I just purchased two Nest Learning thermostats. After installing the first one, I spent an hour or so trying to understand the learning features, especially as Early On and how the thermostat can start the furnace earlier or later, depending upon the outside temperature data it receives from the web.
What disappointed me is that this feature only works if someone is not only home, but detected by the system as being home. This is stupid! What I want is for the thermostat to turn on the heat so that it is at the desired temperature when we arrive. What is the point of having the ability to calculate the preheat time, if you have to walk into a cold house when you arrive? Stupid.
So I will have to do what I have always done, which is to guess how long it will take to heat up, depending on my experience, maybe adjusted as the winter goes along. This will either waste energy by starting too soon on a mild day, or fail to have the room comfortable when I arrive. Either way, this is a failure to take advantage of all the technology in these devices.
I won't return the Nest devices, because (SFAIK) they are the only Wi-Fi thermostats that do not need a "C" wire and that I can use with our old, simple 2-wire furnace wiring. And I can still start the furnace remotely, so that is an advantage.
But the term "Learning Thermostat" simply does not apply, I guess, unless there are always people at home (and detected).
