EMERSON Sensi Touch Wi-Fi Smart Thermostat with Touchscreen Color Display, Works with Alexa, Energy Star Certified, C-wire Required, ST75W , White

Initial Impression is Very Good
——————————-Update October 2020:——————————–Working flawlessly since install. I never notice any issues with it’s ability to keep the temperature where I want it.———————————Original Review: Aug 2020:——————————–This is a replacement for a Bryant/Carrier T6-NHP 2 wire thermostat used on a carrier Air Handler and a Bryant condenser unit. My problem was that the air conditioner would never stop once it started. I decided that this job is a “Do It Yourself” job due to the pandemic and since I am a retired Electrical Engineer, debugged it on my own.Not knowing much about HVAC, to get started, I had to dig into how it all works. After quite a bit of learning and diagnosing, I finally determined that the old thermostat was malfunctioning. Probably a sticky relay.The first thermostat I tried was the Honeywell RTH7600D which has a dated appearance, and had limited options for different kinds of systems. It would not work with my 2 stage heat pump. Oddly, there was no option to invert the O signal in heat pump mode. Returned.The Sensi cost more but looked more promising. It arrived with virtually no instructions. The idea is you look at web videos and go through the setup screens.Prior to installing, I like to bug out the signals to make sure they work as expected.Two problems here:1) The Sensi needs 24 VAC to work. No sign of a battery. So I ordered a 24VAC power supply.2) The wires are connected to a well designed terminal block on the back plate. No screwdriver needed here, just push to connect, just like a stereo speaker. This block is labeled however, for bench testing, when you snap the thermostat to the back plate to get power, you can access the wires only via probe points. The problem is they are not labeled. I added my own labels here and was able to bug out the unit. Note, there are two methods to bug out the thermostat.1) look for 24VAC on the various pins, while connected to the C wire with the other probe.2) Look for continuity between the Red wire RC or RH and the various output. I found out that the first method is problematic as the unit presents 24VAC to the output when it is active or not. They apparently did not install a pull down resistor on these outputs, and they float high. I consider this a design defect simply due to the confusion it could cause. I suspect it results in a number of returned units, however it is not a functional issue.When I re separated the thermostat from the back plate after debugging, I was surprised to see the LEDs still powered on in the thermostat. Apparently, there is a super-cap or maybe a non-customer battery in there somewhere to keep the unit up through small power glitches.I wired up the unit. and continued the install. Connecting to WIFI was seamless. All it asked for was to identify which network (SSID) to connect to, and the password. Nothing else.The phone app works well also. No connectivity glitches so far.The Sensi does not support the Dehumidify signal on my air handler, but it takes care of dehumidify in a similar way itself. You have good control over that also.The user can also switch on predictive programming, which causes the Sensi to arrive at your desired temperature at the specified time.You can set multiple daily schedules in the app. All pretty straight forward. It appears that you can set as many as 8 set points per day as desired. Unfortunately, the user interface is a bit rough around the edges. Once I created a specific schedule, I could not find a way to delete it. So, just be sure to modify the provided schedule for your first schedule. You can also set the unit to go fan only periodically to avoid stale air in the duct work. The unit knows outside temperature but that is through the web. It does not support the outside temperature sensors provided by my system. I would like to see the unit display the weather on the thermostat, but alas no, but is is on the phone app. It is not clear how much functionality is lost if internet connectivity is lost, but I would recommend a different thermostat if you do not have wireless internet. A nice feature is the web display can show you how many hours the system runs in each mode per day. It does not break down high cool/low cool in 2 stage heat pumps however. I would like to see that feature.There is a modest amount of control over the algorithm, but information provided about exactly what and how the unit does what is does is not to be found. Fortunately, it seems to do its job of regulating temperature in an efficient way pretty well. It is an attractive unit, but be aware that the screen starts to fade out at a 45 degree angle. I will update after I get some more experience, however so far so good.Note: Unit needs to have an internet connection for all but basic functionality.Problem: If unit goes dead, It may not be the unit. Check to make sure you still have 24VAC available. Many HVAC units shut off the 24VAC when the drain overflow switch gets triggered, such as during a drain clog.By the way, Amazon recommended to get a “Emerson F61-2663 Wall Plate for Sensi Wi-Fi Programmable Thermostat”, along with this purchase. This is not needed, it is a mistake. Don’t order it.

I like the ability to use my phone to access remotely. Very simple to install. The app install tutorial provided step by step instructions which were very easy to understand. Nice screen making the current temp easy to read.

I needed a thermostat that would work with a two-stage furnace and A/C system. What I like about this one is the nice clear uncluttered display with good size fonts. I also like that it offers an offset option in case the temperature is not being read correctly. Mine agreed with another thermometer out of the box so I didn’t need to apply an offset. The app is fairly easy to use, and setting up the schedule was quick and easy. I don’t use Alexa so can’t comment on that integration.A few initial annoyances, though:1. The installation demands that you install an app and register the product, including providing your phone number. There is no conceivable reason why the company genuinely needs my phone number and I resent the fact that it’s a mandatory field in the setup.2. The first step in the installation process is to say which product you have, choosing from a provided list. None of the options in the list exactly matched the name or appearance of this product and the list does not include product numbers, so it took a little guesswork.3. The initial setup seemed to be more complex than necessary, requiring the user to connect to the thermostat wi-fi system, then to the home system, then to the thermostat system again.4. The terms and conditions are long. The main thing I got out of skimming them was a strong emphasis on the fact that there is no warranty on the software. It makes me wonder what has gone wrong with their software on other installations that makes this such an important point for the company. It seems to me that if you’re selling a product that includes both hardware and software, you should take responsibility (and provide a warranty) for both.

Tape on box!Opened found back plate had paint on it and sub base all full of greasy debris!!Not happy one bitUSED!!!!