Emerson Sensi Reviews Thermostats

Emerson Sensi review: a great WiFi thermostat at an affordable price

Our Emerson Sensi WiFi thermostat rating:

Emerson Sensi at a Glance

Image of the Emerson Sensi thermostat hardware mounted on a wall. The screen is illuminated and displays the room's temperature, system status, fan status, and target temperature.
Pictured: The Emerson Sensi, a WiFi thermostat with all the features you want and a price point that will leave enough cash left over for some decent takeout.

The Emerson Sensi is our go-to smart thermostat recommendation for installations without a C-wire, shoppers on a budget, and anyone in need of a “simple” smart thermostat that still does virtually everything you might want it to.

Our hands-on experience with the Sensi was simple and straightforward: a family member had a winter cabin they wanted to monitor and adjust the temperature of remotely, the Sensi made it possible. That was back in 2016, and the Sensi’s been a “fire and forget” solution for that home.

Quick Look

Emerson Sensi


  • System alerts, humidity control, fan control, +/-1 degree swing range
  • No C-wire required for many systems (see exceptions)
  • Control from anywhere in the world via the app
  • Same size and shape as a "normal" thermostat
  • Easy installation, easy to use app
  • Works with Amazon Alexa, Google Assistant, Apple HomeKit, Samsung SmartThings


  • Not a humidistat replacement - you've been warned
  • Can't schedule just the fan by itself
  • Requires cloud access for control via app, no intranet control

It just works

Here’s our Sensi, installed in 2016:

Emerson Sensi smart thermostat mounted on a wall
Note: Our installation site did not allow for hiding the wires in the wall, but most homes allow for hiding wires in the wall behind the unit.

The on-unit controls are fairly limited. You can raise/lower the temp, turn the fan on/off (if there is one), and tweak the schedule, but for nearly all of these things it’s easier to do them through the app or through a linked assistant. We link our thermostats to the Google Home app and control them there, but we found the Sensi app intuitive and easy to use.

Sensi HVAC Compatibility

No C-wire is required if your system is:

  • Conventional heating and cooling, such as a gas furnace, air conditioner, electric furnace, or boiler

You will need a C-wire if your system is:

  • Heat-only gas furnace, electric furnace, or boiler
  • Cooling-only (just an air conditioner)
  • Heat pump

Sensi’s own website offers a handy compatibility checking tool.

Like most (if not all) smart thermostats, the Sensi is not compatible with line voltage and proprietary systems, gravity furnaces, in-floor, or millivolt wall systems.

Sensi Favorite Features

There’s a lot to love about the Sensi, but here’s some of our favorite features. For a longer list of features, check out Sensi’s own website.

Different schedules for different days. Generally, we like being able to set different schedules for each day of the week, since our work from home days and children’s schedules vary.

Early start feature starts heating or cooling “ahead of time” so the house is at the desired temp by the time you want it to be that temp.

Price point. For the way we use a thermostat, the hardware mounted to the wall doesn’t matter that much. We do all of our control through the app or the Google Home app. For that reason, we liked saving $100 (or more) versus buying a pricier smart thermostat. With flagship thermostats like the Nest and Ecobee, a lot of what you’re buying is the fancy touch screen, and in our case we didn’t mind not paying for a touch screen we didn’t need.

Sensi Drawbacks

You can’t schedule the fan independently. Say you want the fan to come on when you go to bed and stay on until you get up – Sensi didn’t make this available in the app. At least, they didn’t at the time of this writing (2021). It’s always possible they’ll add it.

It’s not a stylish thermostat. That’s fine with us, but don’t buy this for your spouse who asked for a Nest for Christmas. It’s got a plasticky feel to it and the buttons have that 1990s feel to them. That said, you may not want a futuristic-looking thermostat on your wall. (This one really comes down to personal taste.)

Swing range too tight for some users. Swing range preferences vary by user – some people want the house held at 72 degrees no matter what, even if it means the heating comes on/off more frequently. Some people don’t care if the house drops to 69 before the heat kicks back on and they don’t want the heating coming on/off so often. This is purely a personal preference thing, but the important thing to know here is that the Sensi lets you adjust what they call the “cycle rate”.

Not a panacea for all systems lacking a C-wire. As much as we wish a WiFi thermostat could run entirely on two AA batteries, the Sensi cannot. No WiFi thermostat can. If you have no C-wire, the Sensi will only work for you if you have both heating and cooling. If you only have heating or cooling, you will need to run a C-wire or consider something like the Venstar Add-a-Wire.

No “local” (intranet) control. This isn’t unique to the Sensi, but if you were hoping for a smart thermostat you could use without going through someone’s cloud server, the Sensi isn’t it. (At the time of this writing, all of the major smart thermostats are like this.)

Great app, easy to use

Scheduling, overrides, and settings are right there on the smartphone app, which is nice looking and easy to figure out. The app is available for iOS (reviews and screenshots) and Android (reviews and screenshots). The worst complaint about the app seems to be the occasional inability to connect.

Emerson Sensi app screenshots
Set and edit schedules from your smartphone or tablet.

Installation and setup

You’ll need to make an account with Sensi (through the app) when you set up your new Sensi thermostat and register your device. Be sure to write down the access code found on the back of your Sensi before you mount it to the wall, because you’ll need it during setup (if you forget, though, no big deal – it’s also included on a sheet of paper in the box).

On my first setup attempt I accidentally neglected to finish registering the Sensi thermostat – and that prevented it from fully integrating itself with my app. So that’s my one bit of advice for setup: be sure to complete the registration step, or else you’ll be wondering why your thermostat doesn’t show in the app.

Once you’ve got the setup complete, your Sensi app will change to reflect the current mode and temperature.

(I’ve edited the name and location out of these screenshots because this is one of my own, not manufacturer’s screenshots.) 

The upper right corner of the app’s default screen shows today’s high and low temperature, as well as current temperature and location.

From here, you can set up schedules and adjust the current target temperature via the “hotdog” (or “hamburger”) menu in the upper left corner. A tray pops out to show schedule options, settings, account info, access to help, and more.

Overall, we found the app straightforward to navigate and use.

In the box

  • Sensi Wi-Fi thermostat
  • Thermostat base
  • Quick start guide
  • Mounting screws
  • Wire labels
  • Security code card for hooking up with the web portal and app
  • 2 AA batteries

The bottom line

The Sensi is a great thermostat well worth it’s low price tag.

We love the low cost, ease of installation, and the way you don’t really sacrifice anything by going with this “budget” model. For us, it just worked – and that’s all we wanted. We installed ours in 2017 and five years later in 2021 it’s still going strong.

The short of it

Emerson Sensi

Powerful and budget-friendly

Easy to install, easy to use, with all the features you'd want in an app-controlled WiFi thermostat. A rich feature set, good HVAC compatibility, and a low price point make this one a winner.

Note to readers: Some links on are affiliate links. Read our full disclosure policy here.

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Emerson Sensi WiFi Thermostat
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34 replies on “Emerson Sensi review: a great WiFi thermostat at an affordable price”

I believe the Pro version is cheaper because you have to have it installed by a HVAC certified company in order to benefit from the 5 years warranty. The DIY version has the consumer grade regular 3 years. You can still buy the Pro version but if you need to use the warranty within the 5 years, you will have to call a company to have it switched and honor the warranty which can cost you more at the end.

I intend to purchase the Emerson Sensi to help manage peak demand using a veryspecific schedule and like that there are up to 10 daily schedules so I can coordinate it with a second AC unit thermostat. Can it be scheduled to set a temp at any time (not just 15 minute intervals) meaning… at 3:40pm and set to 72 and then at 4:25 set to 80? Thank you.

It was upgraded automatically and now has a lock feature (kids, businesses).
Also, I think it always worked with Wink home automation or it too was added.

Great product. I’ve had mine for almost a year. There is one huge missing feature, however, and it’s not usage reports. Many users that I know (I’ve had 4 friends install one) have complained about the inability to set their own custom swing. If the swing is 1 degree and the set temp is 70, the system will heat at 69 and turn off at 71. If the swing is 2 degrees and the set temp is 70, the system will heat at 68 and turn off at 72. This feature would allow more user control for better comfort and would also prevent short cycling, which can quickly damage equipment. Please give us this important feature! Thanks Team Sensi!

i believe you can essentially change the differentials by the “cycle setting” in the app. slow = longer cycles = longer “swing”.. —-> fast (the opposite)

I live in rural Wisconsin and don’t have cell coverage yet. I can set up the units at our vacation home on someone else’s smartphone not my clamshell burner, or a laptop. After that I can access the app with any browser based device and erase the app on the borrowed smartphone. Seems like a small improvement that would be easy to implement would be browser based setup.

We have two new furnaces with two central a/cs that two thermostats should manage well remotely. Can’t wait for them to arrive.

[…] If you don’t have a smart thermostat already and you’ve always had your heart set on a Nest, this is the best Nest yet – go for it. It’s definitely not worth switching over from our top pick, the Ecobee 3, and if all you really want is a WiFi thermostat (and don’t mind plopping down less than half as much cash), check out the Emerson Sensi. […]

A quick note – this unit supports only US and Canadian time zones. I’ve got mine installed on the east coast of Australia, and it’s a bit painful using Hawaiian time (20 hours behind) to schedule! Emerson support have committed to consider other time zones, but I’m not holding my breath.

Also, the Honeywell units permit 0.5 degree Celsius control, the Emerson only 1 degree. It’s minor, but a degree Fahrenheit is about twice as precise as a degree Celsius and you lose that precision using the unit with metric units.

Yes, I have the same problem. I just installed one in Melbourne, Australia and works fine and the only problem is it does not support our time zone…Hope the new firmware comes soon!

We are away from home for thee months during the winter. How low can the heat mode be programed for an extended time period.

That depends on the type of heating system. For gas fired forced hot air system by Lennox they recommend not going below 55degrees or else condensation will corrode the heating chamber. The thermostat can be set below that. I haven’t tried below 50 degrees.

Is this unit compatible with a WINDOWS SMARTPHONE?
I dislike APPLE products as they they are WAY overpriced, and Android is too “ICONY” for my tastes and a bit confusing for an “OLD DOS” nerd like me.

I have two concerns regarding this Sensi Thermostat:
– It can ONLY be programmed or change programs via its
app or online access. The natural place to program is at the
thermostat per se and not via the internet. No internet
connection means you’re SOL in changing one’s program
– The internet connection to Sensi is iffy and comes an goes
– Customer service is not much help and troubles were out of box
I recommend wifi thermostats like Lennox’s (I enjoy 1 at my cabin)

The box says it does not require a “C” wire on “most” systems. My 2009 Furnace is not most systems I guess.

Saying your product is “Universal” when it is does not work even just on the systems on Earth is deceptive advertising intended to trick consumers into buying a product that costs thousands of dollars to install.

I am returning mine to Home Depot.

I originally gave these thermostats a 5 rating, but each time you change cell phone or router you face a new ordeal. I replaced my router and cell and got support to remove them from registration and since then ZERO connectivity. They have become expensive “normal” thermostats that i could have got for $8 at home depot. THINK TWICE!

Cannot be set below 50F. To access from web browser you need to subscribe to sensi manager service for $10/year/thermostat. sensi manager service would not accept my CC information. I will be buying something else, this thermostat is far too limited to be of any value.

Not worth the aggravation. First, the one I purchased was defective. Had to run back to Home Depot at 9pm after spending a few hours working in the heat (no thermostat=no cooling) and with tech support to make it work only to find out the unit was defective. Then the second took a while to get set up – HVAC wiring from previous thermostat was not compatible with this device – although the app said it would work fine!

Then, after getting it all set up and running I start having issues with wifi. Inconsistent – sometimes online sometimes offline. Turns out now Sensi support is saying that wifi won’t work consistently without a C Wire. DO NOT BUY THIS PRODUCT IF YOU HAVE A HEAT ONLY, COOL ONLY OR HEAT PUMP WITHOUT A C WIRE!

Note that most of the online documentation leads you to believe that this device works without a C Wire on “Most” units. “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. and Canada. A c-wire is required for heat-only, cool-only and heat pump (without aux) systems and for use with Apple HomeKit. ”

If you look at the compatibility chart, you will see a long list of incompatibility without a C wire.

However, support will not tell you that until you’ve spent countless hours reconfiguring and even though they knew I had a heat pump. Their options now are run a c wire or buy a kit that replaces it. BTW – Search for No C Wire on their support site and you get no results. Support site is awful!

No I have to go back to Home Depot and return the thing. No box or packaging as I threw that all away once the unit was working to provide adequate cooling.

I’ve spent more time on trying to make this thing work that it’s worth. Should have stayed with a traditional programmable…And not Emerson!

I’ve had mine for about a year, running on batteries and connected to my wifi. Never had to change the batteries yet. Seems your review is very off on this point.

I spent a day installing the wifi w/up/down button (avoid touch screen issues) nd the o/b wire problem, HP1/HP2 selections, and other install related issues the average installer will run into is not in the manual. After getting it all to work on my own using a little trial and error, needed to connect to wifi, and of course the instructions don’t help. After emailing tech support and not getting replies I called. The girl walked me through a few steps and I was connected to the app via wifi. Why is that not in the manual? I started to wonder how to use Alexa with it and before I did I tried to go through the steps to get my wife’s iPhone connected and poof! No wifi connection. Took out batteries, nothing. Waited and hour, nothing. I believe the only way is to reboot your router. At this point I’m thinking, what if I lose power briefly like it does sometimes? I really don’t want to go through all of this. I bought an Alexa dot and it doesn’t need reconnecting after a power loss, nor does many other smart home items, but this new wifi thermostat needs special care every time. No thank you. Bought on Amazon but through a seller. Won’t take it back, wants me to contact the manufacturer. There’s a lot wrong here.

You might be suffering from the Wifi. 2G or 5 G issue . My provider cut my 2G as it was causing problems in my house . So now the Sensi is non Wifi connectable Which is ironic given that was the major reason to purchase .

Great thermostat although the one I have is defective. the correct wire combination does not work and after emailing them 3 times and waiting on the telephone 3hours with no help or answer. I had to figure a go around to make it work. Everything works when it should not. I had to wire the cool section to run the furnace; figure that out. But it works. I am still trying to get a answer from Emerson.

We have the Sensi thermostat the fan is running all the time there are two choices auto and on which ever you choose the fan is running non stop is there a way to turn fan of for a bit.any help would be appreciated we are seniors and not too savvy re wifi ..any help will be appreciated.

I have had my Sensi for three years. My only complaint is battery life. I have to change them every two months. Then the hassle begins reprogramming.

I have a Sensi thermostat ,I’m happy with all functions , except I need to replace batteries often , tried different brands and the longest it lasted is less then 3 months
Is this normal? Or is wired wrong ?

The comment about requiring a C-wire is 100% false. The Emerson ST55 absolutely works on Wi-Fi without a C-wire for my oil-burning, heat-only boiler system. The two AA batteries are still at full capacity four months after installation. I wish people would actually try using a device in all applications before making false assumptions based on the manufacturer’s specs.

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