Edwin Pawlowski wrote:
"Robert11" wrote in message
What happens if the battery runs down while you are away ?
I know, use new, fresh, batteries, etc. But- A bit worried about this.


Replace the batteries once a year. I've had programmable state for about 20
years and never had a problem from battery failure.

Some of the digital models have a failsafe mechanical backup that will
kick in at a fixed low temp like 45. You'd have to pull up the specs
to see if this one has it.

For digital thermostats, I like the Honeywell LCD touchscreen. Not
sure of the model, 8600?. Two key features I like are adaptive
recovery, where you just set it for the time you want the new temp to
be reached, eg 70 at 7AM. Based on experience, the thermostat gets
the furnace going at whatever time prior to 7am that it figures out it
needs to. It also has vacation hold mode, where you can set a temp to
be held for X days before it resumes it's regular schedule.