Trane XL850, Controller, TCONT850AC52UA, Z-Wave Certified, ZC08-14090003

I have the Trane XL 20i high efficiency system which I am very happy with. My old thermostat was the 950 and I began to have problems with it staying connected to the internet. I decided on this model since it has essentially the same functionality and was cheaper, just a bit smaller. I have been super pleased so far, it has worked flawlessly and has not disconnected one time. When we bought our home, it had this system already and truth be old, I could not afford to replace it with today’s equivalent but I love the Trane and it is very efficient. Good job on the 850!

The thermostat I got is an engineering sample that has crippled firmware that is unable to update or do any home automation or connect to the internet the to update software. It's totally useless. If you get one with firmware version 1.0.03E it's garbage! current version is 5.2, the listing states "version 4.55", which is acceptable but the unit I got was not even close. Furthermore, when I finally got Trane customer service on the phone, they told me the serial number is not one that is in their database, was not intended for sale, and is ineligible for any support, and a "Licensed Trane Professional" wouldn't work on it.I do have to say that the vendor upon hearing from me months later after purchasing the unit (it took me that long to figure out what the problem was since Trane doesn't exactly make it easy to get any kind of support without paying a "Licensed Trane Professional" for a house call....don't get me started on gratuitous occupational licensing...) refunded the purchase price very quickly.Just in case you're looking at installing one of these for your home automation - here's some information you might find useful...not for this particular listing but for the XL850 in general as well as the XL950 and XL1050 as they will have the same limitation. Although it IS Z wave compatible it CANNOT be added as a device to a Z wave hub. It IS a very limited Z wave hub that forces you to sign up for Nexia, a cloud-based automation provider. The thermostat monitoring is free, but if you want to use it for other things, that'll cost you.There are some rudimentary Smartthings scripts that can basically log into your Nexia account and control some basic functionality, it is not 100% compatible or easy to set up.I decided to rip out my Comfortlink II controller and put in "normal" thermostat wiring so I can install a real z wave thermostat that doesn't force you change your home automation system, script your own work-arounds, and deal with proprietary closed-system support models.

I had an original XL 950 which started acting up. It is no longer available, but XL1050 is now the latest.I found that the features of the XL850 was all that I needed (remote access to my thermostat) and was quite a bit more affordable

We were told we had to have one of these XL850 units to control our new variable speed Trane heat pumps. It worked well for the first month but within a couple of days of connecting it to wifi it started rebooting, first slowly then constantly to the point where it was off most of the day. There is no way to reset this device that I can find, no batteries to replace, etc. and disconnecting it from the wall didn't seem to power it off either so I'm guessing there are internal batteries somewhere. For us there isn't a clear circuit for this device in our home but I've tried resetting all of heat pump and furnace related breakers to no effect. Needless to say we were left in the cold and stuck heating our home with our fireplace. Fortunately we are still under warranty so will wait for our hvac company to come out and replace the unit.A second big issue for me is their usage of Z-wave. While the advertising is true, you can view and control the thermostat remotely, what they don't tell you until looking deep into the instructions is that this device wants to be your primary controller and nothing else. If you really want to control all of your smart devices (z-wave only) through your thermostat (which is honestly ridiculous) then maybe this makes sense but there are far more flexible and capable controllers out there (Hubitat for instance) that easily outperform this and would be altogether cheaper with a less expensive thermostat.Given the above issues I won't be setting up wifi again which negates most of the reason for getting this thermostat above much cheaper options. Stay away from this one if you can and shame on Trane for foisting their expensive thermostats on their customers to get features out of their furnace or heat pump.

Overall the thermostat works well, but the screen saver function cannot be disabled and has a maximum delay setting of 30 minutes. In screen saver mode only the temperature is displayed, white on a black screen, jumping its position around the screen every 5 seconds. This is extremely irritating as the motion repeatedly draws the eye and attention from whatever else you're doing. I like the default, classic screen and want it on continuously, but am stuck with the extremely poor choice made by the designers to force their misguided concept of a "screen saver" on everyone forced to use their product. This is not an old-fashioned CRT display subject to "burn-in". The screen saver is an antiquated concept that hasn't been a technical necessity for decades.