A:Answer Yes, it's easy to install and set up on the phones or tablets so no need to spend $99 for installation fee. The important tricks are (1) make sure you turn the power off at indoor unit (machine) because even though the small wires won't electrocute you but it can burn the little fuse inside the indoor unit (machine). If the fuse burns the nest thermostat won't have current to run and it won't be easy to search and replace the fuse inside the big machine. (2) make sure you take the pictures of the wires connecting to the old unit because you just have to reconnect them to the same initials, like Green wire to G in old thermostat and Green wire to G in new thermostat (Nest) too. (3) another important trick is make sure those wires are not too bulky, otherwise the unit won't attach well to its base. You may have to cut some to shorten or push deeper inside the hole on the wall (where wires came out from) to keep the minimum wire bulk so it won't be pushing out the thermostat.
I actually replaced my old (still working) 4 thermostats at home with all new Nest 3rd generation learning thermostats. One of them I didn't switch off the power, then I felt a little bit of current like from a small battery on the tip of my finger, then I realized that the fuse was gone.
I also noted the thermostats were not attached well to the bases but eventually figured out the bulky wires. Once I cut the long wires and made them perfectly short, the thermostat mounted to its base perfectly.
One last thing is that all these Nest thermostats can be easily detached so can be stolen easily, no professional burglar skills required!
