- Energy Star rated
- CSA or CMHC approved
- 5/2 or 7 day programming
- Humidifier interface -humidistat
- Furnace filter change reminder (keep your heating/cooling system operating at peak performance)
- Low battery indicator
Other things to consider that are more convenient than a necessity are: back-lit displays (great for night-time), daylight saving time clock feature, touchscreen displays (these are kind of cool looking) and of course look for a warranty.
Make sure that the unit you purchase is compatible with your type of heating system, and if you have an air conditioner, look for a unit that will control that as well.