This was quite reasonably priced, had an instruction manual that seemed to accomodate almost any system configuration one might find, and had a set of labels included so as to be able to map and follow the wires. I had bought this for the simplest of systems, a ceiling mounted propane heater, so installation was straight forward. The programming was simplicity. So why did I remove one star?

One feature that would have been easy to include in the firmware would have been an automatic reset to the program temp settings after either a prescribed time period, or at the next wake-leave-return-sleep event. As it is, if one manually overrides the temperature command, that override stays in place until one manually removes it. At least, that's the best I can get out of it. With the heater in my shop, it means if I forget to reset it when I leave, it wastes heat.

Works great

For a gas only system with only two wires, this is so easy to install and use. I am red/green color blind. Just hook up the white wire to W terminal, and the dark wire to the RH terminal. On the dry wall, mark and drill two holes using an 11/16" drill bit for the screws' drywall anchors. Tap in and secure. The display light defaults to a dim mode (saves batteries), but snaps to highly visible blue contrast by tapping top menu button. Programmable 4 levels (M-F, and Sa, and Su), say 1. warm at 6 am, 2. cooler at 9 am (no one home); 3. warmer at 4 pm ; cold at 11 pm. You can adjust the thermometer to +- 3* F by accessing the 'Technician' setup mode.

I used this to replace a 2-wire connection between my furnace and my ancient thermostat. It works well so far.

our old thermostat wasn't the efficient, this one saving us at least $200 every month in winter time. bought two to replace on both floor.