On the other hand, my simple Honeywell thermostats do wonderfully because I can program them to my actual schedule and only need to adjust things twice a year. Sure, it's probably not as efficient as a dynamic algorithm, but I'd rather to do this than worry about waking up freezing in the middle of the night, or worse, having my condenser unit fried by an over-eager thermostat by starting/stopping it constantly.
I am thinking of getting something Wi-Fi compatible though because setting the temp from my phone would be really nice. Too bad not many work with multi-zone systems.
That's my big problem with Nest. A basic programmable thermostat with manual override and a delayed blower feature is probably an 85% solution. Machine learning on top of that, for a single-family residence, is ridiculous overkill for very little gain.
The heat was set to go back to the daytime temperatures at 6 AM, and I began to wake up at about 5:47 every morning when, like clockwork, the furnace kicked on to reach 64 degrees before I rolled out of bed. Well played, Honeywell engineers.
Honeywell has been in business for 110 years. If you are in business that long you gotta be doing something right! I would assume.
When I was in grad school, I wired a temperature controller to an experiment, set it, satisfied myself that it was working OK, and went away. Guess what. The relay failed, and the heater was stuck on, until it melted the experiment.
As a grad student in physics (not even EE or embedded systems), I could chalk it up to a beginner mistake.
But if you design a commercial product that controls the release of large amounts of energy, you can't make beginner mistakes. There many not be many remaining reasons why age and experience are valuable traits in a engineer, but this is one of them. Germane to one of the other comments, this may also be why a 110 year old company still has a reason to exist.
The honeywell is simple, but works well. Has a vacation mode, and tells my kids how warm or cold it is outside.. cool!
When I was ready to switch to a programmable thermostat to save money, I really, really wanted to like the Nest. It was cool, whizzbang, etc., etc. But then I started reading the 1-star reviews on Amazon, and the support forums. And it worried me. People came home to apartments that were 90* because their heaters were stuck on full blast during the summer. All sorts of people bought $300 Nests, only to discover their 8-year-old equipment was apparently not compatible with it. People spoke of Nests being fried by voltage surges in "old" (a scant 4 years!) HVAC systems. EEs were comparing the Nest's voltage regulators to that of a generic $20 thermostat and finding the generic more reliable in every aspect.
Nervous that my 14-year-old system would annihilate a very expensive toy, and that my wife staying at home would make the thing pointless, regardless, I bought a $100 Wifi Honeywell with a traditional 7-day calendar. It's fantastic. I expected very little from Honeywell, who I regard as a quaint, old-skool company, but their Android and web apps are simply excellent. Easy to use, well-designed, and it just works. I saved about $120 in utility bills in the first 8 months I had it, living in the nebulous division of the continental climate and humid subtropical climate in the midwest.
When we moved to San Diego to a house with only central heat, no AC, I still dropped $70 on the same thermostat just to have access to the "what temperature is it in my house right now" feature.