the Wi-Fi had disconnected. After replacing the batteries I'm now back to my original problem of attempting to get the device to connect to my network. At this point I'm not sure if I have the heart to spend hours trying to get it to reconnect. Based on the many positive reviews for this device I'm left to wonder if I have a defective unit or if there's something specifically about my network that it doesn't like. As a dumb thermostat it works fine and the $75 rebate from my local utility company meant I got a pretty good price, but I can't recommend this device to friends or family. If for no other reason than I'd be the one they call for help if they can't get it to connect.