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"

First, make sure that the thermostat has the shrink wrap on the box and nothing has been opened or damaged. (This happened with the first thermostat that was shipped to me. I returned it and, when the credit was issued as a gift card balance, I reordered the thermostat.) Shipment was very quick in both cases. Also, order the backplate for this thermostat if you want to hide any holes from the previous thermostat.Once you create the Sensi account, you can install the thermostat using the Sensi app. The thermostat was fairly easy to install. Follow along with the Sensi app, and in no time you will have successfully installed the thermostat.I had an older Emerson thermostat (since taken over by Sensi), so I am pretty familiar with the interface and app. The Sensi app is much more polished and easier to use than the Resideo app that is used with Honeywell Home thermostats. The Sensi app responds much more quickly than the Resideo app.The Sensi app also has humidity settings. In high humidity, the thermostat will overcool up to 3 degrees below the set temperature to remove excess humidity. (The Resideo app doesn't do that!)The Sensi app gives you the option to lock the thermostat display, which will allow you to control the HVAC only through the app.

I worked in HVAC for some years prior to entering the new field and have installed my fair share of thermostats. Recently purchased a house and it came with an Ecobee 4. Had nothing but issues with it. Would crash randomly and take up to 25 minutes to reboot, and in general does not carry ease of use.Now onto the Sensi touch. Amazingly simple to install and wire, the app even gives you a guide so you can designate what your previous wiring was at the terminals of the thermostat and it will automatically reconfigure and give you a 2-D diagram of positive wire up the Sensi using your existing wiring. Once wired up, I finished registering in the app and was able to control my thermostat remotely on my phone. Both of the app and the thermostat itself are quality, sleek, simple and is incredibly easy to use. I know there are a lot of high tech options out there, but if you are looking for something that is easy to install, reliable, and really offers most of what you would get when spending several hundred dollars on a thermostat for a flat $100. I highly recommend it.

Yes, I give it 5 stars. I love the thing. It was easy to set up, and I've had no issues at all with the software. I love finding my bedroom getting too hot at 1 AM and being able to simply roll over and reset the temp with my phone. Also, as I have an exotic bird, I don't use the geo fencing, as it needs to stay warm enough for her, or cool enough. But, I can see the temp when away from home and adjust it, if necessary. So, why the BUT....?Well, before you buy it, you should understand that this needs a 'C' wire to function on ANY level. Many similar thermostats that require a 'C' wire, also accept batteries. With batteries installed in them, they can control the system, like any normal thermostat. All that they are missing without the 'C' wire, is the wireless functions. But, this Sensi model doesn't accept batteries, at least I sure couldn't find any place for them. Also, in a response to a customer's question, the seller mentioned that this model requires the 'C' wire for ALL functions. In spite of this, if you look above, at the product specs, it states that it requires 2 'AA' batteries! But, the thing is a sealed assembly with no place to install any batteries.So, if you buy this and think you'll go ahead and install it and use it without wireless until you can solve the 'C' wire problem, DON"T! Have everything ready, including either a 'C' wire (which in some cases can be added, running directly from your HVAC unit to the Sensi thermostat), or a supplemental transformer to replace the 'C' wire, BEFORE you remove your old thermostat. I saw this battery issue when I received my Sensi, so I ordered a supplemental transformer from Amazon, that was to arrive the next day by 9:00 PM. The next afternoon, expecting to have the transformer by 9, I installed the thermostat. The carrier that was to deliver the transformer lost it! I got an email at around 4 PM telling me so. So, in order to be able to have AC in my bedroom that night, I had to drive to Home Depot and buy one, and it cost me $4 more than the Amazon unit, which I returned to Amazon. But, they paid the shipping for me.So, if your system doesn't have the 'C' wire, learn what it is going to take for you to add it with a supplemental transformer. Be sure you're up to the job (it really is easy), and order both the Sensi, and the supplemental transformer, together. Don't let the 'C' wire intimidate you. It's not that hard to install the supplemental transformer, and you can make it look better if you use surface mounted wire races (available on Amazon) between the thermostat and the supplemental transformer, to hide its wires.The supplemental transformer has 2 wires, but it's AC (alternating current), so it isn't necessary to observe polarity. You simply hook one wire to the same terminal as the red 'R' wire in the thermostat, and the other wire connects to the thermostat's terminal labeled, 'C'. Simple! Also, you do have the option of using any 24 VAC transformer with a MINIMUM of 300 milliamps of current available at its output. Transformers sold for this purpose have exactly that voltage and current. But, it's acceptable to go higher in current output. Doing so simply gives you headroom, and lets the transformer run cooler. But, NEVER go LOWER than 300 ma. Voltage is another matter. You can go up, but only about a volt, or 2, which is what I did, as all I could find was a power adaptor for a Rain Bird sprinkler system that was 25.5 volts AC at 750 milliamps & cut the plug off the end of the wires, so I could hook them to my Sensi. So, if you can use a screw driver & some wire cutters, or sharp scissors, buy one and enjoy!!