Comment Re:millions of devices (Score 1) 182
I've seen a lot of thermostats that change their clock settings twice a year with no way to make that not happen.
My thermostat doesn't have any notion of DST, so it's wrong for about two months per year because it takes about a month for me to notice that the furnace is running extra early or extra late and that I need to change the time on the thermostat by and hour by choosing the "Set Clock" option.
But thermostats are cheap and simple to replace, so if I actually cared I could replace it and so could anybody who has one of the weird ones you've seen.
Mine doesn't know what DST is because it has no idea what date it is, it just repeats a seven day cycle endlessly. I'm not sure what excuse there is for designing a thermostat that actually knows the date but doesn't have an option for changing or disabling DST. A thermostat like that would be incompatible with parts of the US and all of Europe and Asia. Why would someone design a thermostat that's hard coded to only work in a specific geographic area and only as long as DST practices never change. It's not like the anti-DST discussion is new. It's been going on for decades.