NEST Your Old Thermostat : 4 Steps (with Pictures)
Honeywell Thermostat has always been my favorite for years, not just because of its long 100 years of history but for the range of thermostats it has given in these years.
This should be a great backup for any unexpected events.
While a thermostat doesn't have a set lifespan, on average, you can expect them to last at least 10 years.
The reasoning is that it takes more energy to heat up a cold house or cool down a hot house than it takes to maintain a steady temperature.