I have your garden variety thermostat, the basic model from Home Depot or Lowe’s — it’s pretty much the same one everyone has. It’s my third one, they all work the same way. The same wrong way.
It divides the week into days, and the days into 4 timezones. You then program any of these time-sections to a certain temperature, and voila, it takes care of it. Why they even come with suggestions, for instance you can easily select either Winter or Summer for their pre-defined programs.
And if you want to go manual? Even better, you just push the up or down button until you hit the right temperature and walk away. Sounds pretty good, no?
You walk away and everything is fine, until you hit the next time-section. Then it goes back to the programmed temperature. In effect, it overrides your override. Suppose I go on vacation for 5 days. Or I’m sick and need a little more heat than usual. There’s no way to simply tell it, “stay at 72,” because a couple hours later it will decide that 68 would really be better all things considered.
This is my third thermostat as a homeowner, and all three have had this “feature”. The weird part is that it can’t take any more effort to make it work the right way. How hard it is to build a manual override that actually, you know, overrides the other programming?