Honeywell TH8110R1008 Vision Pro8000 Thermostat

Installed as a replacement thermostat for a conventional AC and forced-air gas heat system that had a thermostat mounted in the "wrong" room. This unit, combined with two of the C7189R1004 Wireless Indoor Sensors, let me move the temperature measurement point away from the thermostat to the places in our multi-room zone where two of us work all day. You can optionally enable or disable the thermometer inside the thermostat itself so that you're only reliant on (an average of) the remote wireless sensors. This is exactly the change we wanted and the result is a very comfortable, rock-solid steady temperature in our part of the zone all day long. Plus it gives us a lot of features we didn't have before, such as treating our large home office like a commercial building. So it will run a fan continuously during our "open hours" while the AC cycles on no more than 3 times per hour. We can start an air purge an hour before work begins. All of this is easily configurable in the Installer Options menu. None of this was really clear to me when reading the description with all the "if / but" caveats and compatibility warnings. I was able to install this thermostat pretty easily by doing a wire color map-over from the 5 wires going to my old tstat (red goes to R, white to W, etc with the only tricky one being blue/common goes to C). The whole thing works like a charm. At first, it was misbehaving and the fan would not turn on. I uninstalled and reinstalled the thermostat and then it worked perfectly. Apparently, I had a loose wire the first time, an easy mistake to make with the wire-block terminal it employs. Be careful that you really do have solid continuity in the connections, otherwise, you could end up with weird behavior like I saw at first. Speaking of which, my system shows 24 volts AC between the red wire and any other. Test yours with a voltmeter if you want to know that you'll have the same great plug-and-play experience that I had. If you have a heat pump or other system, this thing might even be smart enough to make that plug and play but I can't speak to that. By the way, the instructions are garbage and the phone support unreachable (seriously I got a "we're busy, call back in the future" recording). If this didn't end up working for me after the reinstall, I would have sought help from an hvac pro online or in my town. Or I might just send this unit back and buy one with understandable instructions. For example, the installation guide says that you must have the Redlink unit to work with the Wireless something. So did that apply to me and the sensors that I bought? No. It was talking about some other features that I didn't want or buy. Like we're supposed to know all this Honeywell terminology as an end user. Just plug it in, see if it works, and stuff the return to the seller if it doesn't. Maybe they'll get the message and make setup less confusing for an end user.