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!

We bought this to replace a 1050. Trane/American Standard only sells the 1050 through installers and we were looking at over $1500 for diagnostics and equipment. We ended up purchasing the 850 through another storefront. The AC system worked fine but the thermostat was horribly off. We did adjust the calibration but given this issue, the poor quality of the 1050, the horrible ratings found elsewhere, and the cost, we returned the 850 and will seek another solution. Note, there is an option to have the screen saver go black.

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.

No issues. The indoor temperature sensor can easily be calibrated. I had read the install and setup instructions before I puchased so I knew I would be able to calibrate the temperature sensor once it was installed. After I installed the new tstat I used a Fluke temp meter to monitor the temp at the tstat for a couple of days and compared that to the temp showing on the tstat. The tstat temperature was consistently off by +2 degrees so I used the temp calibration function on the tstat to program the offset and haven’t looked back. The tstat temp now tracks with the temp on my Fluke. I didn’t experience any issues setting up the tstat and connecting to the internet. I bought the tstat from the local Trane distributor so I didn’t have to worry about shady resellers. 100% happy with the Comfortlink ll XL850.

This thermostat (or XL1050) is _required_ if you are using a communicating-only outdoor unit, like the XV19. I'm going to rip out my $50k system to get rid of this damn thermostat. It's completely unacceptable. As well, the communication bit feels useless. Perhaps the load on the outdoor unit is fully variable, but I can't tell because the hybrid furnace (also communicating, required to use the XV19, 650 speeds) only comes on at 1 speed with this thermostat - high. No matter the temp differential. The biggest beef I have with it is that the thermostat refuses to maintain a calibration, and it is insanely slow to update. After starting off at stable temperature, calibrating using a fluke meter, then running the air at "high" for awhile (not intentinoal! that's the only speed it runs at), the house gets down to low 60s and the thermostat still reads 72. There is a significant temperature differential if I take a drwall surface temp just below and just above the thermostat. This self-heating must have something to do with the inability to hold a calibration. It's reading its own electronics waste heat. Plus all the other poor aspects of this thermostat. It really is that bad. Stay away from Trane.