I wasn't sure where this went so feel free to move and reprimand me! ;-) I have the Apple-endorsed Nest thermostat and it stopped working last night. I called their support and the guy had a real time view of all my connected wires. It was really cool. He had me move a wire and I got my heat back. He told me I must have had a terminal go bad. He offered to send me a brand new unit under warranty so I figured why not. So, I'm getting a 2nd get Nest! I can't praise their support enough. All companies should be like that.